JP2009301981A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system in which a fault caused by oil is prevented such as effective prevention of flowing-in of oil in the fuel cell when using a roots pump for a pressure pump to pressurize and eject a reaction gas, and further a mounting performance is improved. <P>SOLUTION: The fuel cell system includes a hydrogen pump 46 which is the roots pump of two-axis rotating pump that is a pressure pump to pressurize and eject hydrogen gas being a reaction gas and a control part. The hydrogen pump 46 includes two cocoon shape rotors 72, 74 which are arranged on the outer diameter side of two rotor axes of rotation 68, 70 that are provided in a casing 66 rotatably mutually in parallel and are opposed to each other, and two motors 58, 60 of which the respective motor drive shafts 86, 88 are constructed by a part of each rotor axes of rotation 68, 70. The control part controls rotation drive of each motors 58, 60 so as to rotate in the reverse direction by synchronizing the two motors 58, 60. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell system including a fuel cell that generates electric power by an electrochemical reaction of a reaction gas, and a pressurizing pump that pressurizes and discharges the supplied reaction gas.

  Conventionally, a fuel cell system having a fuel cell stack, which is a fuel cell that generates power by an electrochemical reaction between a fuel gas that is a reaction gas, for example, a hydrogen gas containing hydrogen, and an oxidizing gas that is a reaction gas, for example, air, has been considered. ing. The fuel cell stack is configured by stacking a plurality of sets of fuel cell units, for example, a membrane-electrode assembly (MEA) composed of an anode side electrode, an electrolyte membrane and a cathode side electrode and a separator. That is, each fuel cell is configured by arranging an anode side electrode on one side of an electrolyte membrane made of a polymer ion exchange membrane, a cathode side electrode on the other side, and further providing separators on both sides. is doing. A plurality of such fuel battery cells are stacked and sandwiched between current collector plates, insulating plates, and end plates to constitute a fuel cell stack that generates a high voltage.

  In such a fuel cell, a fuel gas is supplied to the anode side electrode and an oxidizing gas is supplied to the cathode side electrode. As a result, the fuel gas and the oxidizing gas are subjected to an electrochemical reaction to generate an electromotive force.

  Further, in the fuel cell system, a fuel gas supply channel for supplying fuel gas to such a fuel cell stack, a fuel gas system discharge channel for discharging the fuel gas system gas from the fuel cell stack, and a fuel cell stack A circulation flow path for returning the fuel gas gas discharged from the fuel cell stack to the fuel cell stack, an oxidizing gas supply flow path for supplying oxidizing gas to the fuel cell stack, and discharging the oxidizing gas gas from the fuel cell stack It is considered to include an oxidizing gas-based discharge flow path. Further, it is considered that a pressurizing pump that pressurizes and discharges the fuel gas-based gas supplied to the circulation flow path is provided, and the pressurizing pump is constituted by a Roots pump that is a volumetric compression pump.

  The Roots-type pump uses two saddle-shaped rotors that rotate in opposite directions in synchronization with each other, compresses the volume of fuel gas gas fed from the suction port, and then discharges it through the discharge port. Conventionally, in such a Roots type pump, in order to drive two saddle-shaped rotors synchronously, gears called timing gears are respectively fixed to two rotating shafts to which the saddle-shaped rotors are fixed, It is considered that both gears are meshed and one of the two rotating shafts is driven by a motor. In this case, one rotating shaft driven by the motor serves as a driving shaft, and the other rotating shaft of the two rotating shafts serves as a driven shaft to which rotational force is transmitted from one rotating shaft via a gear.

  Patent Document 1 discloses a brushless DC motor including a pair of motor rotors connected to a pair of rotating shafts, which is a positive displacement compressor in which roots-type rotors provided on a pair of rotating shafts mesh with each other and rotate in opposite directions. , And the motor rotor is configured to rotate in opposite directions synchronously with each other.

  Further, in Patent Document 2, a first rotating shaft and a second rotating shaft are housed in a housing, and a cylindrical upper rotor is engaged with the rotating shaft on the upper side of each rotating shaft, and a lower rotor is engaged with the rotating shaft on the lower side. A volumetric vacuum pump is described in which screw grooves are formed on the outer peripheral surface of each rotor so as to mesh with each other, and a first rotating shaft and a second rotating shaft are rotated by an AC servo motor. The lower screw groove is a first pump portion, and the upper screw groove is a second pump portion. Moreover, it is supposed that a roots type may be sufficient as a form of a 1st pump and a 2nd pump.

JP 2000-329084 A JP-A-11-241694

  In the case of a Roots type pump that has been conventionally considered to be used as a pressure pump constituting a fuel cell system, a gear called a timing gear is fixed to the drive shaft and the driven shaft in order to rotate the driven shaft. The two gears are engaged with each other. For this reason, it is considered to increase the durability of the gears by using oil for lubricating both gears. However, when oil is used in this way, there is room for improvement in terms of effectively preventing the oil from flowing into the fuel cell stack when the pump fails. If oil flows into the fuel cell stack, the fuel cell stack needs to be replaced. In addition, when oil is used, it is necessary to provide an oil seal or the like between the gear rotor and the part where it is necessary to prevent the inflow of oil, such as a saddle type rotor part. The resistance may cause the rotational resistance of the pump driving motor to be excessively high. In this case, the cost required for maintenance and inspection of the fuel cell system becomes high.

  Further, when only one motor fixed to the drive shaft is used as a drive source for rotating the drive shaft and the driven shaft, the Roots pump is increased in size due to an increase in the diameter of the motor, etc. There is a possibility that the degree of freedom of installation with respect to the installation space for installing the is greatly limited.

  Further, when the fuel cell system is mounted on a vehicle and used for mounting on a fuel cell vehicle that supplies power directly to a driving motor that is a driving source of the vehicle or via a power storage unit such as a battery, the fuel cell system There is a possibility that the fuel cell vehicle may be used or left in a low temperature environment, such as when the battery vehicle is left in a low temperature environment, such as below freezing, for a long period of time. If it freezes, there is a possibility that the fuel cell system cannot be operated or restarted effectively. For this reason, in a roots pump for a fuel cell system, it is desired to realize a means that makes it difficult to freeze components effectively even when used or left in a low temperature environment.

  In the above description, the inconvenience that occurs when the pressure pump that pressurizes and discharges the fuel gas is a Roots-type pump has been described. However, it is provided upstream of the oxidizing gas supply flow path to pressurize and discharge the oxidizing gas. The same inconvenience may occur when a roots type pump is used for pressurizing and discharging other reaction gases such as an air compressor. In addition, a pressure pump that pressurizes and discharges fuel gas system gas, or an air compressor that pressurizes and discharges oxidizing gas, etc. When using a biaxial rotary pump, the same inconveniences as described above may occur. The biaxial rotary pump has two rotatable rotor rotating shafts provided in parallel to each other, and the outer peripheral surfaces of a saddle-shaped rotor, a screw-shaped rotor, etc. provided on the outer diameter side of the two rotor rotating shafts are not It is necessary to provide a rotor having a cylindrical surface and regulate the phase relationship between the two rotor rotation shafts.

  On the other hand, neither of Patent Documents 1 and 2 discloses the use of a two-shaft rotary pump such as a Roots-type pump in a fuel cell system, including matters suggesting this.

  The present invention has been invented to solve at least one of the above-mentioned problems. An object of the present invention is to provide a fuel cell system in which a pressure pump for pressurizing and discharging a reaction gas is a biaxial shaft such as a roots pump. When using a rotary pump, it is intended to eliminate problems caused by oil, such as effectively preventing oil from flowing into the fuel cell, and to improve mountability.

  A fuel cell system according to the present invention is a fuel cell system comprising a fuel cell that generates electricity by an electrochemical reaction of a reaction gas, a pressurizing pump that pressurizes and discharges the supplied reaction gas, and a control unit. The pressure pump is provided in the casing with two rotor rotation shafts provided rotatably in parallel to each other, two rotor rotation shafts provided on the outer diameter side of each rotor rotation shaft, and the casing facing each other. Two-axis rotation provided with a suction port for taking in the reaction gas, a discharge port provided in the casing and for sending out the reaction gas, and two motors constituting each motor drive shaft by a part of each rotor rotation shaft The fuel cell system is characterized by controlling the rotational drive of each motor so that the two motors are rotated in the reverse direction in synchronization.

  According to the fuel cell system described above, since the motor drive shafts of the two motors are constituted by a part of the two rotor rotation shafts provided with the two rotors, the two rotor rotation shafts are connected to the gear mechanism. It can be rotated by two motors without intervention. Therefore, unlike the case where two rotor rotation shafts are rotated by one motor, there is no need to provide a gear mechanism having gears that mesh with the two rotor rotation shafts with a large force. Therefore, it is not necessary to use oil for gear lubrication, oil flows into the fuel cell, sliding resistance due to the oil seal occurs, and the cost required for maintenance and inspection of the fuel cell system increases. Inconvenience caused by oil can be effectively prevented. In addition, since each motor only needs to drive two rotor rotation shafts that are different from each other, each motor can be reduced in size, and the degree of freedom of installation of the pressure pump in the installation space of the pressure pump can be reduced. Improvements can be made.

  In the fuel cell system according to the present invention, preferably, the outer peripheral surfaces of the two rotors are non-cylindrical surfaces, and each motor is rotated when the phase relationship between the two rotor rotation shafts changes. The rotational torque required to make it change.

  Moreover, in the fuel cell system according to the present invention, preferably, the pressurizing pump includes two saddle-shaped rotors that are provided on the outer diameter side of each rotor rotating shaft and are two rotors facing each other. It is a volume compression type Roots type pump type.

  In the fuel cell system according to the present invention, preferably, two gears that mesh with each other for synchronizing the rotations are not coupled to the two rotor rotation shafts.

  According to the fuel cell system, gears can be eliminated or reduced.

  In the fuel cell system according to the present invention, preferably, the two motors are provided on both sides of the casing.

  According to the fuel cell system described above, the heat generated with the rotation of the two motors from both sides of the casing is easily and efficiently transmitted to the components in the casing efficiently. Therefore, when the fuel cell system is mounted on a vehicle and used for mounting on a fuel cell vehicle that supplies electric power directly to a driving motor that is a driving source of the vehicle or via a power storage unit such as a battery, the fuel cell vehicle Even when used in a low-temperature environment, the components of the pressurizing pump can be made difficult to freeze effectively, and the fuel cell system can be operated and restarted easily.

  In the fuel cell system according to the present invention, preferably, the control unit rotates or stops one of the two motors at a constant speed and simultaneously accelerates or decelerates the other motor. Rotation control rotational torque detecting means for detecting rotational torque necessary to rotate at least one of the two motors when rotating the motors synchronously, and at least one of the two motors And an optimum condition motor drive control means for controlling the drive of the two motors so that the two motors rotate in synchronism under the optimum conditions that minimize the detected rotational torque.

  According to the fuel cell system described above, even when the phase difference between the two motors deviates from the appropriate phase difference that minimizes the rotational torque required to rotate the two motors, The phase difference can be corrected to an appropriate phase difference, and energy consumption for driving the motor can be reduced.

  Further, in the fuel cell system according to the present invention, preferably, the rotation control rotational torque detecting means includes two rotation control units when the power generation operation of the fuel cell is stopped or when the torque command for the load connected to the fuel cell is constant. At least one of the two motors in the case where one of the motors is rotated or stopped at a constant speed and at the same time the other motor is accelerated or decelerated and the two motors are rotated synchronously The rotational torque necessary to rotate the is detected.

  According to the above fuel cell system, the rotational torque of at least one motor can be detected by the rotational control rotational torque detecting means in a situation where the required power generation amount for the fuel cell is small or the fluctuation of the required power generation amount hardly occurs. For this reason, the detection accuracy of the rotational torque of the motor can be effectively increased, and the energy consumption for driving the motor can be reduced more effectively. In addition, it is possible to suppress a decrease in the merchantability of products that use the fuel cell system.

  Further, in the fuel cell system according to the present invention, preferably, the fuel cell system is mounted on a vehicle and used as a vehicle-mounted fuel cell system that supplies electric power directly or via a power storage unit to a traveling motor that is a driving source of the vehicle. Further, the rotation control rotational torque detecting means rotates or stops one of the two motors at a constant speed and accelerates or accelerates the other motor when a fuel cell start command signal is input from the vehicle side. After decelerating, the rotational torque required to rotate at least one of the two motors when the two motors are rotated synchronously is detected.

  According to the fuel cell system described above, the rotational torque of at least one motor is detected by the rotational control rotational torque detecting means in a situation where the required power generation amount for the fuel cell is small, is 0, or the fluctuation of the required power generation amount hardly occurs. Can be detected. For this reason, the detection accuracy of the rotational torque of the motor can be effectively increased, and the energy consumption for driving the motor can be reduced more effectively. In addition, it is possible to suppress a decrease in the merchantability of a fuel cell vehicle using the fuel cell system.

  Further, in the fuel cell system according to the present invention, preferably, the fuel cell system is mounted on a vehicle and used as a vehicle-mounted fuel cell system that supplies electric power directly or via a power storage unit to a traveling motor that is a driving source of the vehicle. Further, the rotation control rotational torque detecting means rotates one of the two motors at a constant speed or stops at the same time when the fuel cell start / stop command signal is input from the vehicle side. After acceleration or deceleration, a rotational torque required to rotate at least one of the two motors when the two motors are rotated in synchronization is detected.

  According to the fuel cell system described above, the rotational torque of at least one motor is detected by the rotational control rotational torque detecting means in a situation where the required power generation amount for the fuel cell is small, is 0, or the fluctuation of the required power generation amount hardly occurs. Can be detected. For this reason, the detection accuracy of the rotational torque of the motor can be effectively increased, and the energy consumption for driving the motor can be reduced more effectively. In addition, it is possible to suppress a decrease in the merchantability of a fuel cell vehicle using the fuel cell system.

  Further, in the fuel cell system according to the present invention, preferably, the fuel cell system is mounted on a vehicle and used as a vehicle-mounted fuel cell system that supplies electric power directly or via a power storage unit to a traveling motor that is a driving source of the vehicle. Further, the rotation control rotational torque detection means causes the vehicle motor to continuously idle at a constant speed when the vehicle stops running, or to cause the fuel cell to generate power in an idle operation state in which the load of the fuel cell is unlikely to fluctuate. Or, when an idle operation command signal that instructs not to extract regenerative power from the traveling motor even if the vehicle is decelerated during traveling of the vehicle is input, one of the two motors is rotated or stopped at a constant speed. At the same time, after accelerating or decelerating the other motor, at least one of the two motors in the case of rotating the two motors synchronously. Detecting the rotational torque required to rotate the motor.

  According to the fuel cell system described above, the rotational torque of at least one motor is detected by the rotational control rotational torque detecting means in a situation where the required power generation amount for the fuel cell is small, is 0, or the fluctuation of the required power generation amount hardly occurs. Can be detected. For this reason, the detection accuracy of the rotational torque of the motor can be effectively increased, and the energy consumption for driving the motor can be reduced more effectively. In addition, it is possible to suppress a decrease in the merchantability of a fuel cell vehicle using the fuel cell system.

  Further, in the fuel cell system according to the present invention, preferably, the fuel cell system is mounted on a vehicle and used as a vehicle-mounted fuel cell system that supplies electric power directly or via a power storage unit to a traveling motor that is a driving source of the vehicle. Further, the rotation control rotational torque detection means stops the power generation operation of the fuel cell from the vehicle side when the required power generation amount required for the fuel cell is equal to or less than a predetermined value that is set in advance and exceeds the predetermined value again. When a power generation stop command signal instructed to stop the power generation operation of the fuel cell is input in the intermittent mode for restarting the power generation operation, one of the two motors is rotated or stopped at a constant speed. At the same time, after accelerating or decelerating the other motor, rotate at least one of the two motors when rotating the two motors synchronously. Detecting the rotational torque required to that.

  According to the fuel cell system described above, the rotational torque of at least one motor is detected by the rotational control rotational torque detecting means in a situation where the required power generation amount for the fuel cell is small, is 0, or the fluctuation of the required power generation amount hardly occurs. Can be detected. For this reason, the detection accuracy of the rotational torque of the motor can be effectively increased, and the energy consumption for driving the motor can be reduced more effectively. In addition, it is possible to suppress a decrease in the merchantability of a fuel cell vehicle using the fuel cell system.

  In the fuel cell system according to the present invention, preferably, a discharge flow path for discharging the fuel gas-based gas from the fuel cell, and a circulation for returning the fuel gas-based gas discharged from the fuel cell to the fuel cell. And a discharge valve provided in the exhaust drainage channel connected to the discharge channel, and the pressurizing pump is provided in the circulation channel and pressurizes and discharges the fuel gas system gas as the reaction gas The rotation control rotation torque detecting means opens the discharge valve when the fuel cell power generation operation is stopped, and performs a scavenging process in which the pressure pump is continuously driven for a predetermined time. When one motor is rotated or stopped at a constant speed, and at the same time the other motor is accelerated or decelerated, at least one of the two motors in the case of rotating the two motors synchronously is rotated. Detecting the rotational torque required.

  According to the fuel cell system described above, the rotational torque of at least one motor can be detected by the rotational control rotational torque detecting means in a situation where it is not required to vary the pressure applied by the pressure pump from the aspect of the scavenging process. For this reason, the detection accuracy of the rotational torque of the motor can be effectively increased, and the energy consumption for driving the motor can be reduced more effectively. Moreover, since the motor is driven at a high speed for a long time, the thermal expansion of the components of the pressure pump tends to reduce the gap between the two rotors and between the rotor and the casing, and the two motors are appropriate. It becomes easy to obtain a precise phase difference with higher accuracy.

  According to the fuel cell system of the present invention, as a result, when a biaxial rotary pump such as a Roots pump is used as a pressurizing pump that pressurizes and discharges the reaction gas, the inconvenience due to oil can be eliminated. , Improvement of mountability can be achieved.

  Hereinafter, an example of an embodiment according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a basic configuration diagram of a fuel cell vehicle equipped with a fuel cell system according to an embodiment of the present invention. FIG. 2 is a basic configuration diagram of the fuel cell system of the present embodiment. FIG. 3 is a schematic cross-sectional view showing the hydrogen pump shown in FIG. FIG. 4 is a schematic cross-sectional view taken along the line AA of FIG. FIG. 5 is a flowchart illustrating an optimal condition motor drive control method in which two motors are rotated in synchronization with each other under the condition that the rotational torque of the motor is minimized in the present embodiment. FIG. 6 is a diagram illustrating an example of a relationship between a virtual phase difference between two motors constituting a hydrogen pump and a detected value of rotational torque of one motor in the present embodiment. FIG. 7 is a schematic diagram of an example of a conventional hydrogen pump for a fuel cell system.

  As shown in FIG. 1, a fuel cell vehicle 10 that is a vehicle equipped with a fuel cell has a fuel cell stack (FC) 12 that is a fuel cell and a battery 14 that is a power storage unit and a secondary battery on the front side of the vehicle. It is installed. By connecting the fuel cell stack 12 and the battery 14, the battery 14 is charged by supplying the power generated by the fuel cell stack 12 to the battery 14. Further, a battery 14 and a fuel cell stack 12 and two traveling motors 16 that are vehicle drive sources provided on both sides of the vehicle in the left-right direction (vertical direction in FIG. 1) are connected to a boost converter and an inverter (not shown). The electric power from the battery 14 or the fuel cell stack 12 can be supplied to each traveling motor 16. The rotating shaft of each traveling motor 16 is coupled to the wheel 18 via a clutch mechanism (not shown), and the wheel 18 is driven by the driving of each traveling motor 16. It is also possible to supply power from the fuel cell stack 12 to each traveling motor 16 via the battery 14 without connecting the fuel cell stack 12 and each traveling motor 16.

  The fuel cell vehicle 10 is provided with only one traveling motor 16, and power is transmitted between the traveling motor 16 and an axle (not shown) that drives the two wheels 18 via a power transmission mechanism including a clutch mechanism. It can also be combined. In this case, electric power can be supplied from the battery 14 to one traveling motor 16. In the present embodiment, the above clutch mechanism can be omitted. The fuel cell system according to the present invention is not limited to the one mounted on the fuel cell vehicle 10, and can be used for other purposes.

  Next, a fuel cell system including the fuel cell stack 12 will be described. As shown in FIG. 2, the fuel cell system 20 includes a fuel cell stack 12 and a control unit 22. The fuel cell stack 12 has a plurality of fuel cells stacked, and a current collector plate and an end plate are provided at both ends of the fuel cell stack 12 in the stacking direction. Then, the plurality of fuel cells, the current collector plate, and the end plate are fastened with tie rods, nuts, and the like. An insulating plate can also be provided between the current collector plate and the end plate.

Although a detailed view of each fuel cell is omitted, it is assumed that, for example, a membrane assembly in which an electrolyte membrane is sandwiched between an anode electrode and a cathode electrode and separators on both sides thereof are provided. Further, fuel gas is supplied to the anode electrode (hereinafter simply referred to as “anode”), and hydrogen gas that is a hydrogen-containing gas can be supplied, and oxidizing gas is supplied to the cathode side electrode (hereinafter simply referred to as “cathode”). It is possible to supply air. Then, hydrogen ions generated by the catalytic reaction at the anode, that is, proton H ⁺ are moved to the cathode through the electrolyte membrane, and water is generated by causing an electrochemical reaction with oxygen at the cathode. Also, an electromotive force is generated by moving electrons from the anode to the cathode through an external circuit. That is, the fuel cell stack 12 in which a plurality of fuel cells shown in FIG. 1 are stacked generates power by an electrochemical reaction between an oxidizing gas and a fuel gas, which are reaction gases.

  The fuel cell system 20 supplies air to the fuel cell stack 12, and is an air after being subjected to an electrochemical reaction from the fuel cell stack 12, and an oxidizing gas path for discharging an air off-gas that is an oxidizing gas-based gas 24 and a fuel gas path 26 for discharging a hydrogen off-gas, which is a hydrogen gas after being supplied to the fuel cell stack 12 and subjected to an electrochemical reaction from the fuel cell stack 12 and being a fuel gas-based gas. With. The oxidizing gas path 24 includes an oxidizing gas supply flow path 28 for supplying air to the fuel cell stack 12 and an oxidizing gas system discharge flow path 30 for discharging air off-gas from the fuel cell stack 12. An air compressor 32 is provided upstream of the oxidizing gas supply channel 28. The air pressurized by the air compressor 32 is humidified by the humidifier 34 and then supplied to the oxidizing gas passage on the cathode side of the fuel cell stack 12.

  The air off-gas supplied to the fuel cell stack 12 and subjected to an electrochemical reaction in each fuel cell is discharged from the fuel cell stack 12 through the oxidizing gas system discharge flow path 30 and then passes through the humidifier 34. Then, it is discharged to the atmosphere via a pressure control valve (not shown). The humidifier 34 serves to humidify the moisture obtained from the air off-gas discharged from the fuel cell stack 12 to the air before being supplied to the fuel cell stack 12.

  The fuel gas path 26 includes a fuel gas supply flow path 38 for supplying hydrogen gas to the fuel cell stack 12, a fuel gas system discharge flow path 40 for discharging hydrogen off-gas from the fuel cell stack 12, and a fuel. A gas circulation path 42. The hydrogen off gas includes unreacted hydrogen. A hydrogen gas supply device (not shown) such as a high-pressure hydrogen tank, which is a fuel gas supply device, is provided upstream of the fuel gas supply flow path 38. Then, hydrogen gas is supplied from the hydrogen gas supply device to the fuel cell stack 12 through a fuel gas supply valve 44 that is an electromagnetic valve.

  The hydrogen off-gas supplied to the anode-side fuel gas internal flow path provided in the fuel cell stack 12 and subjected to the electrochemical reaction is discharged from the fuel cell stack 12 through the fuel gas system discharge flow path 40. The fuel gas circulation path 42 is provided for returning the hydrogen off-gas containing unreacted hydrogen gas discharged from the fuel cell stack 12 to the fuel gas supply path 38 and returning it to the fuel cell stack 12. .

  The fuel gas circulation passage 42 is provided with a hydrogen pump 46 that is a fuel gas circulation pump and a pressurizing pump. The hydrogen pump 46 returns the hydrogen off gas to the fuel gas supply flow path 38 through the fuel gas system circulation flow path 42, merges with the new hydrogen gas sent from the hydrogen gas supply device, and then supplies the hydrogen off gas to the fuel cell stack 12 again. To do. The hydrogen pump 46 is connected to the battery 14 (FIG. 1) and the fuel cell stack 12, and is driven by being supplied with electric power from the fuel cell stack 12 via the battery 14 or not via the battery 14. The hydrogen pump 46 can adjust the rotation speed.

  A purge valve 50, which is an electromagnetic valve and is a discharge valve, is provided in the exhaust / drain passage 48 connected to the gas downstream end of the fuel gas system discharge passage 40. The gas and moisture sent to the gas downstream side through a gas-liquid separator (not shown) provided at the connection between the fuel gas system discharge flow path 40 and the exhaust drainage flow path 48 are converted into the oxidizing gas system discharge flow path 30. The air off-gas sent through the air is combined with a diluter (not shown) so that the hydrogen concentration is sufficiently lowered and then discharged to the outside.

  Further, the air compressor 32, the hydrogen pump 46, the fuel gas supply valve 44, and the purge valve 50 are each connected to the control unit 22. The control unit 22 is called an ECU, and outputs a control signal for controlling driving to the air compressor 32 and the hydrogen pump 46, and outputs a control signal for controlling the opening and closing of the fuel gas supply valve 44 and the purge valve 50. To do. The control unit 22 includes motor drive control means 52, rotation control rotation torque detection means 54, and optimum condition motor drive control means 56.

  The control unit 22 is connected to a start switch (not shown) that functions as an ignition switch of the fuel cell system 20, on condition that a power generation start signal corresponding to an ON state, that is, a fuel cell start command signal is received from the start switch. The power generation operation stop process is executed on condition that the power generation start process is executed and a power generation stop signal corresponding to the off state is received.

  The controller 22 rotates the air compressor 32 and opens the fuel gas supply valve 44 when the power generation start process is executed and during normal operation of the fuel cell stack 12, and the oxidizing gas supply flow to the fuel cell stack 12. Air is supplied through the passage 28 and hydrogen gas is also supplied through the fuel gas supply passage 38. Further, the motor drive control means 52 drives two motors 58 and 60 (FIG. 3), which will be described later, provided in the hydrogen pump 46 during normal operation.

  In addition, the control unit 22 stops (turns off) the rotational drive of the air compressor 32 on condition that a power generation operation stop command for the fuel cell stack 12 corresponding to turning off of the start switch, that is, a start stop command signal is received. ) The function of stopping the pressurized supply of air from the air compressor 32 to the fuel cell stack 12 and closing the fuel gas supply valve 44 to stop the supply of hydrogen gas from the hydrogen gas supply device to the fuel cell stack 12. Have Further, the control unit 22 stops (turns off) the rotation drive of the hydrogen pump 46 on the condition that the power generation operation stop command is received, and the fuel gas supply flow from the fuel gas system circulation passage 42 by the hydrogen pump 46. It has a function of stopping the reflux of hydrogen gas to the passage 38.

  Further, when receiving the power generation operation stop command for the fuel cell stack 12, the control unit 22 stops the rotation drive of the air compressor 32 and before stopping the rotation drive of the hydrogen pump 46. Further, it also has a function of controlling opening / closing of the purge valve 50 and driving of the hydrogen pump 46 and the air compressor 32 so as to perform a scavenging process for purging residual moisture from the gas. That is, when the scavenging process is performed, the control unit 22 opens the purge valve 50 when the power generation operation of the fuel cell stack 12 is stopped, and the air compressor 32 and the hydrogen pump 46 are set in advance respectively. The purge valve 50 is continuously driven at a constant speed, i.e., at a constant rotational speed, to scavenge, i.e. remove, residual moisture in the cathode-side channel and the anode-side channel of the fuel cell stack 12. The opening and closing and the driving of the air compressor 32 and the hydrogen pump 46 are controlled.

  Next, the configuration of the hydrogen pump 46, which is a pressurizing pump, will be described in detail with reference to FIGS. As shown in FIGS. 3 and 4, the hydrogen pump 46 is a volume compression type Roots pump type that is a biaxial rotary pump, and pressurizes the hydrogen off-gas supplied from the suction port 62 (FIG. 4). Then, the ink is discharged through the discharge port 64 (FIG. 4). That is, the hydrogen pump 46 includes two rotor rotating shafts 68 and 70 that are rotatably provided in the casing 66 in parallel with each other, that is, are rotatably supported, and two that each have an outer peripheral surface that is a non-cylindrical surface. , And a suction port 62, a discharge port 64, and two motors 58 and 60. The two saddle-shaped rotors 72 and 74 are provided in a state of being fixed to the outer diameter side of the two rotor rotating shafts 68 and 70, and the two saddle-shaped rotors 72 and 74 are opposed to each other.

  As shown in FIG. 4, the suction port 62 and the discharge port 64 are respectively provided on the opposite sides of the casing 66. The suction port 62 takes in hydrogen off gas into the casing 66, and the discharge port 64 sends out hydrogen off gas from inside the casing 66. Returning to FIG. 3, the two motors are provided outside the casing 66. That is, the motor cases 76 and 78 constituting the two motors 58 and 60 are fixed on both sides of the casing 66, that is, on the opposite side through the casing 66. Each of the motors 58 and 60 is fixed to a motor rotor 80 provided in a portion of the rotor rotating shafts 68 and 70 located inside the motor cases 76 and 78, and fixed inside the motor cases 76 and 78. And an opposing motor stator 82. Each of the motors 58 and 60 is, for example, a three-phase AC motor, and is a permanent magnet type synchronous motor, a reluctance motor, an induction motor, or the like.

  A part of each rotor rotating shaft 68, 70 is inserted into the casing 66. As shown in FIG. 4, a columnar rotor space 84 having a substantially elliptical cross section is provided in the casing 66. The two saddle-shaped rotors 72 and 74 are fixed to portions of the rotor rotation shafts 68 and 70 located in the rotor space 84. That is, the two saddle-shaped rotors 72 and 74 are fixed on the outer diameter side of the rotor rotation shafts 68 and 70 while maintaining a mutual phase difference at a preset predetermined angle such as 90 degrees. The both rotors 72 and 74 are opposed to each other. In addition, motor drive shafts 86 and 88 that constitute the motors 58 and 60 are configured by a part of the rotor rotation shafts 68 and 70 that are located in the motor cases 76 and 78 shown in FIG. Yes.

  As shown by arrows α and β in FIG. 4, the two motors 58 and 60 (FIG. 3) rotate in opposite directions. Throughout this specification, “the phase difference between the two motors 58 and 60” refers to the axial direction of the rotor rotation shafts 68 and 70 including the motor drive shafts 86 and 88 (FIG. 3), as shown in FIG. When viewed in one direction, between the phases θ2 and θ1 of the rotor rotation shafts 68 and 70 that increase with each rotation with respect to parallel reference planes S1 and S2 passing through the rotor rotation shafts 68 and 70, respectively. FIG. 4 shows, for example, (θ2−θ1).

  Further, the two rotor rotating shafts 68 and 70 are not coupled with two gears that mesh with each other to synchronize their rotations. That is, in the present embodiment, there is no gear such as a timing gear for synchronously rotating the two rotor rotating shafts 68 and 70. Further, when the phase relationship between the two rotor rotation shafts 68 and 70 changes, the rotational torque required to rotate the motors 58 and 60 changes. In addition, when the phase difference that is the phase relationship between the two rotor rotating shafts 68 and 70 deviates excessively from the appropriate phase difference, the two saddle-shaped rotors 72 and 74 collide strongly. Therefore, there is a possibility that the hydrogen pump 46 cannot function normally. For this reason, it is necessary to regulate the phase relationship between the two rotor rotating shafts 68 and 70.

  As shown in FIG. 2, the driving of the hydrogen pump 46 is controlled by the control unit 22. That is, the motor drive control means included in the control unit 22 controls the rotational drive of the motors 58 and 60 so that the two motors 58 and 60 (FIG. 3) are rotated in the reverse direction in synchronization.

  Further, in the present embodiment, as shown in FIG. 3, gears that engage each other such as timing gears are not coupled to the rotor rotation shafts 68 and 70 including the motor drive shafts 86 and 88 of the two motors 58 and 60. Nevertheless, the two motors 58 and 60 can be driven to rotate synchronously with an appropriate phase difference. For this reason, the two motors 58 and 60 are synchronized in the reverse direction under the condition that the rotational torque required to rotate at least one of the two motors 58 and 60 is minimized. It is designed to be driven to rotate.

  More specifically, the rotation control rotational torque detecting means 54 of the control unit 22 shown in FIG. 2 is the same as one of the two motors 58 and 60 shown in FIG. 3 (or 60, hereinafter the same). ) Is rotated or stopped at a constant speed, and at the same time the other motor 60 (or 50, the same applies hereinafter) is accelerated or decelerated, and then the two motors 58 and 60 are rotated in the opposite direction in synchronization with each other. The rotational torque required to rotate at least one motor 58 (or 60) of the two motors 58 and 60 is detected.

  Further, the optimum condition motor drive control means 56 shown in FIG. 2 is such that the detected rotational torque of at least one motor 58 (or 60) of the two motors 58 and 60 shown in FIG. Thus, the drive of the two motors 58 and 60 is controlled so that the two motors 58 and 60 rotate in synchronization. That is, when the two saddle-shaped rotors 72 and 74 slide on each other at the time of rotation or are strongly pressed against each other by thermal expansion, the necessary rotational torque required to rotate the two motors 58 and 60 is obtained. It can grow. The required rotational torque increases as the amount of deviation increases when the phase difference between the two motors 58 and 60 deviates from an appropriate phase difference, for example, 90 degrees. In the present embodiment, paying attention to such a phenomenon, the two motors 58 and 60 are rotated in synchronization with each other under the condition that the required rotational torque is minimized, so that the two rotor rotating shafts 68 are rotated. , 70, the two motors 58, 60 can be driven to rotate synchronously with an appropriate phase difference, although the gears such as timing gears are not coupled to each other.

  Specifically, an optimum condition motor drive control method is performed in which the motors 58 and 60 are rotated in synchronization with each other under the condition that the required rotational torque of the motors 58 and 60 is minimized as follows. In the following description, the same elements as those shown in FIGS. 1 to 4 are denoted by the same reference numerals. As shown in FIG. 5, first, in step S1, the rotation control rotational torque detecting means 54 determines whether or not a precondition for performing optimal condition motor drive control is satisfied, and it is determined that it is satisfied. If so, the process proceeds to step S2. The precondition is a condition that is set in advance and stored in the storage unit, for example, when the power generation operation of the fuel cell stack 12 is stopped, or torque with respect to the traveling motor 16 that is a load connected to the fuel cell stack 12 Assume that the command is constant. Further, the precondition is that the fuel cell start command signal, the fuel cell start / stop command signal from the vehicle side, the traveling motor 16 is kept at a constant speed when the vehicle is stopped, and is kept idle by disengaging the clutch mechanism, or the fuel cell stack An idle operation command signal for instructing that the fuel cell stack 12 generate electric power in an idle operation state in which the load of 12 is less likely to fluctuate, or that no regenerative power is taken out from the traveling motor 16 even if the vehicle is decelerated during traveling. In the intermittent mode in which the power generation operation of the fuel cell stack 12 is stopped when the required power generation amount required for the stack 12 is equal to or less than a predetermined value set in advance, and the power generation operation is resumed when the required power generation amount exceeds the predetermined value again. Any one of the power generation stop command signals during the intermittent mode instructing to stop the power generation operation of the fuel cell stack 12 It is also possible to be entered. Further, the precondition may be that after the fuel cell activation command signal is input from the vehicle side, before the acceleration command of the traveling motor 16 by the depression of the accelerator pedal is input.

  In any case, if the precondition is satisfied, the process proceeds to the acceleration detection process in step S2. Next, in step S3, the rotation control rotational torque detecting means 54 is in a state where one motor 58 of the two motors 58, 60 is rotated at a constant speed or stopped at a predetermined time A. The motor 60 is accelerated at a preset constant acceleration. For example, when two motors 58 and 60 are rotated at a rotation speed of 500 rotations / second, the rotation speed of one motor 58 is set to 500 rotations / second, and the other motor 60 is rotated 501 hours A. After accelerating to / sec, the rotational speed of the other motor 60 is returned to 500 rpm. As a result, the phase difference between the two motors 58 and 60 deviates from the initial state. For example, when it is assumed that the phase difference between the two motors 58 and 60 is 90 degrees in the initial state, θ1 increases after acceleration of the other motor 60, so that the assumed virtual phase difference is θ2−θ1 becomes small, for example, shifts to 89 degrees or the like.

  Next, in step S4 of FIG. 5, the rotation control rotational torque detecting means 54 detects the rotational torque necessary to rotate one motor 58 (or 60, the same applies hereinafter), and the detected value is assumed to be the current assumption. The information is stored in the storage unit included in the control unit 22 in association with the virtual phase difference. For example, the rotational torque of one motor 58 necessary to keep one motor 58 rotating at a predetermined rotational speed, for example, 500 revolutions / second is detected, and the detected value of the detected rotational torque is stored in the storage unit. Are stored in association with the assumed virtual phase difference.

  Next, in step S5 of FIG. 5, it is determined whether or not the acceleration detection process from S2 to S4 has been repeated N times a predetermined number of times. If this determination result is negative, the determination result is determined in step S5. Steps S2 to S5 are repeated until affirmative. Further, since the other motor 60 is accelerated in each acceleration detection process, the virtual phase difference between the two motors 58 and 60 is reduced according to the number of acceleration detection processes.

  If it is determined in step S5 in FIG. 5 that the acceleration detection process has been repeated N times, in step S6, the rotation control rotational torque detecting means 54 sets the phase difference between the two motors 58 and 60 to the initial value, that is, the first time. The driving of the two motors 58 and 60 is controlled so as to accelerate or decelerate one of the two motors 58 and 60 so that the virtual phase difference before the acceleration detection process is performed, for example, 90 degrees.

  Next, the process proceeds to a deceleration detection process in step S7, and in step S8, the rotation control rotation torque detection means 54 rotates one of the two motors 58, 60 at a constant speed for a predetermined time A. Alternatively, with the rotation stopped, the other motor 60 is decelerated at a preset constant acceleration. For example, when two motors 58 and 60 are rotated at a rotation speed of 500 rotations / second, the rotation speed of one motor 58 is kept at 500 rotations / second, and the other motor 60 is rotated for 499 rotations per hour. After decelerating to / sec, the rotational speed of the other motor 60 is returned to 500 rpm. As a result, the virtual phase difference between the two motors 58 and 60 deviates from the initial state. For example, when it is assumed that the virtual phase difference between the two motors 58 and 60 is 90 degrees in the initial state, θ1 becomes smaller after the deceleration of the other motor 60, so that the assumed virtual phase difference is , Θ2−θ1 increases, and shifts to 91 degrees, for example.

  Next, in step S9 of FIG. 5, the rotation control rotational torque detecting means 54 detects the rotational torque necessary to rotate one motor 58, and associates the detected value with the currently assumed virtual phase difference. And stored in a storage unit included in the control unit 22. For example, the rotational torque of one motor 58 necessary to keep one motor 58 rotating at a predetermined rotational speed, for example, 500 revolutions / second is detected, and the detected value of the detected rotational torque is stored in the storage unit. Are stored in association with the assumed virtual phase difference.

  Next, in step S10 in FIG. 5, it is determined whether or not the deceleration detection process from S7 to S9 has been repeated a predetermined number of times N times. If the determination result is negative, the determination result is in step S10. Steps S7 to S10 are repeated until affirmative. In addition, since the other motor 60 is decelerated in each deceleration detection process, the virtual phase difference between the two motors 58 and 60 increases according to the number of deceleration detection processes.

  If it is determined in step S10 in FIG. 5 that the deceleration detection process has been repeated N times, in step S11, the optimum condition motor drive control unit 56 determines that the detected values of the plurality of detected rotational torques are minimum. Is calculated. For example, FIG. 6 shows an example of the relationship between the detected rotational torque of one motor 58 and the virtual phase difference, and the rotational torque of one motor 58 is minimized by the virtual phase difference γ. . In this case, the optimum condition motor drive control means 56 calculates γ as a virtual phase difference for detecting the minimum torque. Note that the rotation torque of the motor 58 that is the smallest in the virtual phase difference γ corresponds to a dead zone due to the generation of a gap between the two saddle-shaped rotors 72 and 74.

  Next, in step S12 of FIG. 5, the optimum condition motor drive control means 56 rotates the two motors 58 and 60 in the reverse direction in a state set to the same condition as that at which the minimum rotational torque is detected. The drive of both motors 58 and 60 is controlled so as to drive. Specifically, in order to match the condition of the virtual phase difference γ, the other motor 60 of the two motors 58 and 60 is rotated or stopped at a constant speed for a predetermined time A, and at the same time, The motor 58 is decelerated at a predetermined constant deceleration, and this process is repeated until the virtual phase difference between the two motors becomes γ. As a result, the phase difference condition between the two motors 58 and 60 is set as the minimum rotational torque detection condition. Therefore, for example, when the virtual phase difference between the two motors 58 and 60 is 90 degrees and the rotational resistance of the motors 58 and 60 is minimized, the rotation control is performed even when the virtual phase difference is deviated from 90 degrees. The rotational phase detector 54 and the optimum condition motor drive controller 56 can automatically correct the virtual phase difference between the two motors 58 and 60 to 90 degrees, which is an appropriate phase difference. Note that whether or not the virtual phase difference matches the actual phase difference depends on whether or not the virtual phase difference in the initial state matches the actual phase difference in the initial state, but according to the present embodiment, The two motors 58 and 60 can be driven synchronously with the phase difference between the two motors 58 and 60 automatically corrected so as to minimize the rotational torque without detecting the actual accurate phase difference. .

  Further, depending on the shape of the saddle-shaped rotors 72 and 74, the rotational torque may be minimized when the phase difference between the two motors 58 and 60 is other than 90 degrees, for example, 87 degrees. The control means 56 can correct the phase difference between the two motors 58 and 60 to a phase difference of, for example, 87 degrees that minimizes the rotational torque. In addition, the phase difference between the two motors 58 and 60 can be shifted by a predetermined angle such as 0.1 degrees, for example, and a detection value of rotational torque corresponding to the shifted phase difference can be obtained. .

  Further, the rotation control rotational torque detecting means 54 stops one motor 58 of the two motors 58, 60 and simultaneously accelerates the other motor 60, thereby shifting the virtual phase difference and It is also possible to detect a rotational torque necessary to rotate at least one of the two motors when the motors are rotated synchronously. Further, in the optimum condition motor drive control method shown in FIG. 5, the acceleration detection process may be performed after the deceleration detection process instead of performing the deceleration detection process after the acceleration detection process. In the optimum condition motor drive control method shown in FIG. 5, when the rotation control rotation torque detection means 54 performs the acceleration detection process or the deceleration detection process a plurality of times, the optimum condition motor drive control means 56 When the detected rotational torque stored in the current acceleration detection process or the deceleration detection process is larger than the detected rotational torque stored in the detection process or the deceleration detection process, the phase difference between the two motors 58 and 60 is set to the previous value. The drive of the two motors 58 and 60 can be feedback controlled so as to correct the virtual phase difference. In this case, the rotation control rotation torque detection means 54 performs a plurality of times of deceleration detection processing or acceleration detection processing different from the previous time after being corrected to the previous virtual phase difference, and the optimum condition motor drive control means 56 When the detected rotational torque stored in the current deceleration detection process or acceleration detection process becomes larger than the detected rotational torque stored in the previous deceleration detection process or acceleration detection process during the detection process, the two motors 58 , 60 is corrected to the previous virtual phase difference, so that the two motors 58, 60 are synchronized under the optimum condition in which the detected rotational torque of one motor 58 (or 60) is minimized. The drive of the two motors 58 and 60 is controlled so as to rotate.

  Note that the precondition in step S1 of FIG. 5 is that the purge valve 50 is opened when the power generation operation of the fuel cell stack 12 is stopped, and the scavenging process continues to drive the hydrogen pump 46 for a predetermined time. You can also. That is, the rotation control rotation torque detecting means 54 rotates or stops one motor 58 (or the other motor 60) of the two motors 58, 60 at a constant speed at the same time as the other motor 60 ( Alternatively, the rotational resistance of at least one motor 58 (or 60) of the two motors 58 and 60 when the two motors 58 and 60 are rotated synchronously after the one motor 58) is accelerated or decelerated. Alternatively, the rotational torque can be detected.

  According to such a fuel cell system of the present embodiment, the motors of the two motors 58 and 60 are driven by a part of the two rotor rotating shafts 68 and 70 provided with the two saddle-shaped rotors 72 and 74. Since the shafts 86 and 88 are configured, the two rotor rotating shafts 68 and 70 can be rotationally driven by the two motors 58 and 60 without using a gear mechanism. Therefore, unlike the case where the two rotor rotating shafts 68 and 70 are rotated by one motor 58 and 60, a gear having a gear such as a timing gear that meshes with the two rotor rotating shafts 68 and 70 with a large force. There is no need to provide a mechanism. Therefore, it is not necessary to use oil for lubricating the gear, oil flows into the fuel cell, sliding resistance is generated by the oil seal, and the cost required for maintenance and inspection of the fuel cell system 20 increases. It is possible to effectively prevent inconvenience caused by oil.

  Further, since each motor 58, 60 only needs to drive two rotor rotation shafts 68, 70 that are different from each other, each motor 58, 60 can be reduced in size, and the roots can be reduced. It is possible to improve the degree of freedom in installing the hydrogen pump 46 with respect to the installation space of the hydrogen pump 46 that is a type pump. As a result, when a roots type pump is used for the hydrogen pump 46 that pressurizes and discharges the hydrogen off-gas, inconveniences caused by oil can be eliminated, and mountability can be improved.

  On the other hand, FIG. 7 shows a schematic diagram of an example of a hydrogen pump for a fuel cell system, which has been conventionally considered, for explaining inconvenience due to a configuration deviating from the present invention. A conventional hydrogen pump 46a shown in FIG. 7 is a Roots-type pump, and two motors 72 and 74 are rotatably arranged in a casing (not shown), and a motor drive that constitutes one motor 92 is provided. One saddle-shaped rotor 72, 74 is fixed to a portion of the shaft 94 protruding into the casing, and the motor drive shaft 94 is placed in a casing or a motor case (not shown) constituting the motor 92 by two bearings 96. It is rotatably supported. Further, the driven shaft 98 is rotatably supported by the bearing 96 in the casing. The two gears 100 and 102 which are timing gears are fixed to the driven shaft 98 and the motor drive shaft 94, and the two gears 100 and 102 are engaged with each other.

  Seal members 104 are provided between the motor drive shaft 94 and the motor case or casing, and between the driven shaft 98 and the casing, respectively, and the oil sealed in the gears 100 and 102 for lubrication is a saddle-shaped rotor 72. 74, and prevents leakage to the outside. In the case of such a conventional hydrogen pump 46a, for example, a torque of 50% is transmitted from one motor 92 to the two saddle rotors 72 and 74. In the case of such a conventional hydrogen pump 46a, oil is required, so the seal member 104 is necessary, and the rotational resistance of the motor 92 may increase due to the sliding resistance of the seal member 104. Inconvenience due to oil may occur. On the other hand, according to the present embodiment, as shown in FIGS. 3 and 4, since it is not necessary to use oil for the hydrogen pump 46, the rotational resistance of the motors 58 and 60 can be reduced. Inconvenience caused by oil can be eliminated.

  Further, in the present embodiment, the two rotor rotating shafts 68 and 70 are not coupled with two gears that mesh with each other to synchronize their rotations, so the gears can be eliminated in the fuel cell system 20. Can or less.

  In addition, since the two motors 58 and 60 are provided on both sides of the casing 66, heat generated by the rotation of the two motors 58 and 60 from both sides of the casing 66 is generated in the components in the casing 66. It becomes easy to transmit efficiently and almost uniformly. For this reason, as in the present embodiment, the fuel cell system 20 is mounted on a vehicle, and is used for mounting the fuel cell vehicle 10 that supplies electric power directly or via the battery 14 to the traveling motor 16 that is a driving source of the vehicle. Even when the fuel cell vehicle 10 is used in a low temperature environment such as below freezing, the components of the hydrogen pump 46, which is a roots type pump, can be effectively prevented from freezing, and the fuel cell system 20 can be operated or restarted. It becomes easy to perform effectively.

  Further, the heat generated by the motors 58 and 60 is transmitted, that is, dissipated, to other components such as components in the casing 66 through the rotor rotation shafts 68 and 70 including the motor drive shafts 86 and 88. On the other hand, by using two motors 58 and 60 for the hydrogen pump 46 as in the present embodiment, the area of the heat transfer portion that can effectively transfer heat from the motors 58 and 60 is increased. The output of the motors 58 and 60 can be easily improved effectively.

  Further, the control unit 22 rotates or stops one motor 58 (or 60) of the two motors 58 and 60 at a constant speed and simultaneously accelerates or decelerates the other motor 60 (or 58). Rotation control rotational torque detection for detecting rotational torque required to rotate at least one motor 58 (or 60) of the two motors 58, 60 when the two motors 58, 60 are rotated synchronously The two motors 58 and 60 are rotated in synchronism with each other under the optimum condition that the detected rotational torque of the means 54 and at least one motor 58 (or 60) of the two motors 58 and 60 is minimized. And optimal condition motor drive control means 56 for controlling the drive of the two motors 58 and 60. Therefore, even when the phase difference between the two motors 58 and 60 deviates from the appropriate phase difference at which the rotational torque of the two motors 58 and 60 is minimized, the phase difference between the two motors 58 and 60 is set appropriately. The phase difference can be corrected, and energy consumption for driving the motors 58 and 60 can be reduced. In this case, when the hydrogen pump 46 is assembled, there is no need to perform a process of assembling the two motors 58 and 60 with the phase difference set with high accuracy. That is, it is not necessary to set the phase difference between the two motors 58 and 60 with high accuracy at the time of assembly, and the phase difference may be corrected to an appropriate phase difference at the start of use after assembly.

  Further, the rotation control rotational torque detecting means 54 has two pieces of torque command when the fuel cell stack 12 stops the power generation operation or when the torque command to the traveling motor 16 that is a load connected to the fuel cell stack 12 is constant. One motor 58 (or 60) of the motors 58 and 60 is rotated or stopped at a constant speed, and at the same time, the other motor 58 (or 60) is accelerated or decelerated, and then the two motors 58 and 60 are synchronized. Rotational torque required to rotate at least one motor 58 (or 60) of the two motors 58 and 60 when rotating the motor is detected. Therefore, the rotational torque of at least one motor 58 (or 60) is detected by the rotational control rotational torque detecting means 54 in a situation where the required power generation amount for the fuel cell stack 12 is small or the fluctuation of the required power generation amount hardly occurs. it can. For this reason, the detection accuracy of the rotational torque of the motors 58 and 60 can be effectively increased, and the energy consumption for driving the motors 58 and 60 can be reduced more effectively. In addition, it is possible to suppress a decrease in the merchantability of the fuel cell vehicle 10 that is a product that uses the fuel cell system 20.

  The fuel cell system 20 is mounted on a vehicle and used as a vehicle-mounted fuel cell system that supplies electric power directly or via a battery 14 to a travel motor 16 that is a vehicle drive source. The torque detection means 54 keeps the fuel cell start command signal, the fuel cell start / stop command signal from the vehicle side, keeps the traveling motor 16 idling at a constant speed when the vehicle stops traveling, or the load of the fuel cell stack 12 fluctuates. Even when the fuel cell stack 12 is caused to generate power in a difficult idle operation state, or even when the vehicle is decelerated, the regenerative electric power is not taken out from the travel motor 16, that is, the travel motor 16 does not generate power, and the travel motor 16 is simply The idle operation command signal for instructing the rotation and the required power generation amount required for the fuel cell stack 12 are set in advance. The intermittent mode instructing to stop the power generation operation of the fuel cell stack 12 in the intermittent mode in which the power generation operation of the fuel cell stack 12 is stopped when the predetermined value or less is exceeded and the power generation operation is resumed when the predetermined value is exceeded again. When any one of the intermediate power generation stop command signals is input, one motor 58 (or 60) of the two motors 58 and 60 is rotated or stopped at a constant speed, and at the same time, the other motor 60 (or 58). ) Is required to rotate at least one motor 58 (or 60) of the two motors 58 and 60 when the two motors 58 and 60 are rotated synchronously after acceleration or deceleration. It can also be configured to detect torque. In the case of this configuration, at least one motor 58 is detected by the rotation control rotation torque detecting means 54 in a situation where the required power generation amount for the fuel cell stack 12 is small, zero, or fluctuation of the required power generation amount hardly occurs. (Or 60) rotational torque can be detected. For this reason, the detection accuracy of the rotational torque of the motors 58 and 60 can be effectively increased, and the energy consumption for driving the motors 58 and 60 can be reduced more effectively. In addition, it is possible to suppress a decrease in the merchantability of the fuel cell vehicle 10 that uses the fuel cell system 20. The case where the fuel cell stack 12 generates power in an idle operation state in which the load of the fuel cell stack 12 is unlikely to fluctuate is, for example, the “minimum power generation amount” that cannot be used as power for unstable and traveling equipment. However, in the case of generating power with a power generation amount that can be used for the determination of power generation or non-power generation, or when power for traveling is not supplied by the fuel cell stack 12, for example, an accessory such as an in-vehicle TV when the vehicle is stopped This includes the case where only the power for the power source is generated.

  Further, a fuel gas system discharge flow path 40 for discharging hydrogen off gas from the fuel cell stack 12 and a fuel gas system circulation flow path 42 for returning the hydrogen off gas discharged from the fuel cell stack 12 to the fuel cell stack 12. And a purge valve 50 provided in the exhaust drainage flow path 48 connected to the fuel gas system discharge flow path 40, and a hydrogen pump 46 is provided in the fuel gas system circulation flow path 42 to add hydrogen off-gas. The rotation control rotational torque detecting means 54 is a circulating pump that pressurizes and discharges. The purge valve 50 is opened when the power generation operation of the fuel cell stack 12 is stopped, and the hydrogen pump 46 is continuously driven for a predetermined time during a scavenging process. One motor 58 (or 60) of the two motors 58, 60 is rotated or stopped at a constant speed, and at the same time, the other motor 60 (or 58) is added. Or, after decelerating, the rotational torque required to rotate at least one motor 58 (or 60) of the two motors 58, 60 when the two motors 58, 60 are rotated synchronously is detected. It can also be set as the structure to do. In this configuration, the rotation control rotational torque detecting means 54 rotates at least one motor 58 (or 60) in a situation where it is not required to change the pressure of the hydrogen pump 46 from the aspect of the scavenging process. Torque can be detected. For this reason, the detection accuracy of the rotational torque of the motors 58 and 60 can be effectively increased, and the energy consumption for driving the motors 58 and 60 can be reduced more effectively. Moreover, since the motors 58 and 60 are driven at a high rotation for a long time, the thermal expansion of the components of the hydrogen pump 46 causes the two saddle-shaped rotors 72 and 74 and between the saddle-shaped rotors 72 and 74 and the casing 66. The gap between the two motors 58 and 60 is likely to be reduced, and an appropriate phase difference between the two motors 58 and 60 can be obtained more accurately.

  In the present embodiment, a rotation angle sensor can be provided in each of the motors 58 and 60 for the purpose of detecting the rotational speed of the motors 58 and 60, for example. Further, for the purpose of reducing the cost compared to the case where a rotation angle sensor is provided, each motor 58 is detected from the detected current waveform, which has been conventionally considered to be used in a sensorless form such as a DC brassless motor. , 60, and the time corresponding to the plurality of positions, the rotational speed of the motors 58, 60, etc. can be obtained using a method of detecting the rotational speed of the motors 58, 60 differentiated over time.

  Further, in the present embodiment, the case where the hydrogen pump 46 that pressurizes and discharges the hydrogen off-gas is a pressure pump that is a Roots pump type, but the present invention is not limited to such a configuration. However, the present invention can also be applied to the case where the air compressor 32 that pressurizes and discharges air is a root pump pump.

  In the present embodiment, the case where the two motors 58 and 60 are provided on both sides of the casing 66 constituting the hydrogen pump 46 has been described, but the present invention is not limited to such a configuration. The two motors 58 and 60 are provided only on one side of the casing 66 constituting the hydrogen pump 46, and the two motors 58 are provided by a part of the rotor rotating shafts 68 and 70 to which the two saddle-shaped rotors 72 and 74 are fixed. , 60 motor drive shafts 86 and 88 can be configured. In this case, the effect that the heat generated by the rotation of the two motors 58 and 60 from both sides of the casing 66 is easily and efficiently transmitted to the components in the casing 66 efficiently is substantially the same as that of the present embodiment. Inferior to form. However, even in this configuration, the motor drive shafts of the two motors 58 and 60 are constituted by a part of the two rotor rotation shafts 68 and 70 provided with the two saddle-shaped rotors 72 and 74. The rotor rotating shafts 68 and 70 can be rotationally driven by the two motors 58 and 60 without using a gear mechanism, effectively preventing inconvenience caused by oil and improving the mountability. The effect is obtained in the same manner as in the present embodiment.

  In the above description, the hydrogen pump 46 or the air compressor 32 is a pressure pump that is a Roots pump type. However, the present invention is not limited to such a configuration. The present invention is implemented even in the case of a pressurizing pump that is a biaxial rotary pump in which a rotor other than a saddle-shaped rotor, for example, a screw-shaped rotor whose outer peripheral surface is a non-cylindrical surface is provided on the outer diameter side of the rotor rotation shaft it can.

1 is a basic configuration diagram of a fuel cell vehicle equipped with a fuel cell system according to an embodiment of the present invention. 1 is a basic configuration diagram of a fuel cell system according to an embodiment of the present invention. It is a schematic sectional drawing which shows the hydrogen pump shown in FIG. It is AA schematic sectional drawing of FIG. 5 is a flowchart showing an optimal condition motor drive control method for rotating two motors in synchronization with each other under the condition that the rotational torque of the motor is minimized in the embodiment according to the present invention. In embodiment which concerns on this invention, it is a figure which shows an example of the relationship between the virtual phase difference of the two motors which comprise a hydrogen pump, and the detected value of the rotational torque of one motor. 1 is a schematic diagram of an example of a conventional hydrogen pump for a fuel cell system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Fuel cell vehicle, 12 Fuel cell stack (FC), 14 Battery, 16 Driving motor, 18 Wheel, 20 Fuel cell system, 22 Control part, 24 Oxidation gas path, 26 Fuel gas path, 28 Oxidation gas supply flow path, 30 Oxidation gas system discharge flow path, 32 Air compressor, 34 Humidifier, 38 Fuel gas supply flow path, 40 Fuel gas system discharge flow path, 42 Fuel gas system circulation flow path, 44 Fuel gas supply flow path, 46, 46a Hydrogen Pump, 48 Exhaust drain passage, 50 Purge valve, 52 Motor drive control means, 54 Rotation control rotational torque detection means, 56 Optimal condition motor drive control means, 58, 60 Motor, 62 Suction port, 64 Discharge port, 66 Casing, 68, 70 Rotor rotation shaft, 72, 74 Spider rotor, 76, 78 Motor case, 80 Motor rotor, 82 Motor stator, 84 rotor space, 86, 88 motor drive shaft, 92 motor, 94 motor drive shaft, 96 bearing, 98 driven shaft, 100, 102 gear, 104 seal member.

Claims (11)

A fuel cell that generates electricity by an electrochemical reaction of the reaction gas; and
A pressurizing pump for pressurizing and discharging the supplied reaction gas;
A fuel cell system comprising a control unit,
The pressure pump is
Two rotor rotation shafts provided in the casing so as to be rotatable in parallel with each other;
Two rotors provided on the outer diameter side of each rotor rotation shaft and facing each other;
An inlet provided in the casing for receiving the reaction gas;
A discharge port provided in the casing for sending out the reaction gas;
A two-shaft rotary pump comprising two motors constituting each motor drive shaft by a part of each rotor rotary shaft,
The control unit controls the rotational drive of each motor so as to rotate the two motors in the reverse direction in synchronization with each other.   The pressurizing pump is a volume compression type roots type pump type provided with two saddle-shaped rotors which are provided on the outer diameter side of each rotor rotating shaft and are opposed to each other. Fuel cell system. The fuel cell system according to claim 1 or 2,
2. A fuel cell system characterized in that two gears meshing with each other for synchronizing the rotation of the two rotor rotating shafts are not coupled. In the fuel cell system according to any one of claims 1 to 3,
The two motors are provided on both sides of the casing. The fuel cell system according to any one of claims 1 to 4, wherein
The control unit
At least one of the two motors when rotating one motor of the two motors at a constant speed and simultaneously rotating the two motors after accelerating or decelerating the other motor A rotational control rotational torque detecting means for detecting rotational torque necessary to rotate the motor of the motor;
Optimal condition motor drive that controls the drive of the two motors so that the two motors rotate in synchronism with the optimum condition in which the detected rotational torque of at least one of the two motors is minimized. And a fuel cell system. The fuel cell system according to claim 5, wherein
The rotation control rotational torque detection means rotates or stops one of the two motors at a constant speed when the fuel cell power generation operation is stopped or when a torque command for a load connected to the fuel cell is constant. At the same time, after accelerating or decelerating the other motor, detecting the rotational torque required to rotate at least one of the two motors when rotating the two motors synchronously A fuel cell system. The fuel cell system according to claim 5, wherein
Used as a vehicle-mounted fuel cell system that is mounted on a vehicle and supplies power directly or via a power storage unit to a driving motor that is a driving source of the vehicle,
Further, the rotation control rotational torque detecting means rotates or stops one of the two motors at a constant speed and accelerates or accelerates the other motor when a fuel cell start command signal is input from the vehicle side. A fuel cell system for detecting a rotational torque required to rotate at least one of two motors when the two motors are rotated synchronously after being decelerated. The fuel cell system according to claim 5, wherein
Used as a vehicle-mounted fuel cell system that is mounted on a vehicle and supplies power directly or via a power storage unit to a driving motor that is a driving source of the vehicle,
Further, the rotation control rotational torque detecting means rotates one of the two motors at a constant speed or stops at the same time when the fuel cell start / stop command signal is input from the vehicle side. A fuel cell system for detecting a rotational torque required to rotate at least one of two motors when the two motors are rotated synchronously after being accelerated or decelerated. The fuel cell system according to claim 5, wherein
Used as a vehicle-mounted fuel cell system that is mounted on a vehicle and supplies power directly or via a power storage unit to a driving motor that is a driving source of the vehicle,
Further, the rotation control rotational torque detection means causes the vehicle motor to continuously idle at a constant speed when the vehicle stops running, or to cause the fuel cell to generate power in an idle operation state in which the load of the fuel cell is unlikely to fluctuate. Or, when an idle operation command signal that instructs not to extract regenerative power from the traveling motor even if the vehicle is decelerated during traveling of the vehicle is input, one of the two motors is rotated or stopped at a constant speed. At the same time, after accelerating or decelerating the other motor, detecting the rotational torque required to rotate at least one of the two motors when rotating the two motors synchronously A fuel cell system. The fuel cell system according to claim 5, wherein
Used as a vehicle-mounted fuel cell system that is mounted on a vehicle and supplies power directly or via a power storage unit to a driving motor that is a driving source of the vehicle,
Further, the rotation control rotational torque detection means stops the power generation operation of the fuel cell from the vehicle side when the required power generation amount required for the fuel cell is equal to or less than a predetermined value that is set in advance and exceeds the predetermined value again. When a power generation stop command signal instructed to stop the power generation operation of the fuel cell is input in the intermittent mode for restarting the power generation operation, one of the two motors is rotated or stopped at a constant speed. At the same time, after accelerating or decelerating the other motor, detecting the rotational torque required to rotate at least one of the two motors when rotating the two motors synchronously A fuel cell system. The fuel cell system according to claim 5, wherein
A discharge passage for discharging the fuel gas-based gas from the fuel cell;
A circulation channel for recirculating the fuel gas-based gas discharged from the fuel cell to the fuel cell;
A discharge valve provided in the exhaust drainage channel connected to the discharge channel,
The pressurizing pump is a circulating pump that is provided in the circulation channel and pressurizes and discharges the fuel gas system gas that is a reaction gas,
The rotational control rotational torque detecting means opens the discharge valve when the fuel cell power generation operation is stopped, and drives one of the two motors at a constant speed during a scavenging process in which the pressure pump is continuously driven for a predetermined time. Rotation torque required to rotate at least one of the two motors when rotating or stopping at the same time and simultaneously accelerating or decelerating the other motor and then rotating the two motors synchronously A fuel cell system characterized by

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