JP2008215175A - Compressor and fuel cell system provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air compressor having a compact compressed gas cooling system, and a fuel cell system provided with the air compressor. <P>SOLUTION: In this compressor 14 provided with a driving motor 52 and an air compression section (compression section) 51 for compressing gas by the driving motor 52, a cooling fan 55 driven by the driving motor 52 is further provided for taking in outside air, and an air-cooled intercooler (heat exchanger) 59 is furthermore provided for cooling compressed gas which is compressed in the air compressor section 51 by the outside air. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a compressor and a fuel cell system including the compressor, and more particularly to a compressor used to compress oxidizing gas in the fuel cell system.

In a fuel cell system, air compressed by a compressor is used as an oxidizing gas for a power generation reaction of the fuel cell. Since the compressed air has a high temperature, conventionally, a technique for cooling the compressed air using cooling water for cooling the fuel cell is known (see, for example, Patent Documents 1 to 3).
JP 2002-305857 A JP 2000-249066 A JP 2003-118396 A

  However, since the cooling water is for cooling the fuel cell, the water temperature is as high as 70 to 80 ° C., and the temperature difference from the compressed air temperature is small. Since the heat exchange efficiency η can be expressed by the following equation, for heat exchangers with the same efficiency, T1 (out) [compressed gas outlet temperature] increases as T2 (in) [cooling water inlet temperature] increases. End up.

However, T1 (in): compressed gas inlet temperature, T1 (out): compressed gas outlet temperature, T2 (in): cooling water inlet temperature

  For this reason, it is necessary to increase the size of the heat exchanger in order to cool it to a desired gas temperature. However, in that case, for example, the size of the space when incorporated in a vehicle fuel cell system becomes a problem.

  The present invention has been made in view of the above circumstances, and provides an air compressor capable of sufficiently cooling compressed gas while avoiding an increase in the size of a heat exchanger, and a fuel cell system including the air compressor. With the goal.

  In order to achieve the above object, the present invention provides a cooling fan driven by the driving motor in a compressor including a driving motor and a compression unit that compresses gas using the driving motor as a driving source; And a heat exchanger that cools the compressed gas compressed by the compression unit by outside air taken in by the cooling fan.

  According to the compressor of this configuration, compressed gas is generated using the drive motor as a drive source, and the generated compressed gas is cooled by the outside air introduced by the cooling fan that is also driven by the drive motor. In this case, since the outside air is used as the cooling air, for example, the temperature difference with the compressed gas can be made larger than when the cooling water for cooling the fuel cell is used. According to this, since the cooling efficiency in the heat exchanger can be improved, the compressed gas can be sufficiently cooled while avoiding an increase in the size of the heat exchanger.

  The cooling fan may be provided coaxially with the driving motor. In this configuration, the rotation of the driving motor can be directly transmitted to the cooling fan, and the structure is simple. In the present invention, the cooling fan and the heat exchanger are connected by a duct.

  The cooling fan is, for example, a sirocco fan or an axial fan.

  Furthermore, the fuel cell system of the present invention includes the above-described compressor in an oxidizing gas flow path, and the oxidizing gas is compressed and cooled by the compressor and supplied to the fuel cell. In this configuration, the cooling efficiency is high because the compressed air is not cooled using the cooling water of the fuel cell, but is cooled using the outside air. For this reason, it is possible to sufficiently cool the compressed gas while avoiding an increase in the size of the heat exchanger.

  According to the present invention, the compressed gas is cooled by using the outside air having a high temperature difference from the conventionally used compressed gas as cooling air, so that the compressed gas is sufficiently cooled while avoiding an increase in the size of the heat exchanger. Can do.

  Next, an embodiment of the present invention will be described with reference to the drawings. First, a fuel cell system 1 to which a compressor according to this embodiment is applied will be described with reference to FIG.

  FIG. 1 shows a schematic configuration of a fuel cell system 1 in the present embodiment. As shown in the figure, a fuel cell system 1 includes a fuel cell 2, an oxidizing gas supply / discharge system (hereinafter also referred to as an oxidizing gas piping system) 3 for supplying air (oxygen) as an oxidizing gas to the fuel cell 2, a fuel A fuel gas supply / discharge system (hereinafter also referred to as a fuel gas piping system) 4 for supplying hydrogen as a gas to the fuel cell 2, a refrigerant piping system 5 for supplying a refrigerant to the fuel cell 2 and cooling the fuel cell 2, A power system 6 that charges and discharges system power and a control unit 7 that performs overall control of the entire system are provided.

  The fuel cell 2 is, for example, a polymer electrolyte fuel cell, and has a stack structure in which a large number of single cells are stacked. A single cell of the fuel cell 2 has an air electrode on one surface of an electrolyte made of an ion exchange membrane, a fuel electrode on the other surface, and a pair of separators so as to sandwich the air electrode and the fuel electrode from both sides. have. The fuel gas is supplied to the fuel gas flow path of one separator and the oxidizing gas is supplied to the oxidizing gas flow path of the other separator, and the fuel cell 2 generates electric power by this gas supply.

  The oxidizing gas piping system 3 has a supply path 11 through which the oxidizing gas supplied to the fuel cell 2 flows, and a discharge path 12 through which the oxidizing off gas discharged from the fuel cell 2 flows. The supply path 11 is provided with a compressor 14 that takes in the oxidizing gas via the filter 13, and a humidifier 15 that humidifies the oxidizing gas fed by the compressor 14. The oxidizing off-gas flowing through the discharge path 12 is subjected to moisture exchange by the humidifier 15 through the back pressure regulating valve 16, and is finally exhausted into the atmosphere outside the system as exhaust gas. The compressor 14 takes in the oxidizing gas in the atmosphere by driving the motor 14a.

  The fuel gas piping system 4 includes a hydrogen supply source 21, a supply path 22 through which hydrogen gas supplied from the hydrogen supply source 21 to the fuel cell 2 flows, and a supply path for supplying hydrogen offgas (fuel offgas) discharged from the fuel cell 2. 22, a circulation path 23 for returning to the junction point A of 22, a pump 24 that pumps the hydrogen off-gas in the circulation path 23 to the supply path 22, and a discharge path 25 that is branched and connected to the circulation path 23. .

  The hydrogen supply source 21 is composed of, for example, a high-pressure tank or a hydrogen storage alloy, and is configured to be able to store, for example, 35 MPa or 70 MPa of hydrogen gas. When the main valve 26 of the hydrogen supply source 21 is opened, hydrogen gas flows out into the supply path 22. The hydrogen gas is finally depressurized to about 200 kPa, for example, by the pressure regulating valve 27 and other pressure reducing valves, and supplied to the fuel cell 2.

  A shutoff valve 28 is provided on the upstream side of the junction point A of the supply path 22. The hydrogen gas circulation system is configured by sequentially communicating a flow path downstream from the confluence point A of the supply path 22, a fuel gas flow path formed in the separator of the fuel cell 2, and the circulation path 23. Yes. The hydrogen pump 24 circulates and supplies hydrogen gas in the circulation system to the fuel cell 2 by driving the motor 24a.

  The discharge path 25 is provided with a purge valve 33 that is a shut-off valve. By appropriately opening the purge valve 33 when the fuel cell system 1 is operating, impurities in the hydrogen off gas are discharged together with the hydrogen off gas to a hydrogen diluter (not shown). By opening the purge valve 33, the concentration of impurities in the hydrogen off-gas in the circulation path 23 decreases, and the concentration of hydrogen in the hydrogen off-gas supplied in circulation increases.

  The refrigerant piping system 5 includes a refrigerant circulation channel 41 communicating with the cooling channel in the fuel cell 2, a cooling pump 42 provided in the refrigerant circulation channel 41, and a radiator that cools the refrigerant discharged from the fuel cell 2. 43, a bypass passage 44 that bypasses the radiator 43, and a three-way valve (switching valve) 45 that sets the flow of cooling water to the radiator 43 and the bypass passage 44. The cooling pump 42 circulates and supplies the refrigerant in the refrigerant circulation passage 41 to the fuel cell 2 by driving the motor 42a.

  The power system 6 includes a high-voltage DC / DC converter 61, a battery 62, a traction inverter 63, a traction motor 64, and various auxiliary inverters 65, 66, and 67. The high-voltage DC / DC converter 61 is a direct-current voltage converter that adjusts the direct-current voltage input from the battery 62 and outputs it to the traction inverter 63 side, and the direct-current input from the fuel cell 2 or the traction motor 64. And a function of adjusting the voltage and outputting it to the battery 62. The charge / discharge of the battery 62 is realized by these functions of the high-voltage DC / DC converter 61. Further, the output voltage of the fuel cell 2 is controlled by the high voltage DC / DC converter 61.

  The battery 62 is configured such that battery cells are stacked and a constant high voltage is used as a terminal voltage, and surplus power can be charged or power can be supplementarily supplied under the control of a battery computer (not shown). The traction inverter 63 converts a direct current into a three-phase alternating current and supplies it to the traction motor 64. The traction motor 64 is, for example, a three-phase AC motor, and constitutes, for example, a main power source of a vehicle on which the fuel cell system 1 is mounted.

  The auxiliary machine inverters 65, 66, and 67 are electric motor control devices that control driving of the corresponding motors 14a, 24a, and 42a, respectively. Auxiliary machine inverters 65, 66, and 67 convert a direct current into a three-phase alternating current and supply it to motors 14a, 24a, and 42a, respectively. Auxiliary machine inverters 65, 66, and 67 are, for example, pulse width modulation type PWM inverters, which convert a DC voltage output from fuel cell 2 or battery 62 into a three-phase AC voltage in accordance with a control command from control unit 7. The rotational torque generated by each motor 14a, 24a, 42a is controlled.

  The control unit 7 is configured as a microcomputer including a CPU, a ROM, and a RAM inside. The CPU executes a desired calculation according to the control program, and performs various processes and controls such as a thawing control of the pump 24 described later. The ROM stores control programs and control data processed by the CPU. The RAM is mainly used as various work areas for control processing. The control unit 7 inputs detection signals such as various pressure sensors, temperature sensors, and outside air temperature sensors used in the gas system (3, 4) and the refrigerant piping system 5, and outputs control signals to each component.

  Next, the configuration of the compressor 14 according to the present invention will be described in detail.

  As shown in FIG. 2, the compressor 14 according to the present embodiment includes an air compression unit (compression unit) 51 that has a compression space whose volume is changed by the rotation of the shaft 50 and compresses and sucks sucked air. And a driving motor 52 that rotationally drives the shaft 50 of the compression unit 51. Further, a cooling fan unit 53 is provided on the opposite side of the air compression unit 51 on the shaft extension of the drive motor 52.

  The cooling fan unit 53 includes a cooling fan 55 that is a sirocco fan fixed to the shaft 50, and a housing 56 that sucks and guides cooling air for cooling high-temperature compressed air to be described later. The air sucked into the housing 56 by the cooling fan 55 is guided to an air-cooled intercooler (heat exchanger) 59 via a duct 58 extending radially outward. The air-cooled intercooler 59 is supplied with high-temperature compressed air compressed by the air compression unit 51 through the supply path 11 and is cooled by cooling air (outside air) sucked by the cooling fan unit 53. The cooled compressed air is sent to the downstream fuel cell 2 through the supply path 11, and the cooling air used for cooling is discharged from the air-cooled intercooler 59 to the outside.

The operation of the compressor 14 configured in this way will be described.
When the drive motor 52 is driven, the compression space is compressed by the shaft 50 of the air compressor 51, and high-temperature compressed air is generated and discharged to the supply path 11. The compressed air is introduced into the air-cooled intercooler 59. Further, the cooling fan 55 of the cooling fan unit 53 fixed to the shaft 50 of the drive motor 52 rotates, and cooling air (outside air) is introduced into the housing 56 and flows into the air-cooled intercooler 59 through the duct 58. . In the air-cooled intercooler 59, the high-temperature compressed air is cooled by the cooling air, and the compressed air is used for the power generation reaction of the fuel cell 2 on the downstream side. The cooling air used for cooling is discharged to the outside.

  Thus, in the present embodiment, the outlet temperature of the compressed air is set to cool the compressed air by using the outside air having a temperature lower than the refrigerant temperature (70 to 80 ° C.) of the refrigerant piping system 5 conventionally used as the cooling air. Can be reduced. That is, since the cooling efficiency can be improved, a device necessary for cooling the compressed air (in this embodiment, the air-cooled intercooler 59 provided in the compressor 14) can be reduced in size. Therefore, it is particularly useful in a fuel cell system for vehicles with a small mounting space. In the present embodiment, since the compressor 14 includes the air-cooled intercooler 59, a separate cooling device (heat exchanger) is unnecessary.

As a modification, a configuration as shown in FIG. 3 may be used.
In the compressor 60 shown in FIG. 3, the cooling fan unit 63 includes a cooling fan 65 that is an axial fan. The cooling fan 65 is an axial fan that sucks air from the outside in the axial direction and discharges the air toward the outside in the radial direction. An air-cooled intercooler (heat exchanger) 69 is provided upstream of the suction side on the axial extension of the cooling fan 65. Since other configurations are the same as those in the above embodiment, description thereof is omitted.

  In this example configured as described above, when the driving motor 52 is driven during the operation of the compressor 14, the compression space is compressed by the shaft 50 of the air compressing unit 51, and high-temperature compressed air is generated to the supply path 11. Discharged. The compressed air is introduced into the air-cooled intercooler 69. In addition, the cooling fan 65 of the cooling fan unit 63 fixed to the shaft 50 of the drive motor 52 rotates, and cooling air (outside air) is taken into the cooling fan 65 side from the outside along the axial direction. In this process, the high-temperature compressed air that has passed through the air-cooled intercooler 69 and is supplied by the supply passage 11 is cooled. The compressed air is used for the power generation reaction of the fuel cell 2 on the downstream side. The cooling air used for cooling is exhausted radially outward by the cooling fan unit 63.

  Thus, also in the present embodiment, the cooling efficiency can be improved and the apparatus can be miniaturized as in the above-described embodiment.

  Needless to say, the direction of suction and exhaust of the cooling air may be opposite to the above. Moreover, although the compressor of this embodiment is applied to the fuel cell system, you may use it for another use.

1 is a system configuration diagram schematically illustrating an embodiment of a fuel cell system according to the present invention. It is sectional drawing which showed schematic structure of the compressor which concerns on this invention. It is sectional drawing which showed the modification of the compressor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 14 ... Compressor, 50 ... Shaft, 51 ... Air compression part (compression part), 52 ... Drive motor, 55 ... Cooling fan, 58 ... Duct, 59 ... Air-cooled intercooler (heat exchanger) , 60 ... Compressor, 69 ... Air-cooled intercooler (heat exchanger)

Claims (6)

In a compressor comprising a drive motor and a compression unit that compresses gas using the drive motor as a drive source,
A compressor comprising: a cooling fan driven by the driving motor; and a heat exchanger that cools compressed gas compressed by the compression unit by outside air taken in by the cooling fan.   The compressor according to claim 1, wherein the cooling fan is provided coaxially with the driving motor.   The compressor according to claim 1 or 2, wherein the cooling fan and the heat exchanger are connected by a duct.   The compressor according to any one of claims 1 to 3, wherein the cooling fan is a sirocco fan.   The compressor according to any one of claims 1 to 3, wherein the cooling fan is an axial fan.   A fuel cell system comprising the compressor according to any one of claims 1 to 5 in an oxidizing gas flow path, wherein the oxidizing gas is compressed and cooled by the compressor and supplied to the fuel cell.