JP2004135371A - Electrically propelled vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrically propelled vehicle which can travel without hindrance even in the case that an abnormality occurs in a part of a power source. <P>SOLUTION: The electrically propelled vehicle is equipped with two systems of drive sources for outputting power independently in left and the right directions. The left drive source is equipped with a fuel cell 22, a battery 21, and a motor 25 which is driven by power from them. The right drive power source has the same constitution. The motor in each system is coupled with a drive shaft 21 via a gear box 40. Moreover, auxiliary equipment such as a power steering, etc. necessary for travelling is connected to each system. In a normal mode, the motor and the auxiliary equipment are supplied with power for travelling from both the power sources. In the case that an abnormality occurs in the left power source, the operation of the auxiliary equipment is secured to enable travelling by regenerating a part of the the output of the right fuel cell 32 by means of the motor 25 and supplying it to the auxiliary equipment. In the case that an abnormality occurs in the right power source, the operation of the auxiliary equipment is secured by regenerating it conversely by the right motor 35. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric vehicle equipped with a DC power supply.
[0002]
[Prior art]
2. Description of the Related Art Various electric vehicles that run by driving a motor by a DC power supply have been proposed. For example, Patent Document 1 discloses a vehicle in which two electric motors having different output characteristics are connected to a drive shaft and travels using a high-voltage power supply. In recent years, a fuel cell that generates power by an electrochemical reaction between hydrogen and oxygen has attracted attention as a DC power supply.
[0003]
[Patent Document 1]
JP-A-11-252993
[Problems to be solved by the invention]
However, the electric vehicle according to the related art has a problem that when the supply of power from the DC power supply is cut off, the vehicle cannot run even if the motor is normal. An object of the present invention is to solve the above-described problem and to provide a vehicle that can continue running even if a failure occurs in a power supply.
[0005]
[Means for Solving the Problems and Their Functions and Effects]
In order to solve at least a part of the problems described above, according to the present invention, an electric vehicle includes two power sources that output power to a drive shaft that outputs driving force. The power source has a DC power supply for each system and an electric motor driven by the DC power supply. By doing so, since a DC power supply is provided for each system, even if an abnormality occurs in one system, it is possible to travel using the other system. In addition, since a DC power supply and a motor are provided for each system, there is an advantage that the above-described redundancy can be secured while avoiding complicated control of each system.
[0006]
In the electric vehicle of the present invention, when a predetermined accessory driven by a DC power supply is connected to each system, the presence or absence of an abnormality in the DC power supply is detected, and when an abnormality is detected in one of the power supplies, The following control may be applied. The motor of one system (hereinafter, referred to as “abnormal system”) having an abnormality in the DC power supply is driven by the motor of the other system (hereinafter, referred to as “normal system”) having no abnormality, and Electric power generation may be performed by an electric motor. By doing so, even when an abnormality occurs in the power supply, it is possible to secure power to the auxiliary equipment. In order to realize this power generation, it is preferable that the electric motors of the respective systems are provided in a state where power can be transmitted directly or indirectly to each other.
[0007]
In order to supply power to the auxiliary equipment of the abnormal system, it is also possible to adopt a method in which a connection mechanism for electrically connecting the normal system and the abnormal system is arranged between the two systems. Such a connection mechanism may be, for example, a relay device that closes a circuit when an abnormality occurs in one power supply. However, when such a relay device is used, when the current supplied from the DC power supply is very large, there is a possibility that a spark may be generated near the contact at the moment when the circuit is closed, which may cause adverse effects. On the other hand, the method of causing the electric motor of the abnormal system to generate electric power has the advantage that electric power can be supplied to the auxiliary equipment without causing such adverse effects.
[0008]
In the present invention, power generation by the motor of the abnormal system may be started immediately when an abnormality occurs in the power supply. When a power storage device that assists the DC power supply is provided for each system, the operation may be started when the amount of power stored in the power storage device provided in the abnormal system becomes equal to or less than a predetermined value. According to the latter aspect, the power of the normal system can be effectively used for traveling at least during a period when the power supply of the auxiliary device is performed from the power storage device of the abnormal system.
[0009]
The control described above is particularly useful when the auxiliary equipment of the abnormal system includes at least one of the steering system, the braking system, and the drive system of the electric vehicle, that is, the auxiliary equipment that is indispensable for traveling of the electric vehicle. . As a steering system auxiliary device, a so-called power steering compressor is included. The auxiliary equipment of the braking system includes so-called brake oil, an air compressor, and a compressor for assisting the amount of depression of the brake. The drive system accessories include, for example, a transmission oil pump and a cooling pump.
[0010]
In the present invention, the operation of some of the auxiliary machines provided in the abnormal system may be suppressed. Stoppable auxiliary devices that are allowed to stop during running of the electric vehicle may be set in advance. The stoppable auxiliary machine includes, for example, an air-conditioning system, a lighting system in a vehicle, and a sound system.
[0011]
In the present invention, control may be applied in which, when the presence or absence of a decrease in the output of the DC power supply is detected, the output distribution of the required power to be output from the drive shaft differs between the two systems. It is preferable to set the output distribution according to the output decrease so that the output of the system in which the output decrease is detected is lower than the output of the other system. By doing so, the required power can be ensured by compensating for the decrease in output in one system and the decrease in output in the other system. The decrease in output includes not only a case where power supply from the DC power supply becomes impossible, but also a case where normal output cannot be obtained due to aging or other factors.
[0012]
In the present invention, as the DC power supply, for example, various power supplies such as a primary battery, a secondary battery, and a capacitor can be used, but from the viewpoint of energy efficiency, a fuel cell is preferable. When a fuel cell is used, it is necessary to control the supply amount of a fuel gas such as hydrogen and the supply amount of an oxidizing gas such as oxygen according to a required power generation amount. In the present invention, since a fuel cell is provided for each of the two systems, such control is facilitated, and there is an advantage that the operation of the fuel cell can be stabilized.
[0013]
The present invention may be configured as a power output device that outputs power from a drive shaft, or may be configured as a control method for an electric vehicle or a power output device, in addition to the above-described embodiment as an electric vehicle.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described in the following sections.
A. Device configuration:
B. Operation control:
C. Set target value:
D. Modification:
[0015]
A. Device configuration:
FIG. 1 is an explanatory diagram showing a schematic configuration of an electric vehicle as an embodiment. This electric vehicle has two independent drive sources for outputting power on the right and left sides. The left drive source has a polymer electrolyte fuel cell 22 as a main power source and a battery 21 as an auxiliary power source. The electric power supplied from these power supplies is converted into AC by an inverter 24 as a drive circuit, and is supplied to an AC motor 25.
[0016]
The right driving source has the same configuration. As the right driving source, a fuel cell 32, a battery 31, an inverter 34, and an AC motor 35 are provided. In this embodiment, the output characteristics and the capacitance of the right driving source and the left driving source are the same. The fuel gas to the fuel cells 22 and 32 is supplied from a common hydrogen tank.
[0017]
The rotating shaft 26 of the motor 25 and the rotating shaft 36 of the motor 35 are connected to gears 42 and 43 in a gear box 40, respectively. The gears 42 and 43 are spur gears that mesh with the drive gear 41. The drive shaft 41 is coupled to the drive gear 41. The power of each of the motors 25 and 35 is output to the drive shaft 12 via each gear of the gear box 40 and transmitted to each of the wheels 14L and 14R via the differential gear 13.
[0018]
In this embodiment, auxiliary drive circuits 23 and 33 for driving various auxiliary machines by receiving power supply are connected to the respective drive sources. The accessory drive circuits 23 and 33 include a pump for supplying fuel gas and cooling water to the fuel cells 22 and 32, an oil pump for power steering, an outlet for supplying power to electric devices of the vehicle, and a compressor for cooling the battery 21. , A compressor for air conditioning, an electric heater for air conditioning, an air compressor for brakes, and the like.
[0019]
Among them, pumps for supplying fuel gas and cooling water to the fuel cells 22 and 32, oil pumps for power steering, and air compressors for brakes are provided on both the left and right sides, but are used to stably drive the vehicle. Is positioned as an essential accessory for which both are desired to operate. The air-conditioning compressor and the air-conditioning electric heater are not necessarily essential for the running of the vehicle. Therefore, if an abnormality occurs during running, it is positioned as a stoppable auxiliary machine that can automatically stop operation. Has been. The outlet for supplying power to the electrical equipment of the vehicle and the compressor for cooling the battery 21 can be positioned at any position, but in the present embodiment, they are positioned as essential accessories in consideration of safety. These categories of accessories are stored in the control unit 10 in advance.
[0020]
Each part of the vehicle is controlled by the control unit 10. The control unit 10 is configured as a microcomputer having a CPU, a ROM, and a RAM therein, and controls the operation of each part of the vehicle according to a control program prepared in the ROM.
[0021]
In the drawing, various signal lines connected to the control unit 10 to realize this control are illustrated by broken lines. The sensor signals input to the control unit 10 include an accelerator opening sensor 11; a vehicle speed sensor 12s; motor rotation speed sensors 25s and 35s; sensors 22s and 32s for detecting abnormalities of the fuel cells 22 and 32; The remaining capacity sensors 21s and 31s for detecting the remaining capacity (SOC) are included. The abnormality detecting sensors 22 s and 32 s are sensors for detecting various parameters that notify the abnormality of the fuel cells 22 and 23. Such parameters include, for example, the number of revolutions of a compressor for supplying fuel gas and oxidizing gas to the fuel cells 22 and 32, the temperature of the fuel cells 22 and 32, the supply pressure of fuel gas and oxidizing gas, and the fuel cells 22 and 32. Can be used.
[0022]
The output signals from the control unit 10 include output control signals for the fuel cells 22 and 32; control signals for the auxiliary drive circuits 23 and 33; control signals for the inverters 24 and 34, and the like.
[0023]
B. Operation control:
FIG. 2 is a flowchart of the operation control process. This is a process that the control unit 10 repeatedly executes while the electric vehicle is running. When this process is started, the control unit 10 first inputs an accelerator opening, a vehicle speed, and the like as parameters used for control (step S10). In various variables used in the present control processing, R means a value for the right system, and L means a value for the left system.
[0024]
Next, various required powers described below are set based on these parameters (step S12). The total required power Ptr is required power for driving the vehicle, and is set by referring to a map that gives the total required power Ptr in advance in relation to the accelerator opening and the vehicle speed. The auxiliary machine powers PRa and PLa are required powers for driving the auxiliary machines, and fluctuate depending on the operating state of each auxiliary machine. Charging power PRb, PLb is power for charging batteries 21, 31. In the present embodiment, when the remaining capacity of the batteries 21 and 31 falls below a preset lower limit, charging is started. Therefore, the charging powers PRb and PLb are determined according to the remaining capacity at that time. When the remaining capacity of the battery 31 is equal to or larger than the lower limit, the charging power PRb and PLb become 0 because charging is not necessary.
[0025]
When the various powers are set in this way, the control unit 10 detects whether the operating state of the fuel cells 22, 32 is normal (step S14). In the present embodiment, the operating state of each of the fuel cells 22 and 32 is specified in three categories: normal, reduced output, and abnormal. The normal state is a state in which the fuel cells 22 and 32 can output 90% or more of the power that can be originally output. The output decrease refers to a state in which the output of the fuel cells 22 and 32 is 80% or more and less than 90% due to aging or other causes, although the operation is not hindered. The abnormality is a state where the operation of the fuel cells 22 and 32 cannot be continued, or a state where the output is lower than 80%. The division of the operation state can be arbitrarily set, and only the normal / abnormal state may be set without providing the “output drop” state. Further, an output range that defines each section can be set arbitrarily.
[0026]
When it is determined that both the fuel cells 22 and 32 are abnormal (step S16), the control unit 10 determines that the vehicle cannot continue running, and stops the system (step S18). At the same time, the driver may be notified that the fuel cells 22 and 23 are abnormal. In the present embodiment, even when it is determined that the output of both the fuel cells 22 and 32 is decreased, the same treatment as the abnormality is performed.
[0027]
In other cases, the control unit 10 sets a target value according to the operation state of the fuel cells 22 and 32 (Step S20). The target electric power values ER and EL are target electric power values to be output from the fuel cells 22 and 32. The motor target powers MR and ML are target powers to be output from the motors 25 and 35. When the target power is positive, it means power running of the motors 25 and 35, and when the target power is negative, it means regeneration. How to set these target values will be described later.
[0028]
When the target values are set in this manner, the control unit 10 sets the upper limit values ERmax and ELmax of the outputable power and the motor rotation speed NR as parameters for controlling the operations of the fuel cells 22 and 32 and the motors 25 and 35. , NL (Step S22). Further, the upper limit guard of the motor target powers MR and ML is applied by the calculation of the following equation (step S24).
MR = MIN (MR, ERmax);
ML = MIN (ML, ELmax);
Here, MIN is an operator meaning that the minimum value of two values is selected.
[0029]
By the upper limit guard, the motors 25 and 35 are driven within a range of electric power that can be supplied from the fuel cells 22 and 32. The control unit 10 sets the target torques TR and TL of the motor by dividing the target powers MR and ML thus set by the motor speeds NR and NL (step S26). The power supply and the motor are controlled using the torque and the power target values ER and EL as command values (step S28).
[0030]
C. Set target value:
FIG. 3 is an explanatory diagram showing a method of setting a target value. In this embodiment, the operating states of the fuel cells 22 and 23 are classified into five combinations. The control unit 10 sets a target value using the following equation according to each classification.
[0031]
Case A: When both fuel cells are normal In this case, the total required power Ptr is output equally from each system. Since the auxiliary powers PRa and PLa and the charging powers PRb and PLb are powers unique to each system, they are output in the respective systems. Therefore, each target value is set as follows.
Power target value;
ER = Ptr / 2 + PRa + PRb;
EL = Ptr / 2 + PLa + PLb;
Motor target power;
MR = Ptr / 2;
ML = Ptr / 2;
[0032]
Case B: When the output of the fuel cell on the right (R) is reduced. In this case, the total required power Ptr is output from each system in a different distribution. Since the output of the right system is reduced, the distribution ratio on the right is set lower than that on the left. Since the auxiliary powers PRa and PLa and the charging powers PRb and PLb are powers unique to each system, they are output in the respective systems. Therefore, each target value is set as follows.
Power target value;
ER = Ptr / 2 × k + PRa + PRb;
EL = Ptr / 2 × (2-k) + PLa + PLb;
Motor target power;
MR = Ptr / 2 × k;
ML = Ptr / 2 × (2-k);
[0033]
k is a distribution ratio, and set values in the present embodiment are shown on the lower side of FIG. The range between the available output powers p1 and p2 is the range in which the output is determined to be reduced. In this embodiment, “p1 = 80%, p2 = 90%” is set. Although the distribution ratio k can be set arbitrarily, in the present embodiment, as shown in the figure, the distribution ratio k is set to change linearly in the range of 0.8 to 1.0 in the above range. According to this setting, when the output of the right fuel cell is reduced to 80%, the power to be output from the right system is reduced to 0.8 times the normal time. On the other hand, the power to be output from the left system is increased to 1.2 times that in the normal state. In this way, the output decrease of the right system can be compensated for by the left system, and the output of the total required power PTr can be secured.
[0034]
Case C: When the output of the left (L) fuel cell is reduced. In this case, the target values can be set as follows in the same way as in Case B.
Power target value;
ER = Ptr / 2 × (2-k) + PRa + PRb;
EL = Ptr / 2 × k + PLa + PLb;
Motor target power;
MR = Ptr / 2 × (2-k);
ML = Ptr / 2 × k;
The distribution ratio k uses the same setting as in the case B.
[0035]
Case D: When the right (R) fuel cell is abnormal In this case, since the output from the right fuel cell cannot be obtained, all the required power is output from the left system. In order for the vehicle to run stably, it is necessary to supply power to the essential auxiliary equipment connected to the right-hand system, and in case D, this auxiliary equipment power PRa is secured in two ways. . One is power from the battery 31 of the right system. The other is electric power obtained by regenerating a part of the power output from the normally operating left-side motor 25 by the right-side motor 35.
[0036]
In the present embodiment, the battery 31 is positioned as an auxiliary power supply for the fuel cell 32 that outputs a shortage when the fuel cell 32 cannot output the requested power. In case D, since the fuel cell 32 cannot output power, the power target value ER for the right system can be regarded as the output target to the battery 31 as it is.
[0037]
Based on the above concept, in case D, each target value is set as follows.
Power target value;
ER = PRa × FS;
EL = Ptr + PLa + PLb + PRa (1-FS);
Motor target power;
MR = -PRa * (1-FS);
ML = Ptr + PRa × (1-FS);
Since the target power MR of the right motor 35 is set to a negative value, the motor 35 regenerates electric power.
[0038]
FS is the distribution ratio of the power to be supplied from the battery 31, and the set value in the present embodiment is shown on the lower side of FIG. The distribution ratio FS is set according to the remaining capacity SOC of the battery 31. The range where the SOC is s2 or more is a range in which the battery 31 can be considered to be in a fully charged state. In this state, the auxiliary machine power PRa is all supplied from the battery 31. The range where the SOC is equal to or less than s1 is a range in which the battery 31 can be regarded as having insufficient remaining capacity. In this state, the battery 31 does not supply the auxiliary power PRa to avoid power consumption. In the range of s1 to s2, battery 31 outputs a part of auxiliary machine power PRa at a distribution rate corresponding to the value of SOC. Of the auxiliary power PRa, the shortage of the output from the battery 31 is compensated by regeneration. The setting of the distribution ratio FS is not limited to this, and may be a discontinuous setting that takes either 0 or 1 at a predetermined SOC. In case D, the distribution ratio FS may be constantly set to zero.
[0039]
The auxiliary machine power PRa may be a value equivalent to that in a normal state, or may be a value when the stoppable auxiliary machine is stopped. In the present embodiment, in order to suppress power consumption in the right system, in case D, the stoppable auxiliary machines are stopped. At first, all the auxiliary machines may be operated, and the stoppable auxiliary machines may be stopped when the remaining capacity of the battery 31 falls below a predetermined value.
[0040]
When the above-described target power ER cannot be output from the left fuel cell 32, the upper limit guard is applied to a range in which the target power ER can be output, and the charging power PLb and the left motor target power ML are reduced. The motor target power MR on the right holds the above set value because power regeneration is essential to drive the auxiliary machine. By doing so, the power output from the drive shaft 12 becomes lower than the power requested by the driver, but the traveling of the vehicle can be continued.
[0041]
Case E: When the fuel cell on the left (L) is abnormal In this case, the respective target values can be set as follows in the same way as in Case D.
Power target value;
ER = Ptr + PRa + PRb + PLa × (1-FS);
EL = PLa × FS;
Motor target power;
MR = Ptr + PLa × (1-FS);
ML = -PLa × (1-FS);
Since the target power ML of the left motor 25 is set to a negative value, the motor 25 regenerates electric power.
[0042]
FIG. 4 is an explanatory diagram showing a power transmission state in case E. The state where the abnormality is present in the left fuel cell 22 and the remaining capacity of the battery 21 is s1 or less, that is, the distribution ratio FS is 0 is shown.
[0043]
According to the target value setting in case E described above, part of the power output from the right fuel cell 32 is supplied to the battery 31 as charging power PRb (arrow A in the figure). A part is supplied to the left accessory drive circuit 33 as the accessory power PLa (arrow B). The remainder is temporarily output as the power of the motor 35 via the inverter 34 (arrow C). This power is distributed by the gear box 40, and an amount corresponding to the total required power Ptr is supplied to the drive shaft 12 (arrow D). The remainder is regenerated by the motor 25 as the auxiliary power PRa and supplied to the auxiliary drive circuit 23 of the right system (arrow F).
[0044]
According to the electric vehicle of the embodiment described above, even if the output of one of the fuel cells 22 and 32 is reduced or an abnormality occurs, the vehicle runs while compensating for the shortage with the electric power from the other system. be able to. In addition, the power supply system is provided independently on the left and right, but by regenerating power with the motor of the system in which the abnormality has occurred, it is possible to secure power supply to auxiliary equipment even in the event of an abnormality, Can continue.
[0045]
D. Modification:
FIG. 5 is an explanatory diagram illustrating a schematic configuration of an electric vehicle as a modification. It differs from the embodiment in that a connector 15 for connecting the right and left systems is provided. The connector 15 is connected under the control of the control unit 10A when an abnormality occurs in one power supply. The connector 15 may be a normal relay or a circuit that controls energization by a switching element.
[0046]
According to the modification, in addition to the control in the embodiment, a failure of the inverters 24, 34 or the motors 25, 35 can be dealt with. When detecting an abnormality in these systems, the control unit 10A stops the inverter and the motor of the abnormal system and connects the connector 15. By doing so, both the left and right power supplies are connected in parallel to the normal system inverter and motor. Therefore, traveling can be continued while avoiding applying an excessive load only to the fuel cell of the normal system.
[0047]
Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it goes without saying that various configurations can be adopted without departing from the spirit of the present invention. For example, the above-described control processing may be realized by software or hardware.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a schematic configuration of an electric vehicle as an embodiment.
FIG. 2 is a flowchart of an operation control process.
FIG. 3 is an explanatory diagram showing a method for setting a target value.
FIG. 4 is an explanatory diagram showing a power transmission state in case E.
FIG. 5 is an explanatory diagram showing a schematic configuration of an electric vehicle as a modified example.
[Explanation of symbols]
10, 10A ... control unit 12 ... drive shaft 13 ... differential gears 14R, 14L ... wheels 15 ... connectors 21, 31 ... batteries 21s, 31s ... remaining capacity sensors 22, 32 ... fuel cells 22s, 32s ... abnormality detection sensor 23 , 33 ... Auxiliary equipment drive circuits 24, 34 ... Inverters 25, 35 ... AC motors 25s, 35s ... Rotation speed sensors 26, 36 ... Rotating shaft 40 ... Gear box 41 ... Drive gear 42 ... Gear

Claims (8)

An electric vehicle,
A driving shaft for outputting driving force,
Two power sources that output power to the drive shaft,
An electric vehicle including a DC power source for each system and an electric motor driven by the DC power source. The electric vehicle according to claim 1,
A predetermined accessory driven by the DC power supply for each system,
A detection unit that detects whether or not the DC power supply is abnormal;
When it is detected that one of the systems is an abnormal system having an abnormality in the DC power supply and the other system is a normal system having no abnormality, the motor of the abnormal system is driven by the motor of the normal system. And a power generation control unit that supplies power to the auxiliary equipment of the abnormal system by causing the electric motor of the abnormal system to generate electric power. The electric vehicle according to claim 2,
For each system, having a power storage device to assist the DC power supply,
An electric vehicle that operates when the amount of power stored in a power storage device provided in the abnormal system becomes equal to or less than a predetermined value. The electric vehicle according to claim 2 or 3, wherein
An electric vehicle, wherein the auxiliary device of the abnormal system includes at least one of a steering system, a braking system, and a drive system of the electric vehicle. The electric vehicle according to any one of claims 2 to 4,
A setting storage unit that stores in advance setting contents of a part of the auxiliary equipment of the abnormal system as a stoppable auxiliary equipment that is allowed to stop during traveling of the electric vehicle;
An electric vehicle comprising: an accessory control unit that suppresses the operation of the stoppable auxiliary machine with respect to the abnormal system when the abnormality is detected. The electric vehicle according to any one of claims 1 to 5,
An input unit for inputting required power to be output from the drive shaft,
A detection unit that detects whether or not the output of the DC power supply has decreased;
When a decrease in output is detected in the DC power supply of one system, the operation of each motor is controlled so that the output of the motor of the system becomes lower than the output of the motor of the other system in accordance with the decrease in output. The electric vehicle provided with the electric motor control part which performs. The electric vehicle according to any one of claims 1 to 6, wherein the DC power supply is a fuel cell. A method for controlling an electric vehicle, comprising:
The electric vehicle is
A driving shaft for outputting driving force,
Two power sources that output power to the drive shaft,
The power source includes a DC power supply for each system, a motor driven by the DC power supply, and a predetermined auxiliary machine driven by the DC power supply,
Detecting the presence or absence of an abnormality in the DC power supply;
When it is detected that one of the systems is an abnormal system having an abnormality in the DC power supply and the other system is a normal system having no abnormality, the motor of the abnormal system is driven by the motor of the normal system. Supplying electric power to the auxiliary equipment of the abnormal system by causing the electric motor of the abnormal system to generate electric power.

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