JP4888437B2 - Fuel filter replacement time determination device and fuel supply system - Google Patents

Description

  The present invention relates to a fuel filter replacement timing determination device that determines whether or not a replacement time due to clogging has been reached for a fuel filter provided in a fuel supply device that supplies fuel used for combustion of an internal combustion engine to an injector.

  2. Description of the Related Art Conventionally, there has been known a fuel supply device that includes a high-pressure pump that supplies fuel used for combustion of an internal combustion engine to an injector at a high pressure, and a feed pump that supplies fuel in a fuel tank to the high-pressure pump at a low pressure. In general, a fuel filter (see Patent Document 1) is provided in a fuel path from the fuel tank to the high pressure pump. Note that this type of fuel filter has a function of capturing foreign substances contained in the fuel, a function of removing moisture in the fuel, and a function of removing wax components in the fuel.

In such a fuel filter, it is inevitable that clogging will occur with the passage of time of use, and a fuel filter that has been clogged more than a certain amount has a life and requires replacement. Therefore, conventionally, it is determined whether or not the replacement time has been reached based on the travel distance of the vehicle on which the internal combustion engine is mounted, and if it is determined that the replacement time has been reached, a message to that effect is sent to the driver. Notification was made by lighting.
JP-A-11-270425

  However, in the above-described conventional apparatus that periodically performs a prompt to replace the fuel filter based on the travel distance or the like, it is not a replacement time determination according to the actual clogging condition. This means that the fuel filter that has not yet been fully used can be replaced, and there is room for reducing the economic burden on the user.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel filter replacement timing determination device and a fuel supply system capable of determining the replacement timing of a fuel filter according to actual clogging. It is to provide.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

In invention of Claim 1,
A high-pressure pump that supplies fuel used for combustion of the internal combustion engine to the injector at a high pressure; a feed pump that supplies fuel in the fuel tank to the high-pressure pump at a low pressure; and a fuel path from the fuel tank to the high-pressure pump. A fuel filter replacement timing determination device that is applied to a fuel supply device that is disposed and filters a fuel, and that determines a replacement timing due to clogging of the fuel filter;
A fuel pressure sensor disposed in the fuel path for detecting the pressure of the fuel;
A pump rotation speed acquisition means for acquiring a pump rotation speed detection value by a rotation speed sensor for detecting the rotation speed of the feed pump;
A replacement time determination means for determining whether or not the replacement time has been reached based on a fuel pressure detection value that is a detection value of the fuel pressure sensor and the pump rotation speed detection value;
It is characterized by providing.

  In the fuel path from the fuel tank to the high pressure pump, the fuel pressure changes according to the discharge pressure or suction pressure of the feed pump. Further, this pressure also changes depending on the degree of clogging of the fuel filter disposed in the fuel path. That is, it can be said that the fuel pressure in the fuel path changes according to the rotation speed of the feed pump that determines the discharge pressure or the suction pressure and the degree of clogging of the fuel filter. In the invention according to claim 1, which is made paying attention to this point, since it is determined whether or not the replacement time has been reached based on the fuel pressure detection value and the pump rotation speed detection value, the above-mentioned according to the actual clogging degree Judgment can be made. Therefore, it is possible to easily realize that the fuel filter can be used near the end of its life, and it is possible to reduce the economic burden on the user.

  The invention according to claim 2 is given as a specific example of the replacement time determination. That is, the fuel pressure estimation means for estimating the fuel pressure detection value when there is no clogging based on the pump rotation speed detection value is provided, and the replacement timing determination means includes the estimated value by the fuel pressure estimation means and the fuel pressure detection value. The determination is performed on the basis of the deviation amount. It can be said that the amount of deviation is the pressure loss in the fuel filter due to clogging.

  As another specific example of the replacement time determination, the relationship between the pump rotation speed detection value and the determination threshold is stored in advance as a map, the determination threshold is acquired from the pump rotation speed detection value and the map, and the fuel pressure detection value is If the value is lower than the acquired determination threshold value, it may be determined that the replacement time has been reached.

  Here, as described above, the deviation amount indicates the pressure loss in the fuel filter. However, the pressure loss varies depending on the feed pump discharge pressure or the suction pressure even in the same clogged state. In the invention according to claim 3 in view of this point, the replacement time determination means determines that the replacement time has been reached when the deviation amount exceeds a predetermined threshold, and sets the detected value of the pump rotation speed. Accordingly, the threshold value is variably set. Therefore, the accuracy of the replacement time determination can be improved.

  Further, even in the same clogging state, the discharge pressure increases as the pump rotation speed increases, and the deviation amount (pressure loss) increases. Therefore, as the pump rotation speed detection value increases, the threshold value increases. It is desirable to perform the variable setting so as to increase.

  By the way, when the feed pump is configured to rotate using the output shaft of the internal combustion engine as a drive source, the pump rotational speed detection value varies greatly when the operation of the internal combustion engine is in a transient state. And if it is going to perform replacement | exchange time determination based on the pump rotational speed detection value at the time of fluctuating in this way, determination accuracy will worsen. In view of this point, the feed pump is configured to rotate using the output shaft of the internal combustion engine as a drive source, and the fluctuation range of the detected value of the pump rotation speed is within a predetermined range. The replacement time determination means performs the determination on condition that the stable state has continued for a predetermined time or more. Therefore, it is possible to suppress deterioration in determination accuracy due to the fluctuation.

  The invention according to claim 6 is characterized in that the replacement time determination means performs the determination based on an average value of the plurality of detected fuel pressure values acquired in a predetermined period. According to this, since it determines based on an average value, the pulsation and fluctuation | variation of a pump rotational speed detection value will be smoothed, and determination accuracy deterioration can be suppressed.

The invention of claim 7 wherein is a fuel supply system characterized by comprising the above fuel filter replacement-timing determining device, high pressure pump, a fuel supply device having a feed pump, and the fuel filter, the. According to this fuel supply system, the various effects described above can be exhibited in the same manner.

  Hereinafter, an embodiment embodying a fuel filter replacement time determination device according to the present invention will be described with reference to the drawings. In addition, the apparatus of this embodiment is applied to the common rail type fuel supply apparatus which made object the automobile diesel engine (internal combustion engine), for example.

  First, an outline of a common rail fuel injection control system according to the present embodiment will be described with reference to FIG. This system is largely configured such that an ECU (electronic control unit) 30 takes in sensor outputs from various sensors and controls driving of each device constituting the fuel supply system based on the sensor outputs. Yes. The ECU 30 controls the fuel pressure (measured by the rail pressure sensor 22) in the common rail 16 by adjusting the amount of current supplied to the intake adjustment valve (described later in detail) and controlling the fuel discharge amount of the fuel pump 14 to a desired value. Feedback control to the target value (target fuel pressure). Based on the fuel pressure, the fuel injection amount to the predetermined cylinder of the target engine, and thus the output of the engine (the rotational speed and torque of the output shaft) are controlled to a desired magnitude.

  Here, various devices constituting the fuel supply device are arranged in order of the fuel tank 10, the fuel filter 12, the fuel pump 14, the common rail 16, and the injector 20 (fuel injection valve) from the upstream side of the fuel. In this system, the fuel in the fuel tank 10 is pumped by the fuel pump 14 so that the fuel is supplied to the target device in the system.

  Next, with reference to FIG. 2, the detailed structure of the fuel pump 14 and its operation | movement aspect are demonstrated. The fuel pump 14 is basically configured to pressurize and discharge the fuel pumped up from the fuel tank 10 by the feed pump 40 with the high-pressure pump 50. At this time, the amount of fuel sent to the high-pressure pump 50 is adjusted by a suction adjustment valve 60 (SCV: Suction Control Valve) provided on the fuel suction side of the pump 14 (specifically, before the fuel is pumped by the high-pressure pump 50). It has come to be measured.

  Here, the feed pump 40 has an outer rotor on the outer side and an inner rotor on the inner side, and the space created by each of the rotors is increased / decreased according to the rotation of each rotor, and fuel is sucked and discharged according to the increase / decrease. This is a so-called trochoid pump. The pump 40 functions as a so-called low-pressure supply pump that sucks the fuel in the fuel tank 10 from the inlet 42 and sends the fuel to the high-pressure pump 50, and is driven by the rotation of the drive shaft 41. The drive shaft 41 is interlocked with the crankshaft 24 (see FIG. 1), and is driven by power generated by the engine output. That is, the drive shaft 41 is driven as the crankshaft 24 (engine output shaft) rotates, and rotates at a ratio such as “1/1” or “1/2” with respect to one rotation of the crankshaft 24, for example. .

  The fuel sucked up by the feed pump 40 passes through the filter 42a and is sent to the suction adjustment valve 60. At this time, when the discharge pressure of the feed pump 40 exceeds the upper limit value, the regulator valve 43 operates to return the fuel to the fuel tank 10. That is, the discharge pressure of the feed pump 40 is limited (adjusted) to a predetermined pressure or less by the regulator valve 43. Further, the temperature of the fuel sent to the intake adjustment valve 60 can be detected by the fuel temperature sensor 43a.

  The intake adjustment valve 60 is configured to include a normally open linear solenoid type electromagnetic valve that opens when no power is supplied, for example, and adjusts the intake fuel amount of the high-pressure pump 50. The ECU 30 (FIG. 1) controls the energization time (supply current amount) for the intake adjustment valve 60 so that the amount of fuel drawn from the feed pump 40 to the high-pressure pump 50 through the fuel passage 44 can be adjusted. It has become. That is, the fuel sent by the feed pump 40 is adjusted to a required discharge amount (target fuel pressure feed amount) by the suction adjusting valve 60 and flows into the high-pressure pump 50 through the suction valve 53 (suction valve). .

  The high-pressure pump 50 is a plunger pump that pressurizes the fuel metered by the suction adjustment valve 60 and discharges the fuel to the outside. The high-pressure pump 50 is mainly configured to include a plunger 51 that is driven to reciprocate by the drive shaft 41, and a pressurizing chamber 52a formed between the inner wall 52b of the housing 52 and the tip end surface of the plunger 51. The volume of the pressurizing chamber 52a (plunger chamber) changes due to the reciprocating motion of the plunger 51 in the axial direction.

  The plunger 51 is pressed against a ring cam 56 mounted around the eccentric cam 55 by a spring 57. The eccentric cam 55 is attached to the drive shaft 41 so as to be eccentric. When the drive shaft 41 rotates, the eccentric cam 55 rotates eccentrically, and the ring cam 56 follows and displaces the plunger 51 as a shaft. Push (or pull) in the direction to displace. In this way, the two plungers 51 reciprocate between the pumping top dead center and the pumping bottom dead center.

  As described above, on the suction side of the high-pressure pump 50, the suction valve 53 that connects or blocks the pressurizing chamber 52a and the feed pump 40 side is disposed. On the other hand, a discharge valve 54 is also provided on the discharge side of the high-pressure pump 50 to communicate or block the pressurizing chamber 52a and the common rail 16 side. That is, when the volume of the pressurizing chamber 52a increases with the lowering of the plunger 51 and the pressure in the pressurizing chamber 52a decreases, the discharge valve 54 closes and the suction valve 53 opens. As a result, fuel is supplied from the feed pump 40 into the pressurizing chamber 52 a via the suction adjustment valve 60. Conversely, when the volume of the pressurizing chamber 52a decreases as the plunger 51 rises and the pressure in the pressurizing chamber 52a increases, the suction valve 53 is now closed. When the pressure in the pressurizing chamber 52a reaches a predetermined pressure, the discharge valve 54 is opened, and the high-pressure fuel pressurized in the pressurizing chamber 52a is supplied toward the common rail 16. As described above, when the fuel pump 14 is operated, the fuel in the fuel tank 10 is pumped up through the fuel filter 12 and pressurized (suppressed) to the common rail 16.

  The common rail 16 stores the fuel pumped from the fuel pump 14 in a high pressure state and stores the fuel in a high pressure pipe 18 provided in each of the cylinders # 1 to # 4 to the injector 20 (fuel injection valve) of each cylinder. Each one is to be supplied. The injector 20 is provided for each combustion chamber in each of the cylinders # 1 to # 4, and is configured as a fuel injection valve for high-pressure fuel that injects high-pressure fuel accumulated and held in the common rail 16. It is what is done. The surplus fuel supplied to the injector 20 is returned to the fuel tank 10 through the low-pressure pipe 28.

  Next, the fuel filter 12 shown in FIG. 1 will be described in detail.

  The fuel filter 12 is disposed in the middle of a pipe 29 that connects the fuel pump 14 and the fuel tank 10. That is, it is disposed on the fuel path from the fuel tank 10 to the feed pump 40. The fuel filter 12 is configured by housing a filter element 12b in a case 12a. The filter element 12b has a function of capturing foreign matter contained in the fuel, a function of removing moisture in the fuel, and It has a function of removing the wax component in the fuel.

  In such a fuel filter 12, the trapped foreign matter, wax component, and the like accumulate on the filter element 12b and become clogged over time. The filter element 12b having a certain level of clogging has a lifetime and needs to be replaced. Therefore, in this embodiment, the fuel pressure sensor 13 for detecting the pressure of the fuel is installed on the downstream side of the fuel filter 12 and the upstream side of the feed pump 40, and the ECU 30 (fuel filter replacement timing determination device) detects the detected value of the fuel pressure sensor 13. Based on the detected fuel pressure value and the rotational speed Np of the feed pump 40, it is determined whether or not the replacement time due to clogging has been reached (hereinafter, this determination is referred to as “replacement time determination”).

  FIG. 3 is a flowchart showing a processing procedure of replacement time determination executed by the microcomputer provided in the ECU 30, and this processing is repeatedly executed every predetermined time (for example, a calculation cycle of the CPU of the microcomputer) during engine operation. .

  The ECU 30 receives a crank angle signal from a crank angle sensor 24a (rotational speed sensor) that detects the rotation angle of the crankshaft 24. In step S10 of FIG. 3, the rotational speed of the crankshaft 24 (engine rotational speed Ne) is calculated based on the acquired crank angle signal. In the subsequent step S20 (pump rotation speed acquisition means), the rotation speed Np (pump rotation speed detection value) of the feed pump 40 is calculated based on the calculated engine rotation speed Ne.

  Here, since the feed pump 40 rotates using the crankshaft 24 as a drive source, if the engine rotational speed Ne varies, the pump rotational speed Np also varies, and the discharge pressure and the suction pressure by the feed pump 40 vary. Regarding the fluctuation of the pump rotation speed Np generated in this way, in the subsequent step S30, it is determined whether or not the fluctuation is in a stable state. Specifically, it is determined whether or not the stable state where the fluctuation range of the calculated pump rotation speed Np is within a predetermined range has continued for a predetermined time or more.

  If it is determined that it is not in a stable state (S30: NO), it waits until it is in a stable state, and if it is determined that it is in a stable state (S30: YES), then in step S40 (fuel pressure estimating means), step S20 is performed. Based on the calculated pump rotation speed Np, the fuel pressure detection value of the fuel pressure sensor 13 when the fuel filter 12 is not clogged is estimated. That is, the fuel pressure when there is no clogging on the upstream side of the feed pump 40 and the downstream side of the fuel filter 12 is estimated.

  For the estimation in step S40, a map for specifying the relationship between the pump rotation speed Np and the estimated value may be used, or an arithmetic expression for calculating the estimated value from the pump rotation speed Np may be used. These maps and arithmetic expressions may be set in advance by a test or the like and stored in a storage device such as a microcomputer ROM. A solid line (2) in FIG. 4 indicates the estimated value in step S40 when the map is used, and it is estimated that the estimated value increases as the pump rotation speed Np increases.

  In subsequent step S50, a detection value (fuel pressure detection value) by the fuel pressure sensor 13 is acquired. This fuel pressure sensor 13 detects the actual fuel pressure at the location (upstream of the feed pump 40 and downstream of the fuel filter 12) estimated in step S40. As the clogging of the fuel filter 12 progresses, the detected fuel pressure value becomes lower even if the pump rotational speed Np is the same (see the dotted line (1) in FIG. 4). Therefore, it can be said that the amount of deviation of the fuel pressure detection value from the estimated fuel pressure value (see (3) in FIG. 4) when there is no clogging is the pressure loss in the fuel filter 12.

  In view of this point, in the subsequent step S60, the pressure loss in the fuel filter 12 is calculated by subtracting the detected fuel pressure value acquired in step S50 from the estimated value estimated in step S40. In subsequent step S70 (replacement time determination means), it is determined whether or not the calculated pressure loss is larger than a preset clogging determination threshold value, and if it is determined that "pressure loss> threshold value". (S70: YES), it is determined that the filter element 12b has reached the replacement time due to clogging.

  The clogging determination threshold value is variably set according to the pump rotation speed Np. Specifically, the clogging determination threshold value is variably set so as to increase as the pump rotation speed Np increases. This is because even if the degree of clogging of the fuel filter 12 is the same, the deviation (3) increases as the value of the pump rotational speed Np increases. Incidentally, for this variable setting, a map for specifying the relationship between the pump rotation speed Np and the determination threshold value may be used, or an arithmetic expression for calculating the determination threshold value from the pump rotation speed Np may be used. These maps and arithmetic expressions may be set in advance by a test or the like and stored in a storage device such as a microcomputer ROM.

  If it is determined that the replacement time has been reached (S70: YES), a notification means such as turning on a lamp provided on the instrument panel in the vehicle interior so as to prompt replacement of the filter element 12b in step S80. To inform the vehicle driver.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) Based on the feed pump rotational speed Np, the fuel pressure detection value of the fuel pressure sensor 13 when the filter element 12b is not clogged is estimated. And based on the deviation | shift amount of the said estimated value and the fuel pressure detection value detected by the fuel pressure sensor 13, the pressure loss amount in the filter element 12b is calculated, and when the calculated pressure loss amount is larger than the determination threshold value, the filter element It is determined that 12b has reached the replacement time. Therefore, in the past, the filter element 12b was periodically replaced for each specified travel distance, whereas in the present embodiment, it is possible to perform replacement time determination and replacement prompt notification according to the actual clogging condition. Therefore, it is possible to easily realize that the filter element 12b can be used to near the end of its life, and it is possible to reduce the economic burden on the user.

  (2) Even if the degree of clogging of the fuel filter 12 is the same, the deviation (3) increases as the value of the pump rotational speed Np increases. Therefore, in the present embodiment, since the clogging determination threshold value is variably set so as to increase as the pump rotation speed Np increases, the accuracy of replacement time determination can be improved.

  (3) The replacement time determination in steps S40 to S70 is performed on the condition that the stable state in which the fluctuation range of the pump rotation speed Np caused by the fluctuation of the engine rotation speed Ne is within the predetermined range has continued for a predetermined time or more. , Deterioration in accuracy of the determination can be suppressed.

(Other embodiments)
The above embodiments may be implemented with the following modifications. Further, the present invention is not limited to the description of the above embodiment, and each characteristic configuration according to each of the following embodiments may be arbitrarily combined.

  In calculating the fuel pressure detection value based on the pump rotation speed Np in step S40 of FIG. 3, the average value of a plurality of pump rotation speeds Np acquired during a predetermined period is calculated, and the fuel pressure detection value is estimated based on the average value By doing so, the pulsation and fluctuation of the pump rotation speed Np are smoothed, and deterioration of the determination accuracy can be suppressed.

  If the detected fuel pressure value used in step S60 in FIG. 3 is an average value of a plurality of detected fuel pressure values acquired in a predetermined period, the pulsation and fluctuation of the detected fuel pressure value will be smoothed, and deterioration in determination accuracy can be suppressed. .

  1 is disposed on the upstream side of the feed pump 40, but may be disposed on the downstream side of the feed pump 40 and the upstream side of the high-pressure pump 50. Even in this case, it is desirable that the fuel pressure sensor 13 is disposed on the downstream side of the fuel filter 12. Although the fuel pressure sensor 13 may be arranged on the upstream side of the fuel filter 12, the amount of deviation appears more markedly depending on the clogging of the fuel filter 12 when arranged on the downstream side, so that the determination accuracy can be improved.

  The fuel pressure sensor 13 shown in FIG. 1 is disposed on the downstream side of the fuel filter 12, but may be disposed on the upstream side of the fuel filter 12. In this case, the fuel pressure detection value on the upstream side of the fuel filter 12 when the fuel filter 12 is not clogged is estimated based on the feed pump rotational speed Np, and the amount of deviation between the estimated value and the fuel pressure detection value is estimated. The replacement time may be determined based on whether or not the determination threshold is exceeded. However, since the amount of deviation appears more markedly when the fuel filter 12 is clogged, the determination accuracy can be improved.

  The fuel pressure sensor 13 shown in FIG. 1 is attached to the case 12a of the fuel filter 12. More specifically, it is attached to the fuel outlet portion of the case 12a. The fuel pressure sensor 13 of the present invention is not limited to the arrangement attached to the case 12a. For example, the fuel pressure sensor 13 may be attached to the pipe 29 connecting the fuel pump 14 and the fuel tank 10, or may be the inlet 42 of the fuel pump 14. The fuel temperature sensor 43a may be integrated with the fuel temperature sensor 43a.

  The determination threshold value used in step S70 may be variably set according to the fuel temperature detected by the fuel temperature sensor 43a.

1 is a diagram showing a common rail fuel injection control system to which a fuel filter replacement timing determination device according to an embodiment of the present invention is applied. The figure which shows the detailed structure of the fuel pump used for the system. The flowchart which shows the process sequence of the replacement time determination performed by ECU of FIG. The figure which shows the relationship of the pressure loss in the fuel pressure estimated value, fuel pressure detected value, and fuel filter in the case of not clogging calculated by the process of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fuel tank, 12 ... Fuel filter, 13 ... Fuel pressure sensor, 20 ... Injector, 30 ... ECU (fuel filter replacement time determination device), 40 ... Feed pump, 43 ... Regulator valve, 50 ... High pressure pump, S20 ... Pump rotation Speed acquisition means, S40 ... fuel pressure estimation means, S70 ... replacement time determination means.

Claims (7)

A high-pressure pump that supplies fuel used for combustion of the internal combustion engine to the injector at a high pressure; a feed pump that supplies fuel in the fuel tank to the high-pressure pump at a low pressure; and a fuel path from the fuel tank to the high-pressure pump. A fuel filter replacement timing determination device that is applied to a fuel supply device that is disposed and filters a fuel, and that determines a replacement timing due to clogging of the fuel filter;
A fuel pressure sensor disposed in the fuel path for detecting the pressure of the fuel;
A pump rotation speed acquisition means for acquiring a pump rotation speed detection value by a rotation speed sensor for detecting the rotation speed of the feed pump;
A replacement time determination means for determining whether or not the replacement time has been reached based on a fuel pressure detection value that is a detection value of the fuel pressure sensor and the pump rotation speed detection value;
A fuel filter replacement time determination device comprising: Based on the pump rotation speed detection value, provided with a fuel pressure estimation means for estimating the fuel pressure detection value in the case of clogging,
2. The fuel filter replacement time determination device according to claim 1, wherein the replacement time determination unit performs the determination based on a deviation amount between an estimated value from the fuel pressure estimation unit and the detected fuel pressure value.   The replacement time determining means determines that the replacement time has been reached when the deviation amount exceeds a predetermined threshold value, and variably sets the threshold value according to the pump rotation speed detection value. The fuel filter replacement time determination device according to claim 1 or 2.   The fuel filter replacement time determination device according to claim 3, wherein the replacement time determination means performs the variable setting so that the threshold value increases as the pump rotation speed detection value increases. The feed pump is configured to rotate using the output shaft of the internal combustion engine as a drive source,
5. The replacement time determination means performs the determination on the condition that a stable state in which a fluctuation range of the pump rotation speed detection value is within a predetermined range has continued for a predetermined time or more. The fuel filter replacement time determination device according to any one of the above.   6. The fuel filter replacement time determination according to claim 1, wherein the replacement time determination unit performs the determination based on an average value of the plurality of detected fuel pressure values acquired during a predetermined period. apparatus. A fuel filter replacement time determination device according to any one of claims 1 to 6,
A fuel supply device having the high-pressure pump, the feed pump, and the fuel filter,
A fuel supply system comprising:

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