JP2004239095A - Control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for improving fuel-economy by accurately and appropriately preventing an engine from running at idle in starting up an engine. <P>SOLUTION: The control device is intended for a vehicle provided with a generator for generating power on the basis of rotation of an internal combustion engine, and a secondary battery which is charged on the basis of power supplied from the generator. The control device includes a control means for controlling a charging capacity to the secondary battery. The control means is constituted of ECU (electronics control unit) and a DC/DC converter. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for a vehicle, and more particularly to a control technique for preventing a blow-up when starting an engine.
[0002]
[Prior art]
Conventionally, while automatically stopping the engine under predetermined stop conditions, for example, when an automobile stops at an intersection, etc., the engine is restarted under predetermined restart conditions, for example, when an accelerator pedal is depressed. There has been proposed an automatic stop and start device capable of saving fuel consumption and reducing exhaust emissions.
[0003]
Here, the hydraulic pump of a normal transmission is driven by the engine, and when the engine stops, the hydraulic pump driven by the engine also stops, so that the hydraulic pressure of the transmission decreases. As a result, when the engine is restarted at the time of restart, the hydraulic pump also operates, but the hydraulic pressure rise of the transmission is delayed, and the engine is blown up due to the delay of engagement of the clutch provided between the transmission and the output shaft of the engine. There was a problem that (air blow) occurred.
[0004]
To solve this problem, a technique has been proposed in which, for example, a motor generator (power generation / electric means) functions as a generator to consume engine drive torque and prevent blow-up (Patent Document 1).
[0005]
[Patent Document 1]
JP-A-09-71138
[Problems to be solved by the invention]
In the prior arts such as Patent Document 1, in order to prevent blow-up, a current flowing through a stator winding of a motor generator is adjusted to change a magnetic flux, thereby generating electric power, and consequently, torque consumption (engine torque consumption). Among them, a framework based on excitation control, which controls the torque consumed by the motor generator, is adopted.
[0007]
However, in general, excitation control does not have a high response characteristic, and it has not always been easy to accurately and appropriately prevent blow-up under the above framework.
[0008]
Accordingly, it is an object of the present invention to provide a technique capable of accurately and appropriately preventing a blow-up when starting an engine and further improving fuel efficiency.
[0009]
[Means for Solving the Problems]
A control device for a vehicle according to the present invention is directed to a vehicle including a power generation unit that generates power based on the rotation of an internal combustion engine, and a secondary battery unit that is charged based on electric power supplied from the power generation unit. In order to suppress an increase in the number of revolutions of the engine, a control means for controlling the amount of charge to the secondary battery means is provided. In this case, it is preferable that the control means includes an ECU (Electronic Control Unit) and a DC / DC converter. According to this configuration, it is possible to control the amount of charge, and thus the torque consumption, at an appropriate timing, and as a result, it is possible to accurately suppress an increase in the engine speed and prevent a blow-up.
[0010]
Preferably, the control means determines the amount of charge to the secondary battery means based on an accelerator opening. According to such a configuration, the degree of suppression can be changed according to the driver's intention which is reflected on the amount of depression of the accelerator, and the blow-up prevention function can be flexibly realized.
[0011]
Preferably, the control means controls the amount of charge to the secondary battery means on condition that the rotation speed of the internal combustion engine is within a predetermined range. According to this configuration, when the rotational speed of the internal combustion engine is out of the predetermined range, it is possible to smoothly start and advance without a sense of incongruity for the driver based on the normal engine control without running out of power. It becomes.
[0012]
In this case, it is preferable that the control unit changes the predetermined range based on an accelerator opening. According to such a configuration, the degree of suppression can be changed according to the driver's intention which is reflected on the amount of depression of the accelerator, and the blow-up prevention function can be flexibly realized.
[0013]
Preferably, the control unit controls the amount of charge to the secondary battery unit within an upper limit time set for the time for controlling the amount of charge. According to such a configuration, an increase in the engine speed can be suppressed more than necessary, and a situation in which starting is delayed can be prevented.
[0014]
Preferably, the secondary battery means includes a first secondary battery charged based on electric power from a power generating means, and a second secondary battery charged based on electric power from the first secondary battery. And at least a battery, wherein the control means controls a charge amount charged from the first secondary battery to the second secondary battery.
[0015]
A vehicle control method according to the present invention includes a power generation step of generating power based on the rotation of an internal combustion engine, a charging step of charging a secondary battery based on power generated in the power generation step, and an increase in the rotation speed of the internal combustion engine. And a control step of controlling the amount of charge to the secondary battery in order to suppress power consumption.
[0016]
The vehicle control method of the present invention can be implemented by a computer, and a computer program for that can be installed or loaded on the computer through various media such as a CD-ROM, a magnetic disk, a semiconductor memory, and a communication network. it can.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a system configuration diagram of a vehicle internal combustion engine to which the above-described invention is applied and a control device thereof. Here, a gasoline engine (hereinafter, referred to as "engine") 2 is used as an internal combustion engine.
[0018]
The output of the engine 2 is output from a crankshaft (corresponding to a drive shaft) 2a of the engine 2 via a torque converter 4 and an automatic transmission (automatic transmission: hereinafter referred to as "A / T") 6 on the output shaft 6a side. And finally transmitted to the wheels. Further, separately from such a driving force transmission system from the engine 2 to the wheels, the output of the engine 2 is transmitted to the belt 14 via the pulley 10 connected to the crankshaft 2a. Then, another pulley 16 is rotated by the output transmitted by the belt 14.
[0019]
An alternator (hereinafter, referred to as “ALT”) 26 is linked to the belt 14 by a pulley 16. The ALT 26 converts the rotational force transmitted from the engine 2 through the pulley 16 into electric energy, and supplies electric power to the auxiliary equipment 22 when the vehicle is running, for example. Examples of the accessories 22 include a compressor for an air conditioner, a power steering pump, a water pump for cooling an engine, and the like. Although FIG. 1 shows one accessory 22, one or more of an air conditioner compressor, a power steering pump, an engine cooling water pump, and the like actually exist.
[0020]
Further, the ALT 26 charges the battery 30 via the rectifier 27 and the regulator 28 and further charges the battery 34 via the DC / DC converter 32 with electric energy. The battery 30 is, for example, a 12V lead battery, and the battery 34 is, for example, a 12V lithium battery.
[0021]
The electric energy charged in the battery 30 is supplied to the starter 36, for example, at the time of an initial start (engine start by an ignition key), and is used to start the engine 2 by rotating a ring gear. On the other hand, the electric energy charged in the battery 34 is supplied to the starter 36, for example, when restarting from the engine automatic stop state, and is similarly used to start the engine 2 by rotating the ring gear. When the batteries are properly used in this way, it is desirable to control the battery 30 (lead battery) to be charged with priority over the battery 34 (lithium battery).
[0022]
The A / T 6 is provided with an electric hydraulic pump 38 supplied with electric power from the battery 30 or 34, and supplies hydraulic oil to a hydraulic control unit inside the A / T 6. This hydraulic oil adjusts the operating states of the clutch, brake and one-way clutch in the A / T 6 by a control valve in the hydraulic control unit, and switches the shift state as necessary.
[0023]
The control of the ALT 26 and the starter 36 and the control of the amount of stored power for the batteries 30 and 34 (not shown) are executed by an eco-run ECU (electronics control unit) 40 and an engine ECU 48. Also, the drive on / off of the auxiliary equipments 22 except the water pump, the drive control of the electric hydraulic pump 38, the shift control of the A / T 6, the fuel injection control by the fuel injection valve (intake port injection type or the in-cylinder injection type) 42, the electric motor The control of the opening of the throttle valve 46 by the control 44 and other engine controls are executed by the engine ECU 48. In addition, since the brake ECU 50 is provided, automatic control of the brake of each wheel is also performed.
[0024]
The eco-run ECU 40 detects the number of revolutions of the rotating shaft of the ALT 26 from a revolution number sensor incorporated in the ALT 26, the presence or absence of activation of the eco-run system by the driver from the eco-run switch, and other data. Further, the engine ECU 48 is provided with an engine cooling water temperature from a water temperature sensor, an accelerator pedal depression state from an idle switch, an accelerator opening degree from an accelerator opening sensor, a steering angle from a steering angle sensor, a vehicle speed from a vehicle speed sensor, and a throttle opening sensor. , The throttle position from the shift position sensor, the engine speed from the engine speed sensor, the presence / absence of on / off operation from the air conditioner switch, and other data for engine control and the like. The brake ECU 50 also detects the presence or absence of depression of a brake pedal from a brake switch and other data for braking control and the like.
[0025]
Each electronic control unit such as the eco-run ECU 40 includes a CPU (processor), a ROM, a RAM (which may include a backup RAM for storing data to be stored when the engine 2 is stopped), an input interface, an output interface, and the like. Be composed. The CPU is capable of accessing a ROM or the like via an internal bus, executes various control processes based on predetermined data stored in the ROM, a control algorithm, or the like, and executes a calculation result or an input result via an input interface. A process for storing data and the like input from the sensor in the RAM is executed. The ECU 40, 48, 50, and the like can exchange data with each other on these calculation results, data, and the like, and exchange data as necessary to execute control in conjunction with each other. Is possible.
[0026]
The eco-run ECU 40 automatically instructs the engine ECU 48 to cut off the fuel supply when the vehicle is under a predetermined condition, for example, when the vehicle is temporarily stopped at a traffic light or the like, as in the related art. When the vehicle is under predetermined conditions such as when the vehicle starts again, power is supplied from the battery 30 or 34 to the starter 36, and the engine ECU 48 is instructed to restart fuel supply to restart the engine 2. It is configured to execute automatic stop / start control.
[0027]
Here, in the automatic stop / start control, the D eco-run for performing the automatic stop / start control of the engine when in the D or NP position, and the automatic stop / start control for the engine only in the NP position, and in other positions, There are two types of N-eco-runs that do not perform automatic stop / start control of the engine.
[0028]
The automatic stop conditions include, for example, 1) when the brake pedal is depressed, the brake master pressure exceeds a predetermined threshold value due to the depression force, and a predetermined time has elapsed in that state; 2) Various conditions are considered according to the design, such as an operation of changing the shift position from the driving position to the non-driving position, or an operation of putting the parking brake into an operating state and a predetermined time set in that state has elapsed. be able to.
[0029]
The automatic start conditions include, for example, 1) that the shift position is in the non-drive position and that there is a start request by key operation; 2) that the shift position is in the drive position (D eco-run is being executed); 3) The shift request position is in the drive position (D eco-run is being executed), and 200 ms has elapsed with the idle switch flag indicating the OFF state. Various conditions can be considered accordingly.
[0030]
The brake start request flag indicates that the brake switch indicates that the brake pedal is not depressed, or that the brake master pressure is smaller than a predetermined threshold value (for example, 0.4 MPa), or that the decreasing change width of the brake master pressure is a predetermined threshold value ( For example, a flag indicating the ON state when either of the conditions is equal to or greater than 0.06 MPa), and indicating the OFF state otherwise. The idle switch flag indicates an ON state when the idle switch indicates that the accelerator pedal is fully closed (when an output request is not issued to the engine 2), and indicates an OFF state otherwise.
[0031]
As described above, the configuration and operation of the engine 2 and each ECU are basically the same as the conventional configuration and operation. However, the eco-run ECU 40 of the present embodiment controls the amount of torque charged by the ALT 26 by controlling the amount of charge to the battery 34 after the start of the engine 2, thereby suppressing an increase in the rotational speed of the internal combustion engine. It is different from the conventional configuration in that it has a function of preventing blow-up.
[0032]
Hereinafter, such a blow-up prevention function will be described.
[0033]
First, the principle by which the amount of torque consumed by the ALT 26 can be controlled by controlling the amount of charge to the battery 34 will be described. A predetermined electromotive force is generated by the ALT 26 based on the rotation of the engine 2, and the battery 34 is charged via the DC / DC converter 32 based on the electromotive force. In this case, the amount of charge to the battery 34 can be controlled by adjusting the output voltage of the DC / DC converter 32. When the amount of charge to the battery 34 increases or decreases, that is, when the electric energy used to charge the battery 34 increases or decreases, the increase or decrease in the electric energy is compensated for by the increase or decrease in the amount of power generated by the ALT 26. 28 tries to keep the output voltage constant, so that the current output by the ALT 26 increases or decreases. Since the current output from the ALT 26 generates a magnetic field in a direction to stop the rotation of the ALT 26 inside, the ALT 26 becomes difficult to rotate as the current increases, and as a result, the driving torque of the engine 2 is further consumed. Become.
[0034]
Next, a process executed by the eco-run ECU 40 to realize the blow-up prevention function will be described based on the flowchart shown in FIG.
[0035]
The eco-run ECU 40 executes the following blow-up prevention processing under the control of the CPU based on the control algorithm recorded in the ROM when the engine is started. In addition, each step (including a partial process without a reference numeral) can be arbitrarily changed in order or executed in parallel within a range that does not cause inconsistency in the processing content.
[0036]
First, the eco-run ECU 40 determines whether or not the engine 2 has started to be started (S100). If it is determined that the process has started, the process proceeds to S101.
[0037]
Next, the eco-run ECU 40 determines whether the first explosion of the engine 2 has been performed (S101). When it is determined that the first explosion has been performed, the process proceeds to S102.
[0038]
Next, the eco-run ECU 40 determines whether or not the rotation speed of the engine 2 is equal to or higher than a predetermined value (S102). If it is determined that the value is equal to or more than the predetermined value, the process proceeds to S103.
[0039]
Next, the eco-run ECU 40 initializes a counter for storing the execution time of the charge amount control process, and sets an upper limit value of the execution time (S103).
[0040]
The upper limit value of the execution time is set in order to prevent an increase in the engine speed over an unnecessarily long time and to prevent a smooth start from being hindered. The specific value can be determined according to the design, but may be, for example, about several hundred msec.
[0041]
Next, the eco-run ECU 40 starts the charge amount control process (S104 to S112).
First, referring to the correspondence between the accelerator opening and the charge amount stored in the ROM, the amount of charge to the battery 34 (electric energy supplied to the battery 34) is determined based on the accelerator opening at that time (S104). ).
[0042]
As shown in FIG. 3A, the correspondence between the accelerator opening and the charge amount is qualitatively such that the larger the accelerator opening, the smaller the charge amount. When the accelerator opening is large, that is, when the accelerator is depressed by a large amount, it can be considered that the driver intends to start quickly, so that it takes longer than necessary for the engine speed to reach the idling speed. Is not preferable. For this reason, in the present embodiment, the above-described correspondence is adopted, and as the accelerator opening increases, the amount of charge is reduced to suppress the degree of suppression of the number of revolutions, thereby shortening the time required to reach the idling number of revolutions. I have.
[0043]
The amount of charge corresponding to the accelerator opening is a driving torque of the engine 2 generated according to the accelerator opening, a torque consumed by charging the battery 34, and a rate of increase in the engine speed based on the torque consumption. The degree of suppression of the (rising speed) is measured in advance based on a test or the like, and based on the measured value, the engine speed is determined so as to approach the idling speed (target speed) without overshooting. be able to.
[0044]
Next, the eco-run ECU 40 determines the state of charge of the battery 30 (S105).
[0045]
When it is determined that the battery 30 is not in the fully charged state, a correction is made to subtract the electric energy necessary for charging the battery 30 from the determined charge amount (S106). On the other hand, if it is determined that the battery is fully charged, the process proceeds to S107 without performing the correction.
[0046]
Next, the eco-run ECU 40 refers to the correspondence between the accelerator opening and the control end speed stored in the ROM, and determines the engine speed at which the charge control process ends based on the accelerator opening at that time. (S107).
[0047]
As shown in FIG. 3 (b), the correspondence between the accelerator opening and the control end speed is qualitatively such that the control end speed decreases as the accelerator opening increases. As in the case of the correspondence between the accelerator opening and the charge amount, the present embodiment adopts the above-described correspondence relationship, and terminates the torque consumption of the ALT 26 based on the charge control at an earlier stage as the accelerator opening increases. The time required to reach the idling speed is shortened.
[0048]
According to the above-described correspondence, when the accelerator opening is small, the control end rotation speed increases, but in this case, the upper limit is the idling rotation speed which is the target rotation speed. Therefore, the torque consumption of the ALT 26 based on the charge control ends before the idling rotation speed is reached (that is, the torque consumption of the ALT 26 returns to the normal state), and thereafter, the engine rotation speed is basically determined based on the accelerator depression amount. Will be controlled. The reason for this configuration is that in order to finally control the engine speed to follow the idling speed, there is insufficient power in the configuration based on the torque consumption by the ALT 26, and the speed based on the charge amount control. The reason is that by returning to normal engine control without suppression, it is possible for the driver to start and proceed smoothly according to the depression of the accelerator without feeling uncomfortable.
[0049]
Next, the eco-run ECU 40 controls the DC / DC converter 32 so that the charge amount to the battery 34 becomes the determined charge amount (S108). Until S108 is executed for the first time after the first explosion, the charge amount of the battery 34 is set to a predetermined default value (in principle, a value lower than the charge amount determined in S104). It is assumed that the DC / DC converter 32 has been set.
[0050]
Thus, based on the electromotive force generated by the ALT 26, a current corresponding to the determined amount of charge is supplied to the battery 34 via the rectifier 27, the regulator 28, and the DC / DC converter 32, and charging is performed. You. At this time, if the battery 30 is not in the fully charged state, the battery 30 is also charged.
[0051]
Next, the eco-run ECU 40 compares the engine speed with the determined control end speed (S109).
[0052]
If the engine speed is equal to or higher than the control end speed, the DC / DC converter 32 is controlled such that the amount of charge to the battery 34 becomes the predetermined default value (S110), and the process ends. I do.
[0053]
On the other hand, if the engine speed is not equal to or higher than the control end speed, the eco-run ECU 40 compares the value of the counter with the upper limit of the execution time (S111).
[0054]
If the counter value is equal to or more than the upper limit value, the DC / DC converter 32 is controlled so that the amount of charge to the battery 34 becomes the predetermined default value (S112), and the process ends. On the other hand, if the counter value is not equal to or more than the upper limit value, the process returns to S104.
[0055]
FIG. 4 is a diagram conceptually illustrating an example of the degree of increase in the engine speed when the charge amount control is performed (case 1) and when the charge amount control is not performed (case 2). As can be seen from the figure, in case 2, the engine speed overshoots the idling speed and a blow-up occurs, whereas in case 1, the charge amount control is performed during period 100, and It can be seen that changes asymptotically to the idling rotational speed (target rotational speed) without overshooting. In the example shown in Case 1, the charge control is ended when the engine speed reaches the control end speed.
[0056]
As described above, in the present embodiment, instead of directly controlling the ALT 26 by the excitation control, the amount of charge to the battery 34 is controlled through the DC / DC converter 32, thereby controlling the torque consumption of the ALT 26 and the engine speed. The structure which suppresses the rise of is adopted. Since the control characteristic of the charge amount of the secondary battery generally has a better response characteristic than the excitation control, according to the above configuration, the charge amount and, consequently, the torque consumption can be controlled at an appropriate timing. In addition, it is possible to accurately suppress the increase in the number of revolutions of the engine 2 and prevent a blow-up.
[0057]
In particular, as in the present embodiment, by using a lithium battery having good acceptability of electric energy as the battery 34 whose charge amount is to be controlled, better response characteristics can be obtained, and preferable effects can be obtained. it can.
[0058]
Further, in the present embodiment, the upper limit value of the execution time is determined, and the charge amount control is applied within the upper limit time, so that the increase in the engine speed is suppressed more than necessary and the start is delayed. Can be prevented.
[0059]
Furthermore, in the present embodiment, the charge amount control is applied on condition that the rotation speed of the internal combustion engine is within a predetermined range (a range not exceeding the idling rotation speed with the control end rotation speed as an upper limit). When the engine speed is close to the idling speed, it is possible to return to the normal engine control, and it is possible for the driver to start and proceed smoothly without falling short of power and without a sense of incongruity for the driver.
[0060]
Further, in the present embodiment, since the charge amount and the control end rotation speed are determined according to the accelerator opening, the degree of suppression can be changed according to the driver's intention reflected in the accelerator depression amount, A flexible blow-up prevention function can be realized.
[0061]
(Other)
The present invention is not limited to the above embodiment, but can be applied in various modifications.
[0062]
For example, a configuration for realizing a blow-up prevention function by combining the configuration for controlling the amount of charge to the secondary battery of the present invention and the configuration for directly controlling the power generation means based on the conventional excitation control may be used.
[0063]
Further, for example, in the above-described embodiment, a total of two batteries, that is, a 12V lead battery as the battery 30 and a 12V lithium battery as the battery 34 are provided, and the amount of charge to the battery 34 is controlled. The number of batteries to be subjected to charge amount control, the type of battery (battery type), the capacity of the battery, and the like can be changed according to the design.
[0064]
For example, in the above embodiment, the capacities of the battery 30 and the battery 34 are the same, but the capacities of the two may be different. In this case, the battery having the larger capacity may be preferentially charged. Conceivable.
[0065]
Further, for example, in the above embodiment, the batteries 30 and 34 are arranged in parallel with the ALT 26, but instead of such a configuration, the battery 30 is charged based on the electric energy generated by the ALT 26, The battery 34 may be charged based on the electric energy stored in the battery 30, and may be arranged in series. In this case, it is conceivable to provide a DC / DC converter between the battery 30 and the battery 34 and control the amount of charge to the battery 34 (the amount of electric energy transferred from the battery 30 to the battery 34) by adjusting the DC / DC converter. Can be
[0066]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, when starting an engine, it can suppress a blow-up accurately and appropriately, and can improve fuel consumption more.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a system configuration of an internal combustion engine for a vehicle and a control device thereof according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating a flow of a blow-up prevention process according to the embodiment of the present invention.
FIG. 3 is a diagram for explaining a correspondence relationship between an accelerator opening and a charge amount or a control end rotation speed.
FIG. 4 is a diagram conceptually showing the degree of increase in engine speed.
[Explanation of symbols]
2 Engine 2a Crankshaft 4 Torque converter 6 Automatic transmission 6a Output shaft 10 Pulley 10a Electromagnetic clutch 14 Belt 16 Pulley 22 Accessories 26 Alternator 27 Rectifier 28 Regulator 30 Battery 32 DC / DC converter 34 Battery 36 Starter 38 Electric hydraulic pump 40 Eco-run ECU
42 fuel injection valve 44 electric motor 46 throttle valve 48 engine ECU
50 brake ECU

Claims (9)

The present invention is directed to a vehicle including a power generation unit that generates electric power based on the rotation of an internal combustion engine and a secondary battery unit that is charged based on electric power supplied from the power generation unit, and suppresses an increase in the rotation speed of the internal combustion engine. A control device for a vehicle, comprising: control means for controlling the amount of charge to a secondary battery means. The vehicle control device according to claim 1, wherein the control means includes an ECU (Electronic Control Unit) and a DC / DC converter. The vehicle control device according to claim 1, wherein the control unit determines a charge amount of the secondary battery unit based on an accelerator opening. 4. The control device according to claim 1, wherein the control unit controls a charge amount of the secondary battery unit on condition that a rotation speed of the internal combustion engine is within a predetermined range. 5. Vehicle control device. The vehicle control device according to claim 4, wherein the control unit changes the predetermined range based on an accelerator opening. 5. The control device according to claim 1, wherein the control unit controls the amount of charge to the secondary battery unit within an upper limit time set for a time for performing the control of the amount of charge. 6. Vehicle control device. The secondary battery unit includes at least a first secondary battery that is charged based on electric power from a power generation unit and a second secondary battery that is charged based on electric power from the first secondary battery. Prepare,
The vehicle control device according to any one of claims 1 to 6, wherein the control unit controls a charge amount charged from the first secondary battery to the second secondary battery. A power generation step of generating power based on the rotation of the internal combustion engine,
A charging step of charging the secondary battery based on the electric power generated in the power generation step;
A control step of controlling an amount of charge to a secondary battery in order to suppress an increase in the number of revolutions of the internal combustion engine. A power generation step of generating power based on the rotation of the internal combustion engine,
A charging step of charging the secondary battery based on the electric power generated in the power generation step;
A computer-readable recording medium storing a program for causing a computer to execute a control step of controlling a charge amount of a secondary battery to suppress an increase in the rotation speed of an internal combustion engine.

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