RU2504680C2 - Method of ice cycle sync signal generation - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: proposed invention can be used for generation of four-stroke ICE sync signal NOCYL for ICE with uneven number of cylinders C1, C1, C3 with the help of electronic control system 7. Said NOCYL signal allows identification of preset moment at engine cylinder thermodynamic cycle. Sync signal is determined proceeding from TDC signal that identifies the position of every cylinder and signal Cg, Bn indentifying kinematics of crankshaft at fuel every ignition. Note here that both signals are generated on the basis of crankshaft position transducer 22. Proposed method comprises the steps whereat engine is operated for preset time interval with fuel ignition at engine every revolution, characteristic signal Cg, Bn is calculated with check magnitude at first second revolutions, sync signal NOCYL is re-initiated if sync signal is misphased.

EFFECT: decreased emission of contaminants.

4 cl, 3 dwg

Description

The present invention relates to a method for generating a synchronization signal characterizing the flow of a four-stroke internal combustion engine such as a multi-cylinder engine, in which the expansion phases in each cylinder occur at different angular positions of the rotational movement of the crankshaft, as in the case of four-stroke engines with an odd number of cylinders.

In particular, the invention relates to a method of generating a signal that allows to detect a predetermined moment of the cycle, such as the transition through the top dead center at the inlet or through the bottom dead center on the inlet.

Engine performance as well as emission control are associated with various control processes that regulate engine operation. These processes, in particular fuel injection or ignition, require an accurate knowledge of the thermodynamic cycle taking place in the engine cylinders.

Document FR 2441829 proposes a means for obtaining information on the thermodynamic cycle of cylinders by notching on a control element fixedly connected to the crankshaft, angular position zones corresponding to a certain stroke phase of various pistons. The control element is a disk containing marks located along its circumference, such as teeth of different lengths. The stationary receiving organ detects these marks and generates electrical impulses, allowing you to create a signal that marks the transition of a particular piston to the top dead center position.

However, such a notch device is not enough. Indeed, in a four-stroke internal combustion engine, the crankshaft performs two full turns (or passes an angle of 720 °) before this piston is in the same working position in the engine cycle. Therefore, based on only one observation of the rotation of the control element fixedly connected to the crankshaft, it is impossible to obtain information on each cylinder, avoiding the uncertainty of two clock cycles in the cycle (since the notch of the top dead center refers to both the intake phase and the expansion phase).

An exact determination of the position of each cylinder in the cycle cannot be deduced only on the basis of observation of the position of the crankshaft; therefore, additional information needs to be obtained to find out if the cylinder is in the first or second half of the engine cycle (intake phase and then compression during the first crankshaft revolution shaft, expansion phase, then release during the second revolution).

To obtain such additional information, it is known that auxiliary marks are applied on a transmission disk, which rotates twice as slow as a crankshaft. To do this, this transmission disk can be placed on the cam shaft or on any other shaft, which is driven through a gearbox with a gear ratio of 1/2 from the crankshaft.

The combination of signals from the crankshaft sensor and the cam shaft sensor allows the system to accurately detect top dead center in the intake phase of the control cylinder.

However, such angular notch systems that simultaneously use the crankshaft sensor and the cam shaft sensor are rather cumbersome, expensive, and difficult to install.

To address these shortcomings, FR 2749885 proposes a simple and effective notch method that does not require any special position sensor other than a sensor that measures the angular position of the crankshaft.

This method uses a synchronization signal, which is generated based on the combustion conditions in each of the cylinders of a four-stroke four-cylinder engine and the data transmitted by the crankshaft sensor.

For this, at least one factor controlling the combustion in a given control cylinder is changed in such a way as to cause a controlled change in combustion. This change in combustion in the control cylinder is detected due to the value of Cg, which is set based on information received from the engine crankshaft position sensor, which allows synchronizing transitions to the top dead center of the engine cylinders at the inlet with the signal of the top dead center of the crankshaft sensor.

However, this invention involves the deterioration of fuel combustion in the engine, which impairs its operation and leads to an increase in the emission of pollutants.

The present invention is intended to eliminate the disadvantages of known notch systems in the case of a four-stroke engine containing an odd number of cylinders, and to propose an improved notch method that does not require any other specific position sensor, except for a sensor that serves to determine the angular position of the crankshaft, and does not impair engine operation.

In this regard, the present invention is to provide a method for obtaining a synchronization signal of a four-stroke internal combustion engine with an odd number of cylinders using an electronic control system. According to the invention, a synchronization signal, allowing to detect a predetermined moment in the thermodynamic cycle of each of the engine cylinders, is determined on the basis of a signal indicating the specific position of each cylinder and a signal representing a value characterizing the kinematics of the crankshaft for each ignition, both of which generate based on the data of the crankshaft position sensor, the method comprising the following steps, in which

- ensure the operation of the engine during this period with the ignition of fuel in the cylinders at each revolution so as to obtain a systematic ignition of the injected fuel,

- calculate the characteristic signal

- compare the characteristic signal with the control value,

- reinitialize the synchronization signal if the comparative analysis shows poor phasing of the synchronization signal.

According to other features of the invention, the characteristic signal of the cylinder during the first turn of the cycle can be compared with the characteristic signal of the cylinder during the second turn of the cycle to find out the phase of the first turn, and re-initialize the synchronization signal if the phasing turned out to be erroneous.

The characteristic signal may be a characteristic of the torque generated by the gas or a harmonic characteristic of the duration of the tooth.

Other features and advantages of the present invention will be more apparent from the following description with reference to the accompanying drawings, in which:

figure 1 - diagram of an engine control device that implements the method in accordance with the present invention;

figure 2 - diagram of the steps of the injection process using a synchronization signal in accordance with the present invention;

figure 3 - phasing of the synchronization signal NOCYL in accordance with the present invention.

Regardless of the embodiment of the invention, identical or similar in their functions elements are indicated in the description text by the same positions.

The figures show an engine control system that implements a method for generating a synchronization signal and is an object of the present invention. The figures show only those parts that are necessary for the disclosure of the invention. In addition, in this example, the synchronization signal allows you to adjust the injection system, but the use of the signal is not limited to this, and the synchronization signal can be used to control other elements or processes in the engine.

The four-stroke internal combustion engine 1 for a vehicle contains three cylinders (C1, C2, C3), each of which contains an electronically controlled multi-point type fuel injection device, thanks to which each cylinder receives fuel through a special electric injector 5.

The opening of each electric injector 5 is controlled by an electronic engine control system 7, which adjusts the amount of fuel injected and the moment of injection (Inj) in a cycle depending on engine operating conditions, in order to precisely control the composition of the air-fuel combustible mixture entering the cylinders according to a predetermined predetermined value .

Classically, the electronic engine control system 7 comprises a microprocessor (CPU), random access memory (RAM), read-only memory (ROM), as well as analog-to-digital converters (A / D) and various input and output interfaces.

The microprocessor contains electronic circuits and corresponding programs (10, 222, 223, 224) for processing signals from the corresponding sensors, for determining engine conditions and performing predetermined operations in order to generate control signals, in particular for injectors, in order to create optimal conditions combustion in engine cylinders.

In particular, the electronic engine control system 7 is intended for such a fuel injection control in which each injector 5 is separately actuated so that the fuel injection is completed before the corresponding intake valve or respective intake valves are opened.

Among the input signals of the microprocessor, in particular, signals coming from the crankshaft sensor 22 are featured. This sensor 22, for example, a sensor with magnetic resistance, is fixedly mounted on the engine housing and is located in front of the measuring ring 12, fixedly connected to the flywheel, mounted on the end of the crankshaft. This ring 12 contains on the periphery a consecutive row of identical teeth and grooves, with the exception of one tooth, which is removed to obtain an absolute mark, allowing to determine the moment of transition to the top dead center of this control cylinder, in this case cylinder C1.

The sensor 22 generates a signal Dn corresponding to the passage of the teeth of the ring 12, which after processing by the processing device 10 allows to generate a TDC signal (top dead center) every 120 ° of crankshaft rotation, which allows one to detect transitions to the top dead center of the C1 cylinders in turn (0 ° mark ), then C2 (120 ° mark) and finally C3 (240 ° mark) if the engine cycle order corresponds to C1-C3-C2, as in this example.

It should be noted that for this type of four-stroke three-cylinder engine and, in general, for all four-stroke engines with an odd number of cylinders, the cylinders, in this case C1, C2 and C3, go to the top dead center TDC position in different angular positions.

The device 10 of the signal processing Dn, issued by the sensor 22, also allows you to measure the duration of the teeth of the ring 12, as well as to determine the speed and instantaneous speed of rotation N of the engine.

In addition, the signal Dn is processed by the device 10 to create a signal (Cg, Bn), which reflects a value characterizing the kinematics of the crankshaft. For example, this value may determine the characteristic of the estimated torque generated by the gas at each ignition.

The value of the signal Cg for each of the ignition of the gas mixture in the engine cylinders is obtained, in particular, on the basis of the analysis of the signal Dn, issued by a stationary sensor 22, controlling the gear wheel 12, fixedly connected to the crankshaft.

The signal is not used directly, for example, considering the instantaneous rotation speed, since the presence of noise during measurement or the presence of a defect in the teeth can lead to significant errors associated with inaccuracies in the signal and reduce the reliability of the method. Therefore, harmonic decomposition analysis eliminates these shortcomings.

A method for producing such a Cg signal is described, in particular, in patents EP 0532420 or WO 9829718, in which the signal Cg characterizes the torque generated by the gas. Typically, an estimate of the average gas torque generated by at least one ignition in the cylinder "u" of the engine containing p cylinders is obtained using a relationship of the following form:

,

,

Where:

[C _{gaz, 0} ] is the average gas torque generated by at least one ignition in the cylinder and during the combustion cycle,

β _{k, I} is a function of Δt _k and / or ω _k, respectively, of the duration and speed of the label Dk in front of the sensor,

α _{k, I} is the weight coefficient of the duration associated with the label Dk, depending on at least one parameter of the engine,

α _{0, I} is a variable depending on at least one parameter of the engine,

δ _i - weight coefficient,

i is the index for counting linear combinations of functions,

qu and ru respectively denote the number of the first mark and the number of the last mark detected by the position sensor while burning in cylinder u, or the virtual last mark created on the basis of the sensor signal defining the angular window for analyzing engine torque associated with burning in cylinder u.

Using specific values with some coefficients of the aforementioned Cg ratio, other values characterizing the kinematics of the crankshaft, such as harmonic components characterizing the speed or duration of the passage of the gear teeth, can be determined. The duration of the passage of the tooth is the duration measured between the two teeth of the control element.

For example, using the characteristic average estimated gas torque for a four-stroke engine with three cylinders C1, C2 and C3, where the burning time in cylinder C1 is between 0 ° and 180 °, torque is estimated by observing a rotation speed between 0 and 240 ° or in the corner window, as a rule, including the intervals 0-180 ° of the combustion phase in cylinder C1.

According to the same principle, the combustion time associated with cylinder C3 is between 240 ° and 420 °, and observation will be made in an angular interval comprised between 240 ° and 480 °.

For cylinder C2, the burning time is between 480 ° and 660 °, and the observation interval of the engine mode will be around 480 ° and 720 °.

In this case, the method of obtaining the synchronization signal is carried out according to the following principle.

A serif of a predetermined moment during the engine cycle, which is used to phase the injection into each cylinder and which in the example is a transition through the top dead center of the inlet, or any other moment that can serve as a mark, is made based on the NOCYL synchronization signal synchronized with TDC signal, marking the transition to the top dead center of each cylinder, in the circuit 224.

Several types of NOCYL synchronization signal can be used, which separately or in combination with the signal from the TDC number counter of cylinders passing in front of the position sensor allows determining the phase of the combustion cycle for each cylinder.

In this example, the NOCYL signal, shown in Fig. 3, does not require comparison with other signals and allows you to get all the serifs of predetermined moments in the course of the engine cycle used for phasing injection or ignition in each of the cylinders for all engine cylinders.

Indeed, the NOCYL signal determines the transition to the top dead center on the inlet and the transition to the top dead center when expanding for all cylinders at the moment the value changes. In this case, one signal is sufficient for synchronization of all actuators for engine control.

The TDC signal shows each transition to the top dead center of the engine cylinders due to the generation of a rising edge or falling edge. The NOCYL signal is arbitrarily initialized to 0 upon the first detection of a transition to the top dead center of the control cylinder (in this example C1), which is arbitrarily taken as the top dead center of the inlet, then it is incremented. The NOCYL signal is constructed by incrementing the counter modulo 6 at each passage through the top dead center of the TDC signal.

Thus, when the NOCYL signal goes to 0 or 3, this means that the TDC of cylinder C1 is detected respectively in the inlet or expansion phase.

When the NOCYL signal goes into the value 1 or 4, this means that the TDC of cylinder C2 is detected respectively in the intake or expansion phase.

When the NOCYL signal changes to 2 or 5, this means that the TDC of cylinder C3 is detected respectively in the intake or expansion phase.

Regardless of the implementation of the NOCYL signal, it provides a single reference point for all engine cycles, which allows the phasing system 222 to synchronize any engine control process (ignition, injection, actuator control, etc.).

Taking into account the arbitrary choice used during the initialization of the NOCYL signal, two cases can be indicated: either the NOCYL signal is phased correctly, while the control top dead center was used to initialize the signal really corresponding to the top inlet dead center for control cylinder C1, or the NOCYL signal is phased incorrect, and in this case, the control top dead center corresponds to the top dead center of the expansion for the control cylinder C1.

In the first embodiment of the invention, when the engine is, for example, in the starting phase, estimating the moment Cg using the evaluation function described above makes it possible to check whether synchronization has been correctly performed. Indeed, if the injection and ignition are phased incorrectly, the engine cannot produce torque, since combustion occurs during the intake. Processing unit 223 compares the estimated value of Cg with the reference or setpoint Cc classically obtained by the engine control device during startup to evaluate whether phasing is correct. At the same time, the following condition is checked:

,

,

where ξ is a positive value of the torque, which can be constant or mapped depending on the regulating parameters of the engine, in order to ensure the reliability of the criterion E1 by limiting the consideration of signal noise.

If this condition is not satisfied, the phasing is incorrect, in which case it is considered that the detected top dead center was the top dead center of the extension, and the NOCYL signal is reinitialized in the circuit 224 by the signal Init of the signal processing circuit 223 of the Cg signal. Since phasing is now correct, condition E1 must be satisfied. If it does not, then there is a malfunction in the injection system or in the engine.

However, this method is not necessarily compatible with the so-called "lost spark" strategy, which is usually applied during engine start-up, which consists of ignition in the cylinders at each engine revolution (top inlet and expansion top dead center) during the start-up phase gasoline engine, as opposed to sequential ignition with one ignition per thermodynamic cycle, in order to make sure that combustion will occur and thus avoid injecting fuel that will not be burned, and at the same time It is able to provide a quick start. Thus, until the thermodynamic cycle is determined, the engine is ignited in the “lost spark” mode until the sequential ignition is restored.

A second embodiment of the invention allows operation in the event of a start with a lost spark.

In this embodiment, until synchronization is achieved, the ignition of the engine is controlled in the aforementioned “lost spark” mode to enable the engine to start and operate even when the phasing of the engine is not identified.

The torque is evaluated by observing the acyclicity of the instantaneous speeds or the duration of the rotation of the engine crankshaft in an angular interval that is directly related to the expected phasing of the engine and theoretically covers the combustion phases of three cylinders.

In this example, the burning time in the cylinder C1 is between 0 ° and 180 °, the moment is estimated by observing the rotation speed between 0 ° and 240 ° or in the corner window, as a rule, covering the intervals 0-180 ° of the burning phase in the cylinder C1.

According to the same principle, the corresponding burning time in cylinder C3 is between 240 ° and 420 °, acyclicity is observed in the angular range from 240 ° to 480 °.

For cylinder C2, the burning time is between 480 ° and 660 °, while the range of observation of the engine mode is between about 480 ° and 720 °.

If the phasing of the combustion sequences is not identified, the estimated torque Cg generated by combustion in cylinder C1 is observed one revolution later, that is, between 360 ° and 600 ° instead of the interval 0-240 °.

In this case, it is not combustion observed in cylinder C1, but the end of combustion in cylinder C3 and the beginning of combustion in cylinder C2, and the estimated torque Cg in this example is negative for these combustion times for cylinders C2 and C3.

Thus, if the timing is incorrect, the value of the estimated torque Cg is negative, not positive. Therefore, if Cg≥0 (E2), the synchronization is normal, but if Cg≤0, the synchronization is bad, in which case the NOCYL signal is reinitialized, as in the first embodiment.

Versions of the second embodiment of the invention may also be provided.

The first version of the second embodiment is to evaluate the torque of the gas Cg at all engine speeds. The estimated torque Cg1_1 thus obtained at the first revolution for cylinder C1 is recorded in memory and compared with a new observation of the torque Cg1_2 for cylinder C1 at the next revolution.

A comparison of the torques Cg1_1 and Cg1_2 allows you to determine the normal synchronization by the following condition:

Cg1_1> Cg1_2 (E4), if revolution 1 corresponds to cylinder C1 during expansion and revolution 2 corresponds to inlet.

Cg1_1 <Cg1_2 (E5), if revolution 2 corresponds to cylinder C1 during expansion and revolution 1 corresponds to inlet.

In each of these two cases, synchronization can be performed in accordance with the result of the comparison.

The second version consists in comparing the value of the estimated torque Cg for a given cylinder with a given value of the torque Cc, according to the following ratio:

Cg> SS-Delta (Speed, SS) (E6), if the synchronization is correct.

Cg <Cc-Delta (Speed, Cc) (E7) if the timing is incorrect.

Indeed, if the synchronization is incorrect, the NOCYL signal does not correspond to the thermodynamic cycle of each cylinder, in which case the value of the estimated torque Cg is much less than the set value Cc and vice versa.

The Delta shift is a torque value that can be constant or obtained from mapping, depending on the speed and / or torque of the engine, and which allows you to fix the threshold necessary for comparison to eliminate any possibility of erroneous synchronization associated with noise in the signals.

The reliability of the basic methods and versions of the first and second embodiments can be improved by limiting the errors associated with interference or noise of the signals, for example, by summing the estimates of the torque Cg.

In this case, the ratio (E1) from the first embodiment takes the following form:

Relations (E2) and (E3) of the basic method of the second embodiment take the form:

если синхронизация является правильной,

if the synchronization is correct,

если синхронизация является неправильной.

if the synchronization is wrong.

The ratio (E4) and (E5) of the first version of the second embodiment of the invention take the form:

The ratio (E6) and (E7) of the second version of the second embodiment of the invention take the form:

For each of the two embodiments, the error can be limited by filtering, for example, using first or second order filters or any other filter that allows you to filter out noise in measurements and estimates, due to which the result of comparisons becomes more reliable. An example is a discrete filter of the first order F, defined as:

F _n (X _n ) = αX _n + (1_α) F _n-1 for 0 <α <1

In this case, the ratio (E1) of the first embodiment takes the form:

F (Cg) ≥F (Cc-ξ)

Relations (E2) and (E3) of the basic method of the second embodiment take the form:

F (Cg) ≥0

F (Cg) ≤0

The ratio (E4) and (E5) of the first version of the second embodiment of the invention take the form:

F (Cg1_1) ≥F (Cg1_2)

F (Cg1_1) ≤F (Cg1_2)

Relations (E6) and (E7) of the second version of the second embodiment of the invention take the form:

F (Cg) ≥F (Cc-Delta (N, Cc))

F (Cg) ≤F (Cc-Delta (N, Cc))

As mentioned above, you can use the characteristic value, characterizing the kinematics of the crankshaft, different from the moment. Thus, in the third embodiment of the invention, harmonic analysis is used, characterizing either the duration of the tooth or the instantaneous speed of rotation of the crankshaft.

Thus, this embodiment consists in considering the harmonic component of order n of the rotation speed, or preferably the duration of the tooth, established on the basis of the signal Dn. In this case, the harmonic component Bn is calculated using the harmonic cosine function, but the method can be adapted for any other harmonic function, for example, the trapezoid function or another, more complex function. This component Bn is a simplified characteristic established based on the above estimated torque ratio (Cg) using the respective factors.

For this example, the harmonic component of the tooth duration can be set using the following relationship:

между гармоническими амплитудами, вычисленными для двух возможных фазирований рассматриваемого цилиндра, вычисленных для верхней мертвой точки, при воспламенении, и для верхней мертвой точке, при выпуске, позволяет установить три случая.Difference calculation

Between the harmonic amplitudes calculated for the two possible phasing of the cylinder in question, calculated for top dead center, when ignited, and for top dead center, when released, three cases can be established.

больше максимального значения, значит, двигатель фазирован правильно.If

greater than the maximum value, then the engine is phased correctly.

меньше минимального значения, значит, двигатель фазирован неправильно.Ate

less than the minimum value, which means that the engine is phased incorrectly.

находится между этими двумя пороговыми значениями, существует неопределенность, и вычисление необходимо повторить.If

is between these two thresholds, there is uncertainty, and the calculation must be repeated.

In each of these two cases, synchronization can be carried out depending on the result of the comparison, as in previous embodiments.

This embodiment is reliable for defects in the control element, since it compares two values that are potentially equally displaced due to a defect in the control element, while in the calculations of Bn at two TDC cylinders, the durations measured at the same angular angles are taken as initial data sections of the control element of the ring. Indeed, the harmonic component established at the first revolution will be decomposed into the sum of the harmonic component characterizing the thermodynamic cycle during the first revolution and the harmonic component characterizing the defects of the control element. The harmonic component installed on the second revolution will be decomposed into the sum of the harmonic component characterizing the thermodynamic cycle during the second revolution and the harmonic component characterizing the defects of the control element, which is the same as on the first revolution. Therefore, a comparison of the harmonic component installed on the first revolution and the harmonic component installed on the second revolution will eliminate the harmonic component characterizing the defects of the control element.

Regardless of the detection option being implemented, in case of poor synchronization, the NOCYL signal is reinitialized by changing the synchronization assumption (synchronization offset by one revolution). This reinitialization can be performed at the TDC of the control cylinder or at any TDC of any cylinder. In this case, the synchronization must again be confirmed using the method according to one of the above embodiments, until normal engine operation in sequential ignition mode is established.

Preferably, the invention allows synchronization of the thermodynamic cycle of each cylinder, without changing the parameters of the engine and without affecting the operation of the engine.

Claims (4)

1. A method of obtaining a synchronization signal (NOCYL) for a four-stroke internal combustion engine with an odd number of cylinders (C1, C2, C3) using an electronic control system (7), characterized in that the synchronization signal (NOCYL) used to detect a given moment in the thermodynamic cycle of each of the engine cylinders is determined based on the top dead center (TDC) signal, which indicates the specific position of each cylinder, and the signal (Cg, Bn), which displays the value characterizing the kinematics of the crankshaft at each ignition of the fuel, while both signals are formed on the basis of the sensor (22) position of the crankshaft, and the method includes the steps of
ensure the operation of the engine for a predetermined period with the ignition of fuel in the cylinders at each revolution in order to systematically ignite the injected fuel,
calculate the characteristic signal (Cg, Bn),
comparing the characteristic signal (Cg, Bn) with a control value,
re-initialize the synchronization signal (NOCYL), if a comparative analysis shows that the synchronization signal is incorrectly phased, while
characteristic signal (Cg, Bn) of the cylinder during the first revolution in the cycle (Cg1_1,

) are compared with the characteristic cylinder signal during the second revolution in the cycle (Cg1_2,

) to find out the phase of the first revolution, and re-initialize the synchronization signal (NOCYL) if the phasing turned out to be erroneous. 2. The method of obtaining a synchronization signal (NOCYL) according to claim 1, in which the characteristic signal (Cg) is a characteristic of the torque generated by the gas. 3. The method for obtaining a synchronization signal (NOCYL) according to claim 2, in which the torque generated by the gas during at least one combustion in the cylinder u of the engine containing p cylinders is estimated using the following relation:

where [C _{gaz, 0} ] _u is the average gas moment produced by at least one combustion in cylinder u during the combustion cycle,
β _{k, i} is the function Δt _k and / or ω _k, respectively, of the duration and speed of the label Dk in front of the sensor,
α _{k, i} is the weight coefficient for the duration associated with the label Dk, depending on at least one operating parameter of the engine,
α _{0, i} is a variable depending on at least one operating parameter of the engine,
δ _i - weight coefficient,
i - reference index of linear combinations of functions,
q _u and r _u are, respectively, the number of the first mark and the number of the last mark detected by the position sensor during fuel combustion in the cylinder u, or the virtual last mark formed on the basis of the sensor signal and defining an angular window for analyzing engine torque associated with fuel combustion in cylinder u. 4. The method of obtaining a synchronization signal (NOCYL) according to claim 1, in which the characteristic signal (Bn) is a harmonic representation of the duration of the tooth.

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