JP6365399B2 - Function check method of injection quantity measuring device - Google Patents

Description

  The present invention relates to a function check method for an injection amount measuring device.

  Conventionally, as shown in Patent Document 1, an injection amount measuring apparatus that measures an injection amount using the Zeuch method is known. The injection amount measuring device is used for a test for developing a fuel injection valve and for measuring an injection amount for quality evaluation of the fuel injection valve.

This injection amount measuring device includes a pressure vessel having a measurement chamber therein and a pressure sensor for detecting the pressure in the measurement chamber. The measurement chamber is filled with fuel, and a fuel injection valve is attached to the container via an adapter. When the fuel to be measured is injected from the fuel injection valve into the measurement chamber, the pressure in the measurement chamber increases, and the pressure increase amount ΔP at this time is expressed by the following equation (1).
ΔP = K (Q / V) (1)

  Here, K is the bulk modulus of fuel in the measurement chamber, Q is the injection amount, and V is the volume of the measurement chamber at the time of fuel injection. Therefore, if this pressure increase amount ΔP is detected based on the detection result of the pressure sensor, the injection amount Q can be calculated based on the equation (1).

JP 2001-123917 A

  In such an injection amount measuring apparatus, in order to check whether the pressure sensor is functioning correctly, a periodic check is performed by removing the pressure sensor and checking the linearity with a tester. However, there is a problem that a strict check is not performed because the check is performed in an environment different from the actual use environment.

  More specifically, a resin seal portion is formed around an adapter to which the fuel injection valve is attached in the pressure vessel, and a safety valve or the like is also attached to the pressure vessel. Since these members are elastically deformed at the time of fuel injection, the overall elastic modulus of the pressure vessel changes in an actual use environment. In addition, the characteristics of the pressure sensor change when a tightening force is applied during installation.

  For this reason, it is important to check the linearity of the pressure sensor in the usage environment attached to the pressure vessel. In addition, since the timing at which the pressure sensor fails is unknown, it is desirable to perform an appropriate function check and measure the correct injection amount.However, if the pressure sensor is removed for each check, the equipment will be stopped. There was also a problem that occurred frequently and deteriorated productivity.

  The present invention was created in view of the above points, and an object thereof is to provide a function check method for an injection amount measuring apparatus capable of improving function check accuracy without deteriorating productivity. There is to do.

  The function check method of the injection amount measuring apparatus according to the present invention includes a first approximate linear equation calculation stage and a first linearity determination stage.

  The injection amount measuring device injects the measurement liquid from the liquid injection valve toward the measurement chamber, the pressure container that forms the measurement chamber filled with the measurement liquid, the first pressure sensor that detects the pressure in the measurement chamber, and the like. A discharge means for discharging a volume of measurement liquid corresponding to the pressure increase amount of the measurement chamber from the measurement chamber, a volume flow meter for measuring the volume flow rate of the measurement liquid discharged from the discharge means as an injection amount, and a liquid injection valve And a control unit for controlling the operation of the discharging means.

  In the first approximate linear calculation stage, in the injection by the master liquid injection valve capable of injecting the measurement liquid of the reference volume, the measured injection amount and the first pressure measured as the injection amount by the volume flow meter for each of a plurality of measurement injection conditions From the relationship of the amount of pressure rise detected by the sensor, the control unit calculates an expression of a first approximate straight line indicating the linearity of the first pressure sensor.

  In the first linearity determination step, the control unit determines the linearity of the first pressure sensor based on whether or not the difference between the first approximate line and the measured injection amount is within an error range.

  According to this method, in the injection using the master liquid injection valve, whether or not the difference between the expression of the first approximate straight line and the actual measured injection amount is within a predetermined error range, It is possible to determine whether the first pressure sensor maintains sufficient accuracy when detecting pressure. And since the linearity is seen in the use environment state where the 1st pressure sensor was attached to the pressure vessel, the function check precision of an injection quantity measuring device can be improved. In addition, since there is no need to remove the first pressure sensor from the apparatus, the function check can be performed in a short time, and the productivity of the injection amount measuring apparatus can be improved comprehensively.

The schematic diagram which shows the whole structure of the injection quantity measuring device. The flowchart which shows injection amount calculation control. The flowchart which shows a periodic function check control. The figure which shows a primary approximation straight line with the injection amount on the horizontal axis and the pressure increase on the vertical axis. The flowchart which shows real-time function check control. The figure which shows typically the pressure fluctuation in the measurement chamber detected by the 1st pressure sensor. The figure which shows typically the pressure fluctuation in the measurement chamber detected by the 2nd pressure sensor. The figure which shows typically the superimposition of the data after correction | amendment of a 1st pressure sensor, and the 2nd data by a 2nd pressure sensor.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
[Constitution]
A function check method of the injection amount measuring apparatus 1 according to the first embodiment of the present invention will be described with reference to FIGS. First, FIG. 1 will be referred to regarding the configuration of the injection amount measuring apparatus 1. The ejection amount measuring device 1 is a device that measures the flow rate of the measurement liquid ejected from the injector 101 as the liquid ejection valve to be measured. The injection amount measuring apparatus 1 includes a pressure vessel 20, a high pressure pump 21, a common rail 22, a first pressure sensor 23, a second pressure sensor 24, a solenoid valve 25, a regulator 26, a volume flow meter 27, a control unit 28, and the like.

  The pressure vessel 20 has a measurement chamber 29 inside, and temporarily stores the fuel injected from the injector 101 arranged facing the measurement chamber 29. The measurement chamber 29 is prefilled with fuel before injection. The pressure before injection in the measurement chamber 29 is adjusted by a regulator 26 described later.

  The first pressure sensor 23 and the second pressure sensor 24 detect the pressure in the measurement chamber 29, and output a signal corresponding to the pressure in the measurement chamber 29 to the control unit 28. The first pressure sensor 23 is a piezoresistive semiconductor pressure sensor, and is usually used to detect a pressure change during fuel injection when measuring a one-shot flow rate or a multistage injection flow rate. The second pressure sensor 24 is a metal diaphragm type pressure sensor, and its output signal is usually used to maintain the inside of the measurement chamber 29 at a set pressure.

  The high-pressure pump 21 pumps fuel from a tank (not shown) that accumulates fuel, pressurizes the fuel, and supplies the pressurized fuel to the common rail 22. The common rail 22 temporarily stores the fuel pressurized by the high-pressure pump 21 and supplies the fuel to the injector 101 connected via a pipe. The common rail 22 is provided with a pressure sensor (not shown), and the fuel pressure in the common rail 22 is set to an arbitrary set pressure by controlling the discharge amount of the high-pressure pump 21.

  The electromagnetic valve 25 is opened and closed by a command signal from the control unit 28 and is provided between the pressure vessel and the regulator 26. When the electromagnetic valve 25 is opened for a predetermined time, the fuel in the measurement chamber 29 is discharged to the outside, and the pressure in the measurement chamber 29 decreases.

  The regulator 26 is for holding the pressure in the measurement chamber 29 at a set pressure. When the pressure in the measurement chamber 29 exceeds the set pressure, the volume of fuel corresponding to the pressure is opened from the measurement chamber 29 by opening the electromagnetic valve 25. For example, the set pressure of the regulator 26 is set to about several MPa.

  The volume flow meter 27 is disposed on the downstream side of the regulator 26, measures the flow rate of fuel discharged from the regulator 26 and passes through the volume flow meter 27, and outputs a signal corresponding to the flow rate to the control unit 28. . In addition, what was measured as the injection amount by the volume flow meter 27 corresponds to the “measurement injection amount” described in the claims.

  The control unit 28 is composed of a microcomputer centering on a CPU, ROM, RAM, flash memory, and the like. The control unit 28 is electrically connected to the high-pressure pump 21, the common rail 22, the first pressure sensor 23, the second pressure sensor 24, the electromagnetic valve 25, and the volume flow meter 27. The control unit 28 controls the rotation of the high-pressure pump 21, the injection timing and injection amount of the injector 101, and the opening / closing of the electromagnetic valve 25 in accordance with a plurality of measurement injection conditions. Further, the control unit 28 executes various arithmetic processes based on the detection data detected by the pressure sensors 23 and 24.

[Injection amount measurement method]
Next, an injection amount measuring method by the injection amount measuring apparatus 1 having the above configuration will be described. FIG. 2 is a flowchart illustrating an example of injection amount measurement control executed by the control unit 28. This injection amount measurement control is executed after the injector 101 to be measured is attached to the pressure vessel 20 and the fuel in the measurement chamber 29 is filled. The electromagnetic valve 25 is closed and the measurement chamber 29 is sealed.

As shown in FIG. 2, first, in step 1 (hereinafter, “step” is abbreviated as S), the inside of the measurement chamber 29 is set to a set pressure. Next, in S2, fuel is injected from the injector 101 under a predetermined condition for measuring the injection amount. Next, in S <b> 3, the pressure increase amount ΔP generated by the fuel injection is detected from the output signal of the first pressure sensor 23. Next, in S <b> 4, the electromagnetic valve 25 is opened for a predetermined time, and the injected volume of fuel is discharged from the measurement chamber 29. The valve opening time of the electromagnetic valve 25 is determined so that the pressure in the measurement chamber 29 after being opened becomes the set pressure. Next, in S5, the injection amount Q is calculated by the following equation (1) based on the pressure increase amount ΔP.
ΔP = K (Q / V) (1)

  Here, K is the bulk modulus of the fuel in the measurement chamber 29, and V is the volume of the measurement chamber 29 at the time of fuel injection. That is, the injection amount Q of the injector 101 is calculated based on the pressure increase amount ΔP, the bulk modulus K, and the volume V of the measurement chamber 29. In practice, injection is repeated for several tens of shots under the same injection condition, and the injection amount Q is calculated after taking the average value of the obtained pressure increase amounts ΔP. In addition, for example, 10 or more conditions are set for one injector 101, the supply pressure by the common rail 22 is appropriately changed, and the injection amount of the injector 101 is changed within the same supply pressure.

[Regular function check method]
Next, a periodic function check method of the injection amount measuring apparatus 1 having the above configuration will be described. In the present embodiment, a failure diagnosis method for diagnosing a failure of the pressure sensors 23 and 24 included in the injection amount measuring device 1 will be specifically described as a function check. The first embodiment is a method in a periodic check using the master injector 102 as a pre-stage for measuring the injection amount of the injector 101 as a product in a mass production manner. In FIG. 1, a master injector 102 is disposed in the pressure vessel 20. The master injector 102 can inject a predetermined volume of fuel serving as a reference, and the injection amount under each injection condition is guaranteed.

  FIG. 3 is a flowchart illustrating an example of the periodic function check control executed by the control unit 28. This periodic function check control is executed after the master injector 102 is attached to the pressure vessel 20 and the measurement chamber 29 is filled with fuel. This control is executed in the same manner for each of the pressure sensors 23 and 24. In the following description, the first pressure sensor 23 will be described as an example. First, in S21, multilevel (for example, four levels) injection conditions with different injection amounts are set. In S22, under the respective injection conditions, the injection amounts Q1, Q2, Q3, and Q4 are measured from the volume flow meter 27, and the pressure increase amounts ΔP1, ΔP2, ΔP3, and ΔP4 are measured from the first pressure sensor 23. As the pressure increase amount ΔP, injection is repeated about several tens of shots under the same injection conditions, and an average value of the obtained pressure increase amounts ΔP is adopted.

Next, in S23, an equation of the first approximate straight line L is calculated from the measured values at the injection amount Q1 that is the minimum injection amount and the injection amount Q4 that is the maximum injection amount among the respective levels. FIG. 4 is a diagram showing a first approximate straight line L with the injection amount Q on the horizontal axis and the pressure increase amount ΔP on the vertical axis. The expression of the first approximate straight line L is expressed by the following expression (2).
ΔP = A × Q + B (2)

  Here, A and B are calculated predetermined coefficients. Returning to the flowchart of FIG. 3, in S24, the difference D2 between the calculated values ΔPc2 and ΔPc3 obtained by substituting the measured injection amounts Q2 and Q3 into the equation of the first approximate straight line L and ΔP2 and ΔP3 obtained by actual measurement. , D3 and the difference D2, D3 and the error Err are determined. The error Err is set to a predetermined value for each of the sensors 23 and 24. If both the differences D2 and D3 are within the range of the error Err shown in FIG. 4, the function can be determined to be normal. For example, any of the differences D2 and D3 Can be determined to be abnormal when the error is outside the range of the error Err.

  Thus, failure diagnosis of each pressure sensor 23, 24 is performed by so-called linearity. The second pressure sensor 24 is executed as S31 to S34 in the same manner as described above, and the calculated value obtained by substituting the equation of the second approximate line in S34 and calculating the equation of the second approximate line in S33. The function is determined based on the difference from the actual measurement value. The process of S23 in the present embodiment corresponds to a “first approximate linear expression calculation stage” recited in the claims, and the process of S33 corresponds to a “second approximate linear expression calculation stage”. Further, the process of S24 corresponds to a “first linearity determination stage” recited in the claims, and the process of S34 corresponds to a “second linearity determination stage”.

[effect]
(1) According to the present embodiment, the master injector 102 is used to check the linearity in the usage environment state in which the pressure sensors 23 and 24 are attached to the pressure vessel 20. Compared with the case where it does, the linearity of the pressure sensors 23 and 24 can be grasped | ascertained more correctly.

  (2) Since the timing at which the pressure sensors 23 and 24 fail is unknown, it is desirable to check the function appropriately. However, if the pressure sensors 23 and 24 are removed for each check, the injection amount measuring device 1 may deteriorate the productivity. However, according to the method of the present invention, since there is no need to remove the pressure sensors 23 and 24 from the apparatus, the function check can be performed in a short time, and the efficiency as the injection amount measuring apparatus 1 is not deteriorated. Functional check can be performed.

Second Embodiment
[Real-time function check method]
Next, a function check method of the injection amount measuring apparatus 1 according to the second embodiment of the present invention will be described with reference to FIGS. The second embodiment is a method of performing a function check in real time during operation of equipment that measures the injection amount of the injector 101 in a mass production manner. As a premise, it is assumed that the periodic check in the first embodiment has been performed and the linearity of each pressure sensor 23, 24 is guaranteed.

  Since the configuration of the injection amount measuring device 11 and the injection amount measurement control are the same as those in the first embodiment, description thereof will be omitted. In the present embodiment, injection amount measurement is performed on a single injector 101 under a plurality of injection conditions. When the injection amount measurement is completed for one injector 101, the injector 101 is removed from the pressure vessel 20, the next injector 101 is attached to the pressure vessel 20, and the injection amount measurement is continuously performed.

  In this embodiment, the pressure check during fuel injection is detected by two different pressure sensors 23 and 24, respectively, and the linearity is compared to check the function of the pressure sensors 23 and 24 during operation of the equipment in real time. The point to be done in is the feature.

  FIG. 5 is a flowchart illustrating an example of real-time function check control. This real-time function check control is executed after the injector 101 to be measured is attached to the pressure vessel 20 and fuel injection is performed by the injector 101 in a state where the measurement chamber 29 is filled with fuel. As shown in FIG. 5, the pressure increase amount ΔP under each injection condition is acquired in S41. As the pressure increase amount ΔP, the average value of the pressure increase amounts ΔP obtained by repeating the injection about several tens of shots under the same injection condition is adopted.

  As shown in the first data W1 in FIG. 6 and the second data W2 in FIG. 7, when fuel is injected into the measurement chamber 29, the pressure in the measurement chamber 29 increases by ΔP. The first data W1 is an output value of the first pressure sensor 23, and the second data W2 is an output value of the second pressure sensor 24. Further, the average value of the pressure increase amount ΔP detected by the first pressure sensor 23 is similarly used in S3 in the injection amount calculation control shown in FIG. 2, and the injection amount calculation control is executed simultaneously with this control. The

Referring to the flowchart of FIG. 5 again, after obtaining the pressure increase amount ΔP, in S42, the first data W1 is corrected using the conversion factors KA and KB. KA is a correction value for the slope of the detected waveform, and KB is a correction value for the vertical translation of the detected waveform. The corrected data W1c is obtained by the following equation (3) as a value obtained by multiplying the first data W1 by KA and adding KB.
W1c = W1 × KA + KB (3)

Here, the conversion factors KA and KB are obtained from the data at the time of the periodic check. From the equation (2), it is assumed that the primary approximate line of the first pressure sensor 23 is represented by the following equation (4).
ΔP = A1 × Q + B1 (4)

Similarly, the primary approximate straight line of the second pressure sensor 24 is expressed by the following equation (5).
ΔP = A2 × Q + B2 (5)
At this time, the conversion coefficient KA is expressed by the following equation (6).
KA = A2 / A1 (6)
The conversion coefficient KB is expressed by the following equation (7) using the pressures P1, P2 in the measurement chamber 29 immediately before the injection and the conversion coefficient KA measured by the sensors 23, 24 as shown in FIGS. Is done.
KB = P2− (KA × P1) (7)

  In S43, the corrected data W1c and the second data W2 are overlapped to obtain a difference between the two data, and it is determined whether or not the difference is within an error range. As shown in FIG. 8, the difference at time t1 immediately before fuel injection and the difference at time t2 after the post-injection pressure is stabilized are taken. If this difference is within a predetermined error range, it is determined that the linearity of both sensors 23 and 24 is maintained. If the difference is outside the error range, it is determined that the linearity of any sensor is impaired. That is, it is understood that the calculated injection amount in this state is not accurate due to a failure of one of the pressure sensors 23 and 24 and is not a failure of the injector 101.

  The process of S42 in this embodiment corresponds to the “correction stage” described in the claims, and the process of S43 corresponds to the “comparison determination stage” described in the claims.

  According to the present embodiment, the same effects as those of the first embodiment can be obtained. Furthermore, in this embodiment, there exist the following effects. The linearity of the first pressure sensor 23 and the second pressure sensor 24 is guaranteed by the first linearity determination step in S24 and the second linearity determination step in S34 in the injection by the master injector 102. If the sensors have guaranteed linearity, their detection waveforms should overlap by multiplying by an appropriate conversion factor. Therefore, the difference between the pressure value corrected by using an appropriate conversion coefficient for the detection waveform of one sensor 23 and the pressure value of the other sensor 24 is taken. It can be determined that the linearity is impaired.

  In the present embodiment, the output waveform of the first pressure sensor 23 is corrected and overlapped with the detection waveform of the second pressure sensor 24. In this way, by using the existing two sensor outputs and monitoring each other's sensors 23 and 24, in the injection of the injector 101 as the measurement target, the pressure sensor is calculated in real time while calculating the injection amount of the injector 101. 23 and 24 function checks can be performed.

  In the past, only the injection amount of the injector 101 could be checked. However, the measured value of the injection amount is out of the standard due to the failure of the pressure sensors 23 and 24, not the failure of the injector 101. Can be grasped. Thus, by performing the function check of the injection amount measuring device 1, the quality of the injector 101 is secured.

<Other embodiments>
In the first embodiment, four levels of injection conditions with different injection amounts are set in S21 shown in FIG. 3, but not limited to the four levels, it may be a plurality of conditions of at least three levels.

  In the second embodiment, the output value from the first pressure sensor 23 is corrected using the conversion factors KA and KB. However, the output value from the first pressure sensor 23 remains unchanged, and the output from the second pressure sensor 24 remains unchanged. The value may be corrected. In this case, a conversion coefficient based on the first pressure sensor 23 may be calculated in advance and corrected based on the conversion coefficient.

  In the second embodiment, the two pressure sensors 23 and 24 are configured by sensors having different types of measurement principles, but may be a plurality of pressure sensors of the same type. For example, when two piezoresistive semiconductor pressure sensors are provided for detecting the amount of pressure increase in the measurement chamber 29, the two pressure sensors may be monitored with each other. If the ranges are substantially the same, the conversion factor KA = 1 and KB = 0 can be processed in the correction stage.

  In each of the above-described embodiments, one control unit 28 that controls each function is provided. However, the control unit 28 is not limited to one physical device, and is physically separated for each function, and each flow is The steps may be configured to be executed individually.

  The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 1 ... Injection amount measuring device 20 ... Pressure vessel 23 ... 1st pressure sensor 24 ... 2nd pressure sensor 25 ... Solenoid valve (discharge means)
27 ... Volume flow meter 28 ... Control unit 29 ... Measurement chamber 101 ... Injector (liquid injection valve)
102... Master injector (liquid injection valve, master liquid injection valve)

Claims (4)

A pressure vessel (20) forming therein a measurement chamber (29) filled with a measurement liquid;
A first pressure sensor (23) for detecting the pressure in the measurement chamber;
A discharge means (25) for discharging from the measurement chamber a volume of measurement liquid corresponding to the amount of pressure increase in the measurement chamber when the measurement liquid is ejected from the liquid injection valve (101, 102) toward the measurement chamber;
A volume flow meter (27) for measuring the volume flow rate of the measurement liquid discharged from the discharge means as an injection amount;
A control unit (28) for controlling the operation of the liquid injection valve and the discharge means;
A function check method of an injection amount measuring device comprising:
In the injection by the master liquid injection valve (102) capable of injecting the measurement liquid of the reference volume, the measurement injection amount measured as the injection amount by the volume flow meter and the first pressure sensor are detected for each of a plurality of measurement injection conditions. A first approximate linear equation calculation step (S23) in which the control unit calculates an expression of a first approximate straight line indicating the linearity of the first pressure sensor from the relationship between the pressure increase amounts,
A first linearity determination step (S24) in which the control unit determines linearity of the first pressure sensor based on whether or not a difference between the first approximate line and the measured injection amount is within an error range. When,
The function check method of the injection quantity measuring device characterized by including. The injection amount measuring device includes a second pressure sensor (24) different from the first pressure sensor for detecting the pressure in the measurement chamber,
In the injection by the master liquid injection valve,
From the relationship between the measured injection amount and the pressure increase detected by the second pressure sensor, a second approximate straight line calculated by the control unit is calculated from a second approximate straight line indicating the linearity of the second pressure sensor. Formula calculation stage (S33),
A second linearity determination step (S34) in which the controller determines the linearity of the second pressure sensor based on whether or not the difference between the second approximate line and the measured injection amount is within an error range. When,
The function check method of the injection amount measuring device according to claim 1, further comprising: In injection for each of a plurality of measurement injection conditions by the liquid injection valve (101) as a measurement target,
A correction stage for correcting the detected pressure value (W1) of one pressure sensor using a conversion factor (KA, KB) determined in advance based on the expression of the first approximate line and the expression of the second approximate line ( S42)
Based on whether or not the difference between the corrected detected pressure value (W1c) and the detected pressure value (W2) of the other pressure sensor is within an error range, the first pressure sensor or the second pressure sensor A comparison determination step (S43) for determining the function;
The function check method of the injection amount measuring device according to claim 2, further comprising: The first pressure sensor is a piezoresistive semiconductor pressure sensor,
4. The injection according to claim 2, wherein the second pressure sensor is a metal diaphragm type pressure sensor that uses an output signal when the pressure in the measurement chamber is adjusted to a set pressure. 5. Function check method of quantity measuring device.

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