JP4410551B2 - Method for estimating temperature of fuel injection valve, and method for correcting fuel injection amount using fuel temperature estimation method - Google Patents

Description

  The present invention relates to a method for estimating the temperature of a fuel injection valve and a method for correcting the injection amount of a fuel injection valve using the temperature estimation method.

Generally, in an internal combustion engine, the fuel injection amount is regulated by controlling the valve opening time of a fuel injection valve connected to the fuel pipe.
FIG. 11 illustrates the cross-sectional structure of the tip portion of such a fuel injection valve. As shown in FIG. 11, a space is formed in the main body 20a of the fuel injection valve, and this space is filled with fuel. A fuel injection hole 20c is formed at the tip of the main body 20a. The opening on the inner space side of the main body 20a in the injection hole 20c forms a valve seat portion 20d, and the tip portion of the needle valve 20b, which is a valve body, comes into contact with the valve seat portion 20d. The injection hole 20c is closed and the fuel injection valve is closed (a state indicated by a two-dot chain line in FIG. 11). On the other hand, when the needle valve 20b is lifted by driving of an actuator or the like (state shown by a solid line in FIG. 11), that is, when it is opened, the tip of the needle valve 20b is separated from the valve seat 20d and the injection hole 20c. Is opened, and the fuel injection valve is opened. And the fuel in the main body 20a is injected from the injection hole 20c through the clearance CL which arises between the front-end | tip part of the needle valve 20b, and the valve seat part 20d.

  By the way, in the fuel injection valve, even if the valve opening time is the same, if the temperature is different, the fuel injection amount also becomes different. Such a change in the temperature characteristic of the fuel injection valve lowers the control accuracy of the fuel injection amount. It becomes a factor to make. Examples of factors that change the temperature characteristics of the fuel injection valve include the following.

  First, since the needle valve 20b and the main body 20a expand under a high temperature atmosphere and contract under a low temperature atmosphere, the gap CL changes depending on the temperature of the needle valve 20b and the main body 20a. Accordingly, even if the control amount of the fuel injection valve is the same, if the temperature is different, the amount of fuel passing through the gap CL will be different, and the temperature characteristic of the fuel injection valve will be changed.

Further, when the temperature of the injected fuel changes depending on the temperature of the fuel injection valve, the fuel density and the like change, so that the temperature characteristic of the fuel injection valve also changes.
Thus, the temperature characteristic of the fuel injection valve that affects the injection amount is related to the temperature of the fuel injection valve. Therefore, if the temperature can be grasped, the degree of change can be estimated.

Various devices for grasping the temperature of such a fuel injection valve have been proposed.
For example, in the thing of patent document 1, the temperature of a fuel injection valve is detected using a temperature sensor.

  Moreover, in the thing of patent document 2, the temperature (tip temperature) of a fuel injection valve is estimated by multiplying an intake air temperature, a cooling water temperature, etc. by a predetermined coefficient. More specifically, the estimated temperature of the fuel injection valve is calculated using the following calculation formula.

Estimated temperature of fuel injector = (a × THW + b × THA) / (a + b)
THW: Cooling water temperature
THA: Intake air temperature
a, b: coefficients for weighting (set appropriately according to the type of internal combustion engine)

Japanese Patent Laid-Open No. 2-5723 JP-A-7-12031

  By the way, as described in Patent Document 1, when the temperature of a fuel injection valve is actually detected using a temperature sensor, the cost of parts of the sensor, the number of manufacturing steps required for installation, and the like increase.

  On the other hand, according to the calculation formula described in Patent Document 2, the temperature of the fuel injection valve can be estimated to some extent without using a temperature sensor. However, since the calculation formula simply models the actual heat transfer in the fuel injector, its estimation accuracy is naturally limited, and it is possible to meet the demand for more accurate estimation values. It is impossible.

  Incidentally, in the device described in Patent Document 2, the temperature of an intake system fuel injection valve that injects fuel into the intake passage is estimated, but the fuel injection valve directly enters the combustion chamber of the internal combustion engine. There are also fuel injection valves for in-cylinder injection for supplying fuel. This fuel injection valve for in-cylinder injection has its tip portion exposed to combustion gas and its mounting position close to the combustion chamber, etc., compared with the fuel injection valve for intake system. Temperature and the like tend to be higher. For this reason, when estimating the temperature of the fuel injection valve for in-cylinder injection, a large deviation is likely to occur between the estimated temperature and the actual temperature even if the above-described simple heat transfer model equation is used. The inventor has confirmed.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a temperature estimation method for a fuel injection valve that can estimate the temperature of the fuel injection valve with higher accuracy. It is another object of the present invention to provide a fuel injection valve injection amount correction method capable of suppressing a decrease in control accuracy of the fuel injection amount due to the influence of temperature characteristics of the fuel injection valve.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 estimates the temperature of the fuel flowing into the fuel injection valve based on the flow rate of the fuel flowing from the fuel pipe into the fuel injection valve connected thereto and the temperature of the fuel pipe. Based on this, the gist is to estimate the temperature of the fuel injection valve.
The invention according to claim 2 estimates the temperature of the fuel flowing into the fuel injection valve based on the flow rate of the fuel flowing into the fuel injection valve connected to the fuel pipe from the fuel pipe, and based on the estimated temperature The gist is to estimate the temperature of the injection valve.

  First, the temperature of the fuel injection valve can be estimated based on the temperature of the fuel flowing into the fuel injection valve. Here, the temperature of the fuel flowing into the fuel injection valve, in other words, the fuel flowing through the fuel pipe, tends to decrease as it goes from the fuel injection valve to the fuel tank. Accordingly, when the flow rate of the fuel flowing through the fuel pipe increases, more fuel having a relatively low temperature flows into the fuel injection valve. Therefore, the fuel flowing into the fuel injection valve based on the flow rate of the fuel is increased. Can be accurately estimated. Therefore, according to the above method, heat transfer of the fuel flowing into the fuel injection valve can be accurately modeled, and the temperature of the fuel injection valve can be accurately estimated. Incidentally, since the flow rate of the fuel in the fuel pipe increases as the fuel injection amount increases, the flow rate can be calculated based on the fuel injection amount.

Further, in the first and second aspects of the present invention, in the temperature estimation method for the fuel injection valve, the fuel distribution pipe to which the fuel injection valve is attached has a branch portion where the fuel is diverted, and is more than the branch portion. The gist of the estimation of the temperature of the fuel flowing into the fuel injection valve on the downstream side is to correct the flow rate of the fuel on the basis of the distribution ratio of the amount of fuel diverted at the branch portion.
As described above, the temperature of the fuel flowing into the fuel injection valve tends to decrease as the fuel flow rate in the fuel pipe increases. Here, the fuel corresponding to the distribution ratio of the fuel amount in the diversion portion is introduced into the fuel injection valve provided on the downstream side of the branch portion. Therefore, when estimating the temperature of the fuel flowing into the fuel injection valve on the downstream side of the branch portion of the fuel distribution pipe, the above method in which the flow rate of the fuel is corrected based on the distribution ratio of the fuel amount to be branched at the branch portion. According to this, the temperature of the fuel flowing into the fuel injection valve provided on the downstream side of the branch portion can be accurately estimated.
Here, in the case where the fuel distribution pipe is branched into a fuel pipe having a small change degree in the flow direction of the fuel and a fuel pipe having a large change degree in comparison with the fuel distribution pipe, As the flow rate of the fuel increases, more fuel flows into the fuel pipe with a smaller degree of change in the fuel flow direction. Therefore, according to the third aspect of the present invention, the distribution ratio can be set based on the flow rate of the fuel. In this case, the distribution ratio is set in a manner in which distribution ratios corresponding to various fuel flow rates are set in advance or a distribution ratio is calculated using an approximate expression using the fuel flow rate as a parameter. Can be set.
Here, the temperature of the fuel pipe can be estimated by multiplying a predetermined coefficient by the ambient temperature of the fuel pipe, that is, the temperature of the air around the fuel pipe. Since heat is exchanged between the fuel pipe whose temperature can be estimated in this way and the fuel flowing through the fuel pipe, the temperature inside the fuel pipe is determined based on the ambient temperature of the fuel pipe and the flow rate of the fuel. The fuel temperature can be estimated with higher accuracy. Therefore, according to the invention described in claim 4 , by adopting a method of estimating the temperature of the fuel injection valve based on the ambient temperature of the fuel pipe in accordance with the flow rate of the fuel, the fuel injection valve The temperature can be estimated with higher accuracy.

As the atmospheric temperature of the fuel pipe, in addition to the temperature of the air, a method of estimating the atmospheric temperature of the fuel pipe based on the intake air temperature as in the invention according to claim 5 can be adopted. .

According to a sixth aspect of the present invention, in the temperature estimation method for a fuel injection valve according to any one of the first to fifth aspects, the temperature of the main body in which the injection hole of the fuel injection valve is formed is determined. The temperature is estimated based on the temperature and the temperature of the portion where the fuel injection valve is attached, and the temperature of the valve body that opens and closes the injection hole is estimated separately from the main body based on the estimated temperature of the fuel. This is the gist.

Since the valve body of the fuel injection valve is surrounded by fuel, the temperature of the valve body can be estimated based on the temperature of the fuel flowing into the fuel injection valve. Here, as described above, according to the temperature estimation method for a fuel injection valve according to any one of claims 1 to 5 , the temperature of the fuel flowing into the fuel injection valve can be accurately estimated. According to this, the temperature of the valve body can be accurately estimated.

  On the other hand, in the main body of the fuel injection valve, heat is exchanged between the fuel inside the fuel injection valve and the portion to which the fuel injection valve is attached. Here, the temperature of the fuel in the fuel injection valve can be accurately estimated by the temperature estimation method as described above. Further, the temperature of the part to which the fuel injection valve is attached, for example, the temperature of the engine body can be estimated based on a predetermined parameter. Therefore, by using parameters such as the estimated fuel temperature and the temperature of the part where the fuel injection valve is attached, the heat transfer of the fuel injection valve body can be accurately modeled, and the temperature of the body can also be accurately estimated. Will be able to.

  Here, even when the fuel injection valve is opened, the gap generated between the valve body and the main body changes under the influence of temperature, and thus the temperature characteristics of the fuel injection valve change. Accordingly, the temperature of the main body and the temperature of the valve body can be accurately estimated. Therefore, the amount of thermal expansion / contraction of the main body and the valve body can be accurately estimated, and such a change in temperature characteristics can be properly grasped. Incidentally, the tip temperature of the fuel injection valve can also be estimated by correcting the estimated main body temperature based on a predetermined coefficient.

In addition, the temperature of the site | part to which the fuel injection valve was attached can be estimated based on cooling water temperature like the invention of Claim 7 .
According to the invention of claim 8 , by calculating a difference between the estimated temperature of the valve body and the temperature of the main body, a difference between the temperature of the valve body and the temperature of the main body is estimated. By adopting such a method, it is possible to estimate the temperature difference between the two where the influence of the estimation error or the like of the fuel temperature is eliminated as much as possible, and it is possible to suitably ensure the estimation accuracy. As a result, the change amount of the gap due to the thermal expansion / contraction of the main body and the valve body as described above can be grasped more suitably.

The invention according to claim 9 is applied to the temperature estimation method for the fuel injection valve according to any one of claims 1 to 8 . The fuel pipe is divided into a plurality of fuel temperature estimation areas from a portion where the atmosphere temperature of the fuel pipe can be the pipe temperature to the fuel injection valve, and is estimated in the upstream fuel temperature estimation area. The main point is to add the fuel temperature as a parameter used for estimating the fuel temperature in the downstream fuel temperature estimation region immediately after that.

  According to this method, a plurality of fuel temperature estimation regions are set from the upstream side to the downstream side of the fuel pipe, and the fuel temperature estimated in the upstream fuel temperature estimation region is in the immediately downstream downstream fuel temperature estimation region. This will be reflected in the estimation of the fuel temperature. Accordingly, it is possible to accurately estimate the fuel temperature in each region in correspondence with the temperature distribution in the entire length direction of the fuel pipe, and thus it is also possible to estimate the temperature of the fuel flowing into the fuel injection valve more accurately. Here, in the same configuration, a portion where the ambient temperature of the fuel pipe can be set to the pipe temperature is set in the most upstream fuel temperature estimation region. Therefore, the fuel temperature in this fuel temperature estimation region can be estimated easily and accurately, and consequently the fuel temperature in each downstream fuel temperature estimation region estimated sequentially can also be estimated with high accuracy. In addition, "the part which can make the atmospheric temperature of fuel piping the piping temperature" means the part where both temperature is substantially equal.

Thus, according to the method of any one of claims 1 to 9 , it is possible to accurately model the heat transfer of the fuel flowing into the fuel injection valve, and to accurately estimate the temperature of the fuel injection valve. Can do. Therefore, the injection such as by the method of claim 1 0, the fuel injection valve even if fuel injection supply cylinder injection fuel injection valve directly into a combustion chamber of an internal combustion engine, namely the fuel into the intake passage Even if the fuel injection valve for in-cylinder injection tends to have a higher temperature than the fuel injection valve for the intake system to be supplied, the temperature can be accurately estimated.

The invention described in claim 1 1, a injection amount correction method of the fuel injection valve, the temperature of the fuel injection valve estimated by the temperature estimation method of the fuel injection valve according to any one of claims 1 to 1 0 The main point is to correct the injection amount of the fuel injection valve in accordance with the engine load.

  According to this method, the injection amount of the fuel injection valve is corrected based on the temperature of the fuel injection valve accurately estimated by the temperature estimation method as described above. For this reason, it is possible to suppress a decrease in control accuracy of the fuel injection amount due to the influence of the temperature characteristic of the fuel injection valve.

In particular, in the fuel injection valve injection amount correction method to which the fuel injection valve temperature estimation method according to any one of claims 6 to 8 is applied, the fuel injection valve is open, Even if the gap generated between the fuel injection valve body changes due to the influence of the temperature, and the temperature characteristics of the fuel injection valve change accordingly, the fuel injection amount corresponding to the change can be corrected. It becomes like this.

(First embodiment)
Hereinafter, a fuel injection valve temperature estimation method according to the present invention and a fuel injection valve injection amount correction method using the temperature estimation method according to a first embodiment will be described with reference to FIGS. I will explain.

  FIG. 1 schematically shows fuel piping of a V-type six-cylinder internal combustion engine 10 to which a fuel injection device for an internal combustion engine according to this embodiment is applied, and a vehicle 1 on which the internal combustion engine 10 is mounted.

  As shown in FIG. 1, an internal combustion engine 10 is mounted in an engine room 2 formed in front of the vehicle 1. On the other hand, a fuel tank 54 is attached to the rear of the vehicle 1. In the fuel tank 54, a fuel pump 53 for feeding fuel is attached. The fuel pump 53 is connected to the high pressure pump 52 via a low pressure fuel pipe 49. The high pressure pump 52 is connected to the delivery pipe 51 via the high pressure fuel pipe 50. The delivery pipe 51 is a fuel distribution pipe, and a plurality of fuel injection valves 20 are provided.

FIG. 2 schematically shows the internal combustion engine 10 and its peripheral configuration.
As shown in FIG. 2, the internal combustion engine 10 includes a cylinder head 11 and a cylinder block 13 in which a plurality of cylinders 12 are formed. A piston 14 is provided in each cylinder 12 so as to be able to reciprocate. A combustion chamber 15 is formed by the piston 14 and the inner wall of the cylinder 12 and the cylinder head 11.

  In the cylinder head 11, a fuel injection valve 20 for in-cylinder injection that directly injects fuel into the combustion chamber 15 and a spark plug 22 that ignites the air-fuel mixture in the combustion chamber 15 are provided in each cylinder, that is, the first cylinder #. The first to sixth cylinders # 6 are provided respectively. Although FIG. 2 shows the configuration of the first cylinder # 1, the configurations of the other cylinders are the same. The fuel injection valve 20 has the same structure as the fuel injection valve shown in FIG.

  That is, as shown in FIG. 11, a space is formed in the main body 20a of the fuel injection valve, and this space is filled with fuel. The front end portion of the main body 20a is exposed to the combustion chamber 15, and a fuel injection hole 20c is formed at the front end portion. The opening on the inner space side of the main body 20a in the injection hole 20c forms a valve seat portion 20d, and the tip portion of the needle valve 20b, which is a valve body, comes into contact with the valve seat portion 20d. The injection hole 20c is closed and the fuel injection valve is closed (a state indicated by a two-dot chain line in FIG. 11). On the other hand, when the needle valve 20b is lifted by driving of the actuator (the state indicated by the solid line in FIG. 11), that is, when it is opened, the tip of the needle valve 20b is separated from the valve seat portion 20d, and the injection hole 20c The fuel injection valve is opened and the fuel injection valve is opened. And the fuel in the main body 20a is injected from the injection hole 20c through the clearance CL which arises between the front-end | tip part of the needle valve 20b, and the valve seat part 20d. Moreover, the valve opening time of the fuel injection valve 20 is adjusted by the drive control of the actuator by the control device 40 described later, and the fuel injection amount is thereby adjusted.

  As described above, the fuel injection valve 20 is connected to the delivery pipe 51 via the high-pressure fuel pipe 50, and fuel is supplied from the delivery pipe 51. The delivery pipe 51 is composed of two pipes arranged in parallel and one communication pipe that communicates each pipe, and the shape thereof is substantially U-shaped. The fuel injection valves 20 corresponding to the first cylinder # 1, the third cylinder # 3, and the fifth cylinder # 5 are connected to one pipe. Further, fuel injection valves 20 corresponding to the second cylinder # 2, the fourth cylinder # 4, and the sixth cylinder # 6 are connected to the other pipe. The delivery pipe 51 is connected to an engine-driven high-pressure pump 52 that is driven by the camshaft 17 of the internal combustion engine 10. The fuel in the fuel tank 54 is pumped to the high-pressure pump 52 by the electric fuel pump 53, further pressurized to a high pressure by the high-pressure pump 52, and then supplied to the delivery pipe 51. Fuel is injected from the fuel injection valve 20 at a pressure substantially equal to the fuel pressure in the delivery pipe 51. Further, the fuel pressure in the delivery pipe 51, that is, the fuel injection pressure of the fuel injection valve 20 is adjusted through the adjustment of the fuel pumping amount in the high-pressure pump 52. The delivery pipe 51 is connected to a return pipe 55 for returning the pumped fuel to the fuel tank 54. A relief valve 56 is provided in the middle of the return pipe 55. The relief valve 56 is opened when the fuel pressure in the delivery pipe 51 exceeds a predetermined pressure. As described above, in this embodiment, fuel is supplied from the fuel tank 54, the fuel pump 53, the low pressure fuel pipe 49, the high pressure pump 52, the high pressure fuel pipe 50, the delivery pipe 51, each fuel injection valve 20, the return pipe 55, the relief valve 56, and the like. The piping system is configured.

  The internal combustion engine 10 is provided with various sensors for detecting the engine operating state and the like. In the vicinity of the crankshaft, a crank angle sensor 30 for detecting the rotational speed of the crankshaft (engine rotational speed) and its rotational phase (crank angle) is provided. A cam angle sensor 31 that detects the rotational phase (cam angle) of the cam shaft 17 is provided in the vicinity of the cam shaft 17. Further, an accelerator sensor 32 for detecting the depression amount (accelerator opening) is provided in the vicinity of the accelerator pedal, and an intake air amount sensor 34 for detecting the intake air amount is provided in the intake passage 18.

  Further, the cylinder block 13 is provided with a water temperature sensor 33 that detects the temperature of the cooling water of the internal combustion engine 10 (engine cooling water temperature). Further, an oxygen sensor 35 that outputs a voltage signal corresponding to the oxygen concentration of the exhaust is attached to the exhaust passage 19.

  All the detection signals of these sensors 30 to 35 are taken into the control device 40 of the internal combustion engine 10. The control device 40 includes a memory for storing and holding various control programs, calculation maps, data calculated when the control is executed, and the like. The control device 40 drives the fuel injection valve 20, the ignition plug 22, the high-pressure pump 52, and the like based on detection signals from various sensors such as the sensors 30 to 35, so that the fuel injection control, the ignition timing, etc. Perform various engine controls.

  As described above, the tip of the fuel injection valve 20 in the present embodiment is exposed to the combustion chamber 15 and is directly exposed to the combustion gas in the combustion chamber 15. Further, compared to an intake system fuel injection valve for supplying fuel to the intake passage 18, the attachment position thereof is closer to the combustion chamber 15. The temperature of 20a tends to increase. For this reason, the gap CL shown in FIG. 11 changes depending on the temperature of the fuel injection valve 20, and even if the control amount of the fuel injection valve 20 (for example, valve opening time, actuator drive amount, etc.) is the same, the temperature can be different. The fuel injection amount will be different. In particular, when the engine load is high, the intake air amount and the fuel injection amount are increased and the temperature in the combustion chamber 15 rises, so that the temperature of the main body 20a tends to be further increased. On the other hand, since more fuel flows into the fuel injection valve 20 when the engine load is high, the temperature increase of the needle valve 20b surrounded by the fuel is higher than the temperature increase of the main body 20a. The temperature rise is reduced. Therefore, the difference between the temperature of the main body 20a and the temperature of the needle valve 20b is increased, and the gap CL is also increased. Therefore, even when the valve opening time of the fuel injection valve is the same, the fuel injection amount is larger when the engine load is high than when the load is low.

  Such a change in the temperature characteristic of the fuel injection valve causes a decrease in the control accuracy of the fuel injection amount. However, since the temperature characteristic is related to the temperature of the needle valve 20b and the main body 20a, the temperature is grasped. If possible, the degree of change can be estimated. Incidentally, since the needle valve 20b is in the fuel injection valve 20 and surrounded by the fuel, the temperature of the fuel in the fuel injection valve 20 and the temperature of the needle valve 20b substantially coincide. Therefore, in the present embodiment, the temperature (main body temperature) Ti of the main body 20a of the fuel injection valve 20 and the fuel temperature Tf in the fuel injection valve 20 that substantially matches the temperature of the needle valve 20b are accurately estimated as follows. Like to do.

First, the temperature estimation method of the fuel injection valve in this embodiment, specifically, the estimation method of the main body temperature Ti and the fuel temperature Tf will be described with reference to FIGS.
In this embodiment, when estimating the fuel temperature Tf, as shown in FIG. 3, the fuel pipe is divided into a plurality of regions (in this embodiment, five regions) continuous in the fuel flow direction, and the fuel temperature is estimated for each region. Like to do. Specifically, fuel temperature estimation regions such as region A, region B, region C, region D, and region E are set sequentially from the upstream side in the fuel flow direction. Regions B to E are regions in the fuel piping in the engine room 2, and in particular, region E is set as a region corresponding to the fuel injection valve 20. Accordingly, the fuel in the region E flows into the fuel injection valve 20, and the fuel temperature TfE in the region E becomes the fuel temperature Tf in the fuel injection valve 20 described above. On the other hand, the region A is set as a region in the fuel pipe outside the engine room 2. Accordingly, the temperature of the fuel pipe in the region A can be the ambient temperature in the region A, that is, the temperature of the air around the fuel pipe, and the ambient temperature of the fuel pipe in the region A and the pipe temperature are substantially equal. Yes.

  On the other hand, FIG. 4 schematically shows a heat transfer mode in the main body 20 a of the fuel injection valve 20. In the present embodiment, the fuel injection valve 20 is attached to the cylinder head 11. Therefore, when modeling heat transfer, the cylinder head 11 and the main body 20a around the main body 20a are made into one member and are modeled collectively.

  As shown in FIG. 4, heat transfer occurs from the cooling water to the main body 20a and the cylinder head 11 (this heat transfer amount is assumed to be ΔQ1 [J / s]). Further, heat transfer occurs from the main body 20a and the cylinder head 11 to the fuel flowing into the fuel injection valve 20 (this heat transfer amount is assumed to be ΔQ2 [J / s]). Further, heat transfer occurs from the main body 20a and the cylinder head 11 to the atmosphere of the main body 20a (this heat transfer amount is assumed to be ΔQ3 [J / s]). Therefore, the heat transfer in the main body 20a can be expressed by the model equation shown in the following [Equation 1].

なお、各熱伝達量ΔＱ１、ΔＱ２、ΔＱ３は次の［数２］〜［数４］にてそれぞれ表すことができる。

The heat transfer amounts ΔQ1, ΔQ2, and ΔQ3 can be expressed by the following [Equation 2] to [Equation 4], respectively.

ここで、本体雰囲気温度Ｔｉｒｏｕｎｄと前回推定された燃料噴射弁の本体温度Ｔｉｏｌｄとはほぼ等しいと考えることができるため、上記熱伝達量ΔＱ３は「ΔＱ３＝０」になる。

Here, it can be considered that the main body atmosphere temperature Tround and the previously estimated main body temperature Tiold of the fuel injection valve are substantially equal, so the heat transfer amount ΔQ3 is “ΔQ3 = 0”.

  Then, while substituting [Equation 2] and [Equation 3] into the above [Equation 1], the matching coefficients K1 and K2 are changed to “K1 = (hi1 · Si1) / (Mi · Ci)”, “K2 = (hi2). If defined as “Si2) / (Mi · Ci)”, [Equation 1] becomes the following [Equation 5].

この［数５］を用いて燃料噴射弁２０の本体温度Ｔｉを推定することができる。すなわち燃料噴射弁２０内の燃料の温度に相当する領域Ｅの燃料温度ＴｆＥと、燃料噴射弁２０が取り付けられた部位の温度を推定することのできる冷却水温ＴＨＷとをパラメータとして燃料噴射弁２０の本体温度Ｔｉは推定することができる。なお、領域Ｅの燃料温度の推定については後述する。

The main body temperature Ti of the fuel injection valve 20 can be estimated using this [Equation 5]. That is, the fuel temperature TfE in the region E corresponding to the temperature of the fuel in the fuel injector 20 and the cooling water temperature THW that can estimate the temperature of the portion where the fuel injector 20 is attached are used as parameters. The body temperature Ti can be estimated. The estimation of the fuel temperature in the region E will be described later.

  On the other hand, FIG. 5 schematically shows a heat transfer mode in the fuel in the fuel pipe. 5 conceptualizes the heat transfer in each of the regions B to E, and the region X indicates any one of the regions B to E (X = B, C, D, E).

  As shown in FIG. 5, heat transfer occurs from the air around the fuel pipe to the fuel pipe (this heat transfer amount is assumed to be ΔQ5 [J / s]). Further, heat transfer occurs from the fuel pipe to the fuel in the pipe (this heat transfer amount is assumed to be ΔQ4 [J / s]). Further, the temperature of the fuel flowing through the fuel pipe tends to become lower as it goes from the fuel injection valve 20 to the fuel tank 54. Therefore, when the flow rate of the fuel flowing through the fuel pipe increases, more fuel having a relatively low temperature flows into the fuel injection valve 20, and the temperature of the fuel flowing into the fuel injection valve 20, that is, the above-mentioned The fuel temperature Tf tends to be low. As described above, the temperature change of the fuel flowing into the fuel injection valve 20 can be accurately estimated based on the flow rate of the fuel, and the heat transfer in the fuel in the fuel pipe is represented by the following model equation [6] Can be expressed as The heat transfer in the fuel pipe can be expressed by the following model equation [Equation 7].

  Incidentally, in this embodiment, it is assumed that the piping temperature and the fuel temperature are approximately equal in each region.

なお、燃料噴射量Ｑが増大すると燃料配管内の燃料の流量は増大する。すなわち燃料流量と燃料噴射量Ｑとは相関関係にあるため、本実施形態では燃料の流量を示すパラメータとして、機関負荷と機関回転速度等から算出される燃料噴射量Ｑを利用するようにしているが、もちろん、燃料噴射量Ｑに代えて燃料の流量そのものを用いるようにしてもよい。

When the fuel injection amount Q increases, the fuel flow rate in the fuel pipe increases. That is, since the fuel flow rate and the fuel injection amount Q are correlated, in this embodiment, the fuel injection amount Q calculated from the engine load, the engine speed, and the like is used as a parameter indicating the fuel flow rate. Of course, the fuel flow rate itself may be used instead of the fuel injection amount Q.

また、各熱伝達量ΔＱ４ｘ、ΔＱ５ｘは次の［数８］、［数９］にてそれぞれ表すことができる。

Further, the heat transfer amounts ΔQ4x and ΔQ5x can be expressed by the following [Equation 8] and [Equation 9], respectively.

なお、配管雰囲気温度Ｔｐｒｏｕｎｄは次の［数１０］にて推定することができる。

The pipe atmosphere temperature Tround can be estimated by the following [Equation 10].

そして、上記［数６］及び［数７］に示した各式の両辺を加算した式に、［数８］及び［数９］を代入するとともに、適合係数Ｋ３、Ｋ４を、「Ｋ３＝（ｈｄｘ・Ｓｄｘ）／（Ｍｄ・Ｃｄ＋Ｍｆ・Ｃｆ）」、「Ｋ４＝Ｃｆ／（Ｍｄ・Ｃｄ＋Ｍｆ・Ｃ）」と定義すると次の［数１１］が得られる。そしてこの［数１１］で示される式を用いて各領域における燃料温度Ｔｆｘを推定することができる。すなわち吸気温ＴＨＡと燃料噴射量Ｑとをパラメータとして各領域における燃料温度Ｔｆｘは推定することができる。

Then, [Equation 8] and [Equation 9] are substituted into the equation obtained by adding both sides of the equations shown in [Equation 6] and [Equation 7], and the matching coefficients K3 and K4 are expressed as “K3 = ( When defined as “hdx · Sdx) / (Md · Cd + Mf · Cf)” and “K4 = Cf / (Md · Cd + Mf · C)”, the following [Equation 11] is obtained. The fuel temperature Tfx in each region can be estimated using the equation shown in [Equation 11]. That is, the fuel temperature Tfx in each region can be estimated using the intake air temperature THA and the fuel injection amount Q as parameters.

そして、各領域Ｂ〜Ｅの燃料温度は［数１１］で示される式に基づき、次の［数１２］に示される各式によって推定することができる。

And the fuel temperature of each area | region B-E can be estimated by each formula shown by following [Formula 12] based on the formula shown by [Formula 11].

また、本実施形態において、各領域毎では配管温度と燃料温度とがほぼ等しいものと仮定している。そして、領域Ａの燃料配管の温度は、領域Ａの雰囲気温度と略等しくなっているため、領域Ａの燃料温度ＴｆＡは上記［数１０］で示される式を領域Ａについて適用した次の［数１３］で示される式に基づき推定することができる。

In the present embodiment, it is assumed that the piping temperature and the fuel temperature are substantially equal for each region. Since the temperature of the fuel pipe in the region A is substantially equal to the ambient temperature in the region A, the fuel temperature TfA in the region A is obtained by applying the equation shown in [Expression 10] above to the region A 13] can be estimated.

このように本実施形態では、燃料配管の上流側から下流側にかけて連続した複数の燃料温度推定領域が設定されており、上記［数１１］に示されるように、上流側の燃料温度推定領域において推定された燃料温度がその直後の下流側の燃料温度推定領域における燃料温度の推定に順次反映されていく。従って、燃料配管の全長方向における温度分布に対応させて各領域の燃料温度を精度よく推定することができ、ひいては燃料噴射弁内に流入する燃料温度もより精度よく推定することができる。また、燃料配管の雰囲気温度と同燃料配管の温度とが略等しい部位を最も上流側の燃料温度推定領域、すなわち領域Ａに設定するようにしている。そのため、この燃料温度推定領域の燃料温度は容易に、かつ精度よく推定することができ、ひいては順次推定される下流側の各燃料温度推定領域における燃料温度も精度よく推定することができる。

As described above, in the present embodiment, a plurality of continuous fuel temperature estimation regions are set from the upstream side to the downstream side of the fuel pipe, and as shown in the above [Equation 11], in the upstream fuel temperature estimation region, The estimated fuel temperature is sequentially reflected in the estimation of the fuel temperature in the downstream fuel temperature estimation region immediately after that. Accordingly, it is possible to accurately estimate the fuel temperature in each region in correspondence with the temperature distribution in the entire length direction of the fuel pipe, and thus it is possible to estimate the temperature of the fuel flowing into the fuel injection valve more accurately. Further, a portion where the atmospheric temperature of the fuel pipe and the temperature of the fuel pipe are substantially equal is set to the most upstream fuel temperature estimation region, that is, the region A. Therefore, the fuel temperature in this fuel temperature estimation region can be estimated easily and accurately, and consequently the fuel temperature in each downstream fuel temperature estimation region estimated sequentially can also be estimated with high accuracy.

On the other hand, the main body temperature Ti estimated from the equation shown in the above [Equation 5] and the fuel temperature Tfx estimated from the equation shown in the above [Equation 11] are the current temperatures in consideration of the temperatures estimated last time. Although the estimation is performed, an estimated value immediately before the engine start can be set as an initial value for the previously estimated temperature. The estimated value at the time of starting the engine can be estimated as follows.
[Fuel temperature in each region immediately before engine start]
First, immediately before the engine start, it can be assumed that “current fuel temperature Tfx in region X = previous fuel temperature Tfxold in region X”. Further, since fuel injection is not performed, “fuel injection amount Q = 0”. Therefore, “Tfx = Tfxold” and “Q = 0” are substituted into the equation shown in the above [Equation 11], and the body temperature Ti immediately before the engine start is substituted into “Tiold” as the body temperature Tistart at the time of start. Is obtained, the following equation is obtained.

そして、［数１４］にて示される式において、機関始動直前の各領域Ｘの燃料温度Ｔｆｘを始動時燃料温度Ｔｆｘｓｔａｒｔとすると、各領域Ａ〜Ｅの始動時燃料温度Ｔｆｘｓｔａｒｔは次の［数１５］に示す各式から推定することができる。

In the equation shown in [Equation 14], if the fuel temperature Tfx in each region X immediately before the engine start is defined as the starting fuel temperature Tfxstart, the starting fuel temperature Tfxstart in each region A to E is expressed by the following [Equation 15]. It can be estimated from each equation shown in FIG.

［機関始動直前における始動時本体温度］
まず、機関始動直前では、「現在の本体温度Ｔｉ＝前回の本体温度Ｔｉｏｌｄ」であると仮定することができる。また、上記［数５］に示される式における「ＴｆＥｏｌｄ」は上記「ＴｆＥｓｔａｒｔ」に等しい。従って、［数５］に示した式に対して「Ｔｉ＝Ｔｉｓｔａｒｔ」、「Ｔｉｏｌｄ＝Ｔｉｓｔａｒｔ」を代入するとともに、「ＴｆＥｏｌｄ」には上述した領域Ｅの始動時燃料温度ＴｆＥｓｔａｒｔの算出式を代入する。そして、こうした各値や式が代入された［数５］の式を、機関始動直前における始動時本体温度Ｔｉｓｔａｒｔについて解くと次の［数１６］で示される式が得られる。

[Starting body temperature just before engine start]
First, immediately before starting the engine, it can be assumed that “current body temperature Ti = previous body temperature Tiold”. Further, “TfEold” in the equation shown in [Expression 5] is equal to the above “TfEstart”. Therefore, “Ti = Tistart” and “Tiold = Tistart” are substituted into the equation shown in [Equation 5], and the above-described calculation formula for the starting fuel temperature TfEstart in the region E is substituted for “TfEold”. . Then, when the equation [Equation 5] into which these values and equations are substituted is solved for the starting body temperature Tistart immediately before the engine is started, the following equation [Equation 16] is obtained.

そして、この［数１６］に示される式に基づいて始動時本体温度Ｔｉｓｔａｒｔは推定することができる。

The starting body temperature Tistart can be estimated based on the equation shown in [Equation 16].

  Here, with respect to the compliance coefficients KA, KB, KC, KD, and KE, a compliance test is performed so that the main body temperature Ti and the fuel temperature Tfx approach the actual temperature, and the respective values are actually calculated based on the results. Although it may be adapted, the degree of influence of heat reception from the body temperature Ti on the piping atmosphere temperature Tround tends to increase as the region A moves toward the region E. For this reason, the fitness coefficients KA to KE are successively increased with a tendency of “fit factor KA <fit factor KB <fit factor KC <fit factor KD <fit factor KE”. Accordingly, the adaptation coefficient KA and the adaptation coefficient KE are actually adapted based on the result of the adaptation test, while the other adaptation coefficients KB, KC, and KD are calculated based on the adaptation coefficient KA and the adaptation coefficient KE. It may be.

  In addition, with regard to the compliance coefficients K1, K2, K3, and K4, a conformance test or the like is performed so that the main body temperature Ti or the fuel temperature Tfx approaches the actual temperature, and the respective values are actually adapted based on the results. However, the present inventor has confirmed that in the fuel piping system according to the present embodiment, the fitness coefficients K1 to K4 can be approximated as points on a cubic curve. Therefore, you may make it calculate each adaptation coefficient K1-K4 with an approximate expression.

Next, fuel injection amount control in the present embodiment will be described.
[Control of fuel injection amount]
FIG. 6 shows a procedure for calculating the fuel injection amount executed by the control device 40.

  When this process is started, first, parameters related to the equations shown in the above [Equation 11] and [Equation 13] are read, and based on the equations shown in the [Equation 11] and [Equation 13]. The fuel temperature Tfx in each region A to E is estimated. Then, the fuel temperature TfE in the region E is estimated and calculated as the fuel temperature Tf in the fuel injection valve 20, that is, the needle valve temperature Tn that is the temperature of the needle valve 20b (step S110).

Next, parameters related to the equation shown in the above [Equation 5] are read, and the main body temperature Ti of the fuel injection valve 20 is estimated based on the equation shown in the [Equation 5] (step S120).
Next, a difference ΔT between the main body temperature Ti and the needle valve temperature Tn is calculated, and a temperature correction coefficient KT is calculated based on the difference ΔT (step S130).

  The temperature correction coefficient KT is calculated as the following coefficient. That is, when the fuel injection valve 20 is opened, the clearance CL between the needle valve 20b and the valve seat portion 20d of the main body 20a changes under the influence of temperature, and this changes the temperature characteristics of the fuel injection valve. Is also a correction coefficient that is set in order to correct the fuel injection amount corresponding to the change.

  The reason why the temperature correction coefficient KT is calculated based on the temperature difference ΔT is as follows. In other words, when the intake air temperature THA includes a detection error, the estimation accuracy of the fuel temperature Tf is slightly lowered, and the estimation accuracy of the main body temperature Ti may be in accordance with this reduction. Here, when the difference between the fuel temperature Tf (= needle valve temperature Tn) and the main body temperature Ti is obtained, the temperature difference between the needle valve 20b and the main body 20a in which the influence of such detection errors and estimation errors is suppressed as much as possible is obtained. Can be estimated. That is, even if the estimation accuracy of the temperature of the needle valve 20b and the main body 20a slightly decreases, the temperature difference between the two can be estimated with high accuracy. As a result, the change amount of the gap CL due to the thermal expansion / contraction of the main body 20a and the needle valve 20b as described above can be grasped more accurately.

  Next, the final fuel injection amount Q is calculated based on the equation shown in the following [Equation 17] (step S140), and this process is temporarily terminated.

このように、本実施形態では、燃料噴射弁の温度特性の変化を考慮して燃料噴射量が算出されるため、燃料噴射弁の温度特性の影響による燃料噴射量の制御精度の低下が抑制される。

As described above, in this embodiment, since the fuel injection amount is calculated in consideration of the change in the temperature characteristic of the fuel injection valve, a decrease in the control accuracy of the fuel injection amount due to the influence of the temperature characteristic of the fuel injection valve is suppressed. The

As described above, according to the present embodiment, the following effects can be obtained.
(1) The temperature of the fuel injection valve is estimated based on the flow rate of the fuel flowing into the fuel injection valve. Therefore, it is possible to accurately model the heat transfer of the fuel flowing into the fuel injection valve, and to accurately estimate the temperature of the fuel injection valve.

  (2) The temperature of the fuel flowing into the fuel injection valve, that is, the fuel temperature in the fuel pipe is estimated using parameters such as the ambient temperature of the fuel pipe and the flow rate of the fuel. Therefore, the fuel temperature in the fuel pipe can be estimated with higher accuracy, and as a result, the temperature of the fuel injection valve can be estimated with higher accuracy.

  (3) When estimating the temperature of the fuel injection valve, the temperature of the main body of the fuel injection valve and the needle valve are particularly estimated. Since the needle valve of the fuel injection valve, that is, the valve body is surrounded by fuel, the temperature of the needle valve should be estimated based on the temperature of the fuel flowing into the fuel injection valve, that is, the temperature of the fuel in the fuel injection valve. Can do. Here, in the said embodiment, since the temperature of the fuel which flows into a fuel injection valve can be estimated accurately, the temperature of a needle valve can be estimated accurately.

  On the other hand, in the main body of the fuel injection valve, heat is transferred between the internal fuel and the portion where the fuel injection valve is attached. Here, in the above embodiment, the temperature of the fuel flowing into the fuel injection valve can be accurately estimated as described above. Further, the temperature of the part to which the fuel injection valve is attached, for example, the temperature of the engine body can be estimated based on a predetermined parameter. Therefore, according to the above embodiment in which the temperature of the main body is estimated using parameters such as the estimated fuel temperature and the temperature of the portion where the fuel injection valve is attached, the heat transfer of the main body can be accurately modeled, The temperature of the main body can be estimated accurately.

  Here, even when the fuel injection valve is open, the gap generated between the needle valve and the injection hole of the main body changes under the influence of temperature, and even when the temperature characteristic of the fuel injection valve changes, According to the embodiment, it is possible to accurately estimate the temperature of the main body and the temperature of the needle valve. Therefore, it is possible to accurately estimate the thermal expansion amount and thermal contraction amount of the main body and the needle valve, and it is possible to appropriately grasp such a change in temperature characteristics.

  (4) The temperature of the portion where the fuel injection valve is attached can be estimated based on the coolant temperature. Therefore, the temperature of the fuel injection valve body is estimated based on the coolant temperature and the estimated fuel temperature. Therefore, the heat transfer of the fuel injection valve body can be modeled with high accuracy, and the temperature of the main body can be estimated with high accuracy.

  (5) The difference between the estimated needle valve temperature and the body temperature is calculated, and the difference between the needle valve temperature and the body temperature is estimated. Accordingly, it is possible to estimate the temperature difference between the two, in which the influence of the detection error of the intake air temperature, the estimation error of the fuel temperature, etc. is eliminated as much as possible, and the estimation accuracy can be suitably ensured.

  (6) The fuel pipe is divided into a plurality of fuel temperature estimation regions, and the fuel temperature estimated in the upstream fuel temperature estimation region is sequentially reflected in the estimation of the fuel temperature in the immediately downstream downstream fuel temperature estimation region. I am doing so. Therefore, it is possible to accurately estimate the fuel temperature in each region in correspondence with the temperature distribution in the entire length direction of the fuel pipe, and thus it is possible to estimate the fuel temperature in the fuel injection valve more accurately.

  Here, in the said embodiment, the site | part where the atmospheric temperature of fuel piping and the temperature of the fuel piping are substantially equal is set to the most upstream fuel temperature estimation area | region. Therefore, the fuel temperature in this fuel temperature estimation region can be estimated easily and accurately, and consequently the fuel temperature in each downstream fuel temperature estimation region estimated sequentially can also be estimated with high accuracy.

  (7) According to the above embodiment, the heat transfer of the fuel in the fuel injection valve and the heat transfer of the fuel injection valve main body can be accurately modeled, and the needle valve and the fuel injection valve main body in the fuel injection valve can be modeled. The temperature can be accurately estimated. Therefore, even if the fuel injection valve for in-cylinder injection, the main body temperature of which tends to be higher than the fuel injection valve for the intake system that injects fuel into the intake passage, the needle valve temperature and the main body temperature Can be estimated with high accuracy.

  (8) The basic fuel injection amount is corrected based on the main body temperature and needle valve temperature of the fuel injection valve accurately estimated in the above-described manner. For this reason, it is possible to suppress a decrease in control accuracy of the fuel injection amount due to the influence of the temperature characteristic of the fuel injection valve.

(9) In particular, the basic fuel injection amount is corrected based on the difference between the main body temperature of the fuel injection valve and the needle valve temperature estimated in the above-described manner. Therefore, even when the fuel injection valve is opened, the clearance CL generated between the needle valve and the fuel injection valve body changes under the influence of temperature, and even if the temperature characteristic of the fuel injection valve changes thereby, The fuel injection amount corresponding to the change can be corrected.
(Second Embodiment)
Next, referring to FIGS. 7 to 10, a second embodiment of the fuel injection valve temperature estimation method and the fuel injection valve correction method using the temperature estimation method according to the present invention will be described. To explain.

  Although the internal combustion engine in the first embodiment is a V-type 6-cylinder engine, an in-line 4-cylinder internal combustion engine is used as an application target engine in the present embodiment. In addition, the delivery pipe 51 in the first embodiment has a substantially U-shape, but the fuel distribution pipe in this embodiment, that is, the delivery pipe has a substantially ladder shape as illustrated in FIG. There is no. The fuel temperature calculation mode is changed in accordance with the change in the fuel flow rate based on the difference in the structure of the delivery pipe. The present embodiment is basically the same as the first embodiment except for these points. Therefore, the following description will focus on differences from the first embodiment.

First, the structure of the delivery pipe 70 will be described.
As shown in FIG. 7, the delivery pipe 70 in this embodiment is composed of two pipes 70a and 70b arranged in parallel and a plurality of communication pipes 70c that connect the pipes 70a and 70b. A high pressure pump 52 is connected to the pipe 70a. Further, the pipe 70a is provided with a fuel injection valve 20 corresponding to each cylinder, and the fuel injection valve 20 for the fourth cylinder # 4 and the fuel for the third cylinder # 3 in order from the side closer to the high pressure pump 52. An injection valve 20, a fuel injection valve 20 for the second cylinder # 2, and a fuel injection valve 20 for the first cylinder # 1 are provided. In addition, the communication pipe 70c is connected in the vicinity of the site where each fuel injection valve 20 is connected in the pipe 70a, and the site where the communication pipe 70c is connected distributes the fuel in the delivery pipe 70. This constitutes a branching section.

  FIG. 8 schematically shows a partial cross-sectional view of a portion of the delivery pipe 70 where the fuel injection valves 20 for the fourth cylinder # 4 and the third cylinder # 3 are attached, and a fuel flow mode in the same portion. ing. As shown in FIG. 8, the fuel sent from the high-pressure pump 52 is diverted at the branch portion 70d near the portion where the fuel injection valve 20 for the fourth cylinder # 4 is provided, and a part of the fuel is It flows into the communication pipe 70c. Further, most of the remaining fuel flows into the pipe 70a on the downstream side of the branch portion 70d, and a very small amount of fuel flows into the fuel injection valve 20 for the fourth cylinder # 4. Thus, the fuel flow rate on the downstream side of the branching portion 70d is different from the fuel flow rate on the upstream side thereof. Therefore, in the present embodiment, the upstream side of the branching portion 70d is set as the above-described region E, and the downstream side of the branching portion 70d is additionally set as a new region F. The fuel in the region E flows into the fuel injection valve 20 for the fourth cylinder # 4, while the fuel in the region F flows into the fuel injection valves 20 for the first cylinder # 1 to the third cylinder # 3. It is supposed to be.

  First, since the fuel in the region E flows into the fuel injection valve 20 for the fourth cylinder # 4, the fuel temperature Tf and the body temperature Ti in the fuel injection valve are the same as those in the first embodiment, that is, Each can be estimated from the following equations shown in [Equation 18].

他方、分岐部７０ｄでの燃料の分配割合について、領域Ｆに流入する燃料の分配割合を分配割合αとすると、領域Ｆの燃料が流入する燃料噴射弁内の燃料温度Ｔｆは次の［数１９］に示される式から推定することができる。

On the other hand, regarding the fuel distribution ratio in the branching portion 70d, if the distribution ratio of the fuel flowing into the region F is the distribution ratio α, the fuel temperature Tf in the fuel injection valve into which the fuel in the region F flows is ] Can be estimated from the equation shown in FIG.

この［数１９］に示される式は上記［数１１］に示した式において、領域Ｘを領域Ｆとして設定するとともに、燃料噴射量Ｑに分配割合αを乗算したものである。

The equation shown in [Equation 19] is obtained by setting the region X as the region F and multiplying the fuel injection amount Q by the distribution ratio α in the equation shown in the above [Equation 11].

  In this way, it is considered that fuel corresponding to the distribution ratio of the fuel amount in the diversion portion is introduced into the fuel injection valve provided on the downstream side of the branch portion. That is, in the present embodiment, in addition to the fuel flow rate (= fuel injection amount) and the piping atmosphere temperature ({KF · Tiold + (1−KF) · THA}), the fuel amount distribution ratio α divided at the branching portion α Based on this, the fuel temperature in the fuel injection valve is estimated. Therefore, the fuel temperature in the fuel injection valve provided on the downstream side of the branch portion can also be estimated with high accuracy.

  Here, the delivery pipe 70 is branched at the branching portion 70d into a pipe 70a having a small degree of change in the fuel flow direction and a communication pipe 70c having a large degree of change. In this case, as the flow rate of the fuel before being diverted increases, more fuel flows into the pipe 70a whose degree of change in the fuel flow direction is small. Therefore, the distribution ratio α can be set based on the fuel flow rate, that is, the fuel injection amount Q.

  For example, the distribution ratio α corresponding to various fuel injection amounts Q as illustrated in FIG. 9 is set in advance so that the distribution ratio α increases as the fuel injection amount Q increases. α can be set. In the present embodiment, the distribution ratio α can be calculated using the equation shown in the following [Equation 20], which is an approximate equation using the fuel injection amount Q correlated with the fuel flow rate as a parameter. The inventor has confirmed that this is possible. Specifically, it has been confirmed that the relationship between the fuel injection amount Q and the distribution ratio α can be expressed using a sigmoid function. Therefore, in this embodiment, the distribution ratio α is set using the equation shown in [Equation 20]. FIG. 10 is a graph showing the correspondence between the fuel injection amount Q and the distribution ratio α represented by this approximate expression.

ここで、「ｅ」は自然対数の底であり、その値は「ｅ＝２．７１８２…」となる無理数である。また、Ｋα２は「分配割合α＝１／２」のときの燃料噴射量Ｑであり、Ｋα１はそのときのグラフの傾きを示している。

Here, “e” is the base of the natural logarithm, and its value is an irrational number such that “e = 2.1821. Kα2 is the fuel injection amount Q when “distribution ratio α = 1/2”, and Kα1 indicates the slope of the graph at that time.

  On the other hand, the main body temperature Ti of the fuel injection valve into which the fuel in the region F flows is obtained by replacing “TfEold” in the equation shown in [Formula 5] with “TfFold” that is the fuel temperature in the region F estimated last time. It can be estimated from the equation shown in the following [Equation 21].

また本実施形態においても、領域Ａ〜領域Ｄにおける燃料温度、及び機関始動直前の各領域における燃料温度、及び機関始動直前における各燃料噴射弁２０の本体温度は、第１の実施形態と同様な態様で推定している。

Also in the present embodiment, the fuel temperature in the regions A to D, the fuel temperature in each region immediately before the engine start, and the body temperature of each fuel injection valve 20 immediately before the engine start are the same as those in the first embodiment. It is estimated in the form.

  When executing the fuel injection amount calculation process as shown in FIG. 6, the main body temperature Ti of the fuel injection valve 20 for the first cylinder # 1 to the fourth cylinder # 4 estimated in this way, and the same fuel The fuel temperature Tf in the injection valve 20, that is, the needle valve temperature Tn is used. Therefore, for each of the fuel injection valves 20 for the first cylinder # 1 to the fourth cylinder # 4, a decrease in the control accuracy of the fuel injection amount due to the influence of the temperature characteristics is suppressed.

  In the present embodiment, the body temperature and fuel temperature (= needle valve temperature) of the fuel injection valves 20 for the first cylinder # 1 and the second cylinder # 2 are also expressed by the above [Equation 21] and [Equation 19]. The present inventor has confirmed that it is possible to accurately estimate using the respective equations shown, but first, the distribution ratio of the fuel at each branch portion is obtained. Further, by estimating the main body temperature and the fuel temperature for the fuel injection valves 20 for the first cylinder # 1 and the second cylinder # 2 based on each distribution ratio, the estimation accuracy can be further improved. Can be planned.

As described above, according to the present embodiment, the following effects can be obtained in addition to the effects obtained by the first embodiment.
(1) The temperature of the fuel flowing into the fuel injection valve tends to decrease as the flow rate of the fuel in the fuel pipe increases. On the other hand, in the fuel distribution pipe to which the fuel injection valve is connected, when a branch portion for distributing the fuel is provided, the fuel injection valve located downstream from the branch portion is distributed to the branch portion. Fuel according to the ratio flows. Therefore, in the above embodiment, in addition to the fuel injection amount correlated with the fuel flow rate and the atmospheric temperature of the fuel pipe, the distribution ratio of the fuel amount to be diverted in the branch portion is further downstream than the branch portion. The fuel temperature in the provided fuel injection valve is estimated. Therefore, the fuel temperature in the fuel injection valve provided on the downstream side of the branching portion can be estimated with high accuracy, and the temperature of the fuel injection valve body can be estimated with high accuracy.

  (2) In the case where the fuel distribution pipe is branched into a fuel pipe having a small degree of change in the fuel flow direction and a fuel pipe having a large change degree compared to the fuel distribution pipe, the fuel before being branched As the flow rate of the fuel increases, more fuel flows into the fuel pipe with a smaller degree of change in the fuel flow direction. Based on such a tendency of the distribution ratio, in the above embodiment, the distribution ratio is obtained based on the fuel injection amount. Accordingly, the distribution ratio α can be set appropriately. In addition, the distribution ratio α is calculated using a function equation that approximates the correspondence between the fuel injection amount and the distribution ratio. Therefore, when obtaining the correspondence between the fuel injection amount and the distribution ratio, the number of man-hours required for the adaptation can be reduced.

In addition, each said embodiment can also be changed and implemented as follows.
In the first embodiment, the fuel pipe is divided into five areas, and in the second embodiment, the fuel pipe system is divided into six areas. However, the number of divisions can be changed as appropriate. .

  In addition, without dividing the fuel pipe into a plurality of regions, the temperature of the fuel flowing into the fuel injection valve is estimated based on at least the ambient temperature of the fuel pipe and the flow rate of the fuel flowing through the pipe, and this estimation The obtained fuel temperature is set as a fuel injection valve body temperature. Further, the main body temperature of the fuel injection valve may be estimated based on the estimated fuel temperature and the temperature of the portion where the fuel injection valve is attached. In this case, the ambient temperature of the fuel pipe, the flow rate of the fuel flowing through the pipe, the temperature of the portion where the fuel injection valve is attached, and the like can be grasped in the same manner as in the first embodiment.

  -In 1st Embodiment, although this invention was applied to the delivery pipe 51 which makes a substantially U shape, the branch part which distributes a fuel to the fuel distribution pipe which distributes the fuel in a fuel pipe to a fuel injection valve is provided. If not, the same effect can be obtained by appropriately adapting each adaptation coefficient in the first embodiment.

  -In 2nd Embodiment, although this invention was applied to the delivery pipe 70 which makes a substantially ladder shape, the branch part which distributes a fuel to the fuel distribution pipe which distributes the fuel in a fuel pipe to a fuel injection valve was provided. In the case of the apparatus, the same effect can be obtained by appropriately adapting the respective adaptation coefficients and distribution ratios in the second embodiment.

  In each of the above embodiments, the temperature of the fuel injection valve due to the change in the gap CL is corrected by correcting the fuel injection amount based on the difference between the main body temperature of the fuel injection valve and the valve body temperature (ie, needle temperature). Compensated for changes in characteristics. Here, according to the present invention, the main body temperature of the fuel injection valve, the valve body temperature, and the fuel temperature in the fuel pipe can be accurately estimated. Therefore, these values are used to inject fuel injection caused by other factors. You may make it compensate the change of the temperature characteristic of a valve. For example, it accurately estimates changes in the temperature characteristics of fuel injectors caused by changes in fuel density due to temperature, changes in temperature characteristics of fuel injectors caused by changes in the amount of vapor generated due to temperature, etc. By correcting the fuel injection amount using each of the above-described temperatures, it is possible to suitably compensate for changes in the temperature characteristics.

-The distribution ratio may be set as a fixed value.
-Although the valve body of the fuel injection valve in each said embodiment was a needle valve, this invention can be applied similarly if it is a fuel injection valve which has a valve body which opens and closes the injection hole of a fuel injection valve.

  In each of the above embodiments, the atmospheric temperature of the fuel pipe is calculated based on the intake air temperature, but may be calculated using other parameters (for example, air temperature in the atmosphere). Moreover, although the flow rate of the fuel flowing through the fuel pipe is calculated from the fuel injection amount, it may be calculated using other parameters. Moreover, although the temperature of the site | part to which the fuel injection valve was attached was estimated based on the cooling water temperature, you may make it also calculate using another parameter (for example, engine body temperature etc.).

  In each of the above embodiments, the temperature of the fuel injection valve 20, in particular, the main body temperature Ti and the needle valve temperature Tn are estimated, but the entire fuel injection valve 20 is based on the fuel temperature flowing into the fuel injection valve 20. The temperature may be estimated.

The tip temperature of the fuel injection valve 20 can also be estimated by correcting the body temperature Ti estimated in the above embodiments based on a predetermined coefficient.
In each of the above embodiments, the fuel injection valve for in-cylinder injection is applied to the present invention. However, the present invention can be similarly applied to the fuel injection valve for the intake system that supplies fuel to the intake passage. it can.

  In the first embodiment, the present invention is applied to a V-type six-cylinder internal combustion engine, and in the second embodiment, an in-line four-cylinder internal combustion engine, but the internal combustion engine having other cylinder arrangements and the number of cylinders. Even so, the present invention can be similarly applied. Further, the present invention can be similarly applied not only to a gasoline engine that ignites an air-fuel mixture with a spark plug, but also to a diesel engine.

The fuel injection valve temperature estimation method and the fuel injection valve injection amount correction method using the temperature estimation method according to the first embodiment of the present invention are exemplified by a fuel pipe of a vehicle on which an internal combustion engine to which the first embodiment is applied is mounted. Schematic to do. Schematic which shows the internal combustion engine and its periphery structure in the embodiment. The conceptual diagram explaining the fuel temperature estimation aspect in the fuel piping in the embodiment. The conceptual diagram which shows the aspect of heat transfer in a fuel injection valve main body. The conceptual diagram which shows the aspect of heat transfer in the fuel in fuel piping. The flowchart which shows the procedure about the calculation process of the fuel injection quantity in the embodiment. Schematic which shows the structure of the delivery pipe in 2nd Embodiment. The conceptual diagram explaining the fuel temperature estimation aspect in the fuel piping in 2nd Embodiment. The graph which shows the correspondence of fuel injection quantity and a distribution ratio in the same embodiment. In the same embodiment, the graph which shows the correspondence of the fuel injection quantity by an approximate expression, and a distribution ratio. The schematic diagram which shows the cross-section of the front-end | tip part of a fuel injection valve.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... Engine room, 10 ... Internal combustion engine, 11 ... Cylinder head, 12 ... Cylinder, 13 ... Cylinder block, 14 ... Piston, 15 ... Combustion chamber, 17 ... Camshaft, 18 ... Intake passage, 19 ... Exhaust 20, fuel injection valve, 20 a, main body, 20 b, needle valve, 20 c, injection hole, 20 d, valve seat, 22, spark plug, 30, crank angle sensor, 31, cam angle sensor, 32, accelerator sensor, 33 ... Water temperature sensor, 34 ... Intake air amount sensor, 35 ... Oxygen sensor, 40 ... Control device, 49 ... Low pressure fuel pipe, 50 ... High pressure fuel pipe, 51 ... Delivery pipe, 52 ... High pressure pump, 53 ... Fuel pump, 54 ... Fuel tank, 55 ... Return pipe, 56 ... Relief valve, 70 ... Delivery pipe, 70a, 70b ... Pipe, 70c ... Communication pipe, 70d ... Kibe.

Claims (11)

Based on the flow rate of fuel flowing from the fuel pipe to the fuel injection valve connected thereto and the temperature of the fuel pipe, the temperature of the fuel flowing into the fuel injection valve is estimated, and based on this, the fuel injection valve is estimated A fuel injection valve temperature estimation method for estimating the temperature of the fuel injection valve,
The fuel distribution pipe to which the fuel injection valve is attached has a branch portion where the fuel is diverted, and when estimating the temperature of the fuel flowing into the fuel injection valve downstream of the branch portion, the flow rate of the fuel is the same. A method for estimating a temperature of a fuel injection valve, wherein the correction is made based on a distribution ratio of a fuel amount diverted at a branching portion . Fuel injection for estimating the temperature of fuel flowing into the fuel injection valve based on the flow rate of fuel flowing from the fuel pipe to the fuel injection valve connected thereto, and estimating the temperature of the fuel injection valve based on the temperature A valve temperature estimation method comprising:
The fuel distribution pipe to which the fuel injection valve is attached has a branch portion where the fuel is diverted, and when estimating the temperature of the fuel flowing into the fuel injection valve downstream of the branch portion, the flow rate of the fuel is the same. Correct based on the distribution ratio of the amount of fuel diverted at the bifurcation
A method for estimating the temperature of a fuel injection valve. The distribution ratio is set based on the fuel flow rate.
The temperature estimation method of the fuel injection valve according to claim 1 or 2 . The temperature estimation method of the fuel injection valve according to any one of claims 1 to 3 , wherein the temperature of the fuel injection valve is estimated based on an ambient temperature of the fuel pipe together with the flow rate of the fuel. The temperature estimation method for a fuel injection valve according to claim 4 , wherein the ambient temperature of the fuel pipe is estimated based on an intake air temperature . The valve body that estimates the temperature of the main body in which the injection hole of the fuel injection valve is formed based on the estimated temperature of the fuel and the temperature of the portion where the fuel injection valve is attached, and opens and closes the injection hole temperature estimation method of the fuel injection valve according to any one of claims 1 to 5 and the body to estimate the individually based on the temperature to the temperature of the fuel to be the estimation. The temperature estimation method for a fuel injection valve according to claim 6 , wherein the temperature of a portion where the fuel injection valve is attached is estimated based on a coolant temperature . The temperature estimation of the fuel injection valve according to claim 6 or 7, wherein the difference between the temperature of the valve body and the temperature of the main body is estimated by calculating the difference between the estimated temperature of the valve body and the temperature of the main body. Method. The fuel pipe is divided into a plurality of fuel temperature estimation areas from a portion where the atmosphere temperature of the fuel pipe can be the pipe temperature to the fuel injection valve, and the fuel estimated in the upstream fuel temperature estimation area temperature estimation method of the fuel injection valve according to any one of claims 1 to 8, adding a temperature as a parameter to be used for temperature estimation of the fuel in the fuel temperature estimation region on the downstream side of the immediately. The temperature estimation method for a fuel injection valve according to any one of claims 1 to 9, wherein the fuel injection valve is an in-cylinder injection fuel injection valve that directly injects fuel into a combustion chamber of an internal combustion engine . The injection amount of the fuel injection valve corresponding to the engine load is corrected based on the temperature of the fuel injection valve estimated by the temperature estimation method for the fuel injection valve according to claim 1.
An injection amount correction method for a fuel injection valve, comprising:

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