Air valve control device

Abstract

The present invention provides an air valve control device that enables the recovery of frozen air valves. [Solution] The device includes a control device 21 that determines whether or not freezing has occurred in the air valve 16, including that the difference between the indicated opening value of the air valve 16 and the detected opening value of the air valve 16 is greater than or equal to a predetermined value, and that the outside air temperature is below a predetermined temperature, and determines whether or not the conditions are met. If the conditions are met and a recovery operation is performed multiple times to cause the air valve 16 to open and close, the control device 21 makes the indicated opening value for the opening operation in the current recovery operation greater than the indicated opening value for the opening operation in the previous recovery operation.

Description

Technical Field

[0001] The present invention relates to a control device for an air valve that controls the opening degree of the air valve.

Background Art

[0002] The control device for an internal combustion engine described in Patent Document 1 controls the start and stop of supercharging of a supercharger that forcibly sends intake air to a throttle valve. When the temperature in the stopped state of the internal combustion engine is below a predetermined reference temperature, the control device for the internal combustion engine starts supercharging of the supercharger and forcibly sends intake air to the throttle valve. Then, the intake air sent to the throttle valve blows off moisture from the throttle valve to suppress freezing of the throttle valve.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the water generated when the fuel cell generates electricity passes through the exhaust flow path of the gas connected to the fuel cell. In a low-temperature environment, since the generated water freezes the air valve provided in the exhaust flow path, it is desirable to eliminate the freezing of the air valve and restore the valve opening function of the air valve. Such problems are common not only to the air valve provided in the drainage flow path but also to the air valve provided in the intake air flow path like the throttle valve described above.

Means for Solving the Problems

[0005] An air valve control device that solves the above problems is an air valve control device that controls the opening and closing operations of an air valve, and includes a determination unit that determines whether or not conditions are met, including that the difference between the indicated opening value of the air valve and the detected opening value of the air valve is greater than or equal to a predetermined value, and that the ambient temperature is less than or equal to a predetermined temperature, as conditions for determining whether or not freezing has occurred in the air valve; and an instruction unit that, when the determination unit determines that the conditions are met and causes the air valve to perform a recovery operation to perform the opening and closing operations multiple times, sets the indicated opening value of the opening operation in the current recovery operation to be greater than the indicated opening value of the opening operation in the previous recovery operation. [Effects of the Invention]

[0006] This air valve control device can accelerate the recovery of an air valve that has become stuck due to freezing by gradually increasing the opening degree instruction value for the recovery operation performed multiple times. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a diagram showing the configuration of the air valve control device. [Figure 2] Figure 2 is a flowchart showing the recovery process. [Modes for carrying out the invention]

[0008] Hereinafter, an embodiment in which the air valve control device 21 is applied to the fuel cell system 10 will be described with reference to Figures 1 and 2. As shown in Figure 1, the fuel cell system 10 is mounted on a vehicle and outputs electricity to power the vehicle in response to requests from the driver. The fuel cell system 10 comprises a fuel cell 11, an anode gas path 12, a cathode gas path 13A, and a control device 21.

[0009] The fuel cell 11 has a stack structure in which multiple single power generation cells are stacked. Each single cell has an electrolyte membrane sandwiched between separators on both sides. The fuel cell 11 generates electricity through an electrochemical reaction between fuel gas supplied from the anode gas path 12 and oxygen contained in the air supplied from the cathode gas path 13A.

[0010] The cathode gas path 13A includes an air compressor 14 for taking in air and an air shut-off valve 15 that adjusts the passage and shut-off of air in the supply path from which air is supplied by the air compressor 14. The cathode gas path 13A also includes an outlet path 13B for discharging air from the fuel cell 11 and an air valve 16 that adjusts the flow rate of air discharged from the outlet path 13B. The air compressor 14 compresses the air so that the air passing through the cathode gas path 13A reaches the fuel cell 11 at a predetermined pressure. The air valve 16 is located in the middle of the cathode gas path 13A and discharges the air and generated water released from the fuel cell 11 into the discharge path 13C at a predetermined timing. The cathode gas path 13A performs air supply by controlling the air compressor 14, the air shut-off valve 15, and the air valve 16 with the control device 21.

[0011] The air valve 16 is a normally closed valve, and the valve body may be continuously biased to the fully closed position by the biasing force of a spring. The air valve 16 may also have its valve body moved toward the open position by the output of a DC motor.

[0012] The opening degree sensor 31 detects the opening degree of the air valve 16. The opening degree sensor 31 inputs the detection result to the control device 21. The temperature sensor 32 detects the external temperature of the air valve 16. The temperature sensor 32 inputs the detection result to the control device 21.

[0013] The control device 21 consists of a microcomputer equipped with a CPU, ROM, and RAM for performing logical operations. The control device 21 includes a control unit 22, a storage unit 23, and a drive unit 24. The control unit 22 drives the fuel cell 11 by executing a program stored in the storage unit 23. The control unit 22 controls the operation of the fuel cell 11 by causing the drive unit 24 to supply gas in the anode gas path 12 and the cathode gas path 13A. The control unit 22 controls the position of the air valve 16. For example, the control unit 22 sets an opening value for the air valve 16 based on inputs from the opening sensor 31 and the temperature sensor 32, and causes the drive unit 24 to perform a recovery operation of the air valve 16 based on the opening value. The control unit 22 is an example of a judgment unit and an instruction unit.

[0014] The memory unit 23 stores a program for driving the fuel cell 11. The memory unit 23 stores various data for driving the air valve 16 in the drive unit 24. The various data include a verification instruction value, an estimated freezing opening, and an estimated freezing temperature. The various data also include a recovery instruction value, a closing instruction value, the number of opening and closing cycles, an expansion threshold, and a step drive amount. The verification instruction value, the estimated freezing opening, and the estimated freezing temperature are used to determine if freezing has occurred. The recovery instruction value, the closing instruction value, the number of opening and closing cycles, the expansion threshold, and the step drive amount are used for the recovery operation.

[0015] The verification instruction value is the opening degree instruction value used to determine freezing. From the viewpoint of suppressing overload of the air valve 16, the verification instruction value may be an opening degree smaller than the fully open position of the valve body in the air valve 16. The verification instruction value may also be calculated by the control unit 22. For example, the control unit 22 may calculate the flow rate of the reaction gas from the target power generation amount and calculate the verification instruction value based on the calculated flow rate of the reaction gas.

[0016] The estimated freezing opening is a threshold value for initiating recovery operations and is an example of a predetermined value. The control unit 22 includes the condition that the difference between the verification instruction value and the value detected by the opening sensor 31 is greater than or equal to the estimated freezing opening when determining that freezing has occurred in the air valve 16. The estimated freezing opening may be 5% of the verification instruction value.

[0017] The freezing estimated temperature is a threshold value of the outside air temperature for starting the recovery operation, and is an example of a predetermined temperature. The control unit 22 includes that the detected value of the temperature sensor 32 is less than or equal to the freezing estimated temperature in the condition for determining that freezing has occurred in the air valve 16.

[0018] The recovery instruction value is an opening degree instruction value used for the opening operation of the recovery operation. The recovery instruction value in the first recovery operation is an opening degree smaller than the opening degree corresponding to the fully open position of the valve element, and may be 1 / 2 or more of the verification instruction value.

[0019] The closing operation instruction value is an opening degree instruction value smaller than the recovery instruction value used for the closing operation of the recovery operation. The closing operation instruction value in the first recovery operation may be the opening degree corresponding to the fully closed position of the valve element. The closing operation instruction value in the recovery operation after the second time may be the detected value of the opening degree sensor 31 detected in the opening operation in the previous recovery operation.

[0020] The number of opening and closing operations is the number of times of executing the unit operation in one recovery operation. One recovery operation is composed of one or more unit operations. The unit operation is composed of one opening operation and one closing operation in the air valve 16. The number of opening and closing operations is one or more.

[0021] The expansion threshold value is used for determining whether to update the recovery instruction value. The control unit 22 includes that the deviation between the recovery instruction value and the recovery opening degree in the current recovery operation is greater than or equal to the lower limit value of the expansion threshold value and less than or equal to the upper limit value of the expansion threshold value in the condition for making the recovery instruction value in the next recovery operation larger than that in the current recovery operation. The recovery opening degree is the detected value of the opening degree sensor 31 in the opening operation in the current recovery operation. The lower limit value of the expansion threshold value is a value estimated to have the freezing eliminated based on the small deviation between the recovery instruction value and the recovery opening degree. The upper limit value of the expansion threshold value is a value estimated that the elimination of freezing is not expected based on the large deviation between the recovery instruction value and the recovery opening degree. The expansion threshold value may be 5% or more and 95% or less of the recovery instruction value in the opening operation of the current recovery operation.

[0022] The step drive amount is used for updating the recovery instruction value. The control unit 22 adds the step drive amount to the recovery instruction value in the current recovery operation to update the recovery instruction value in the next recovery operation. The step drive amount may be a difference value between the opening degree corresponding to the fully open position of the valve body and the recovery instruction value before update, or a difference value between the verification instruction value and the recovery instruction value before update, or a value obtained by dividing these difference values by a predetermined number of times. The predetermined number of times may be the maximum number of times the recovery operation is executed.

[0023] As shown in FIG. 2, before starting the fuel cell 11, the control device 21 sets the verification instruction value as the opening degree instruction value of the air valve 16 (step S11). Next, the control device 21 determines whether the air valve 16 is frozen (step S12). When the deviation between the verification target value, which is the detected value of the opening degree sensor 31, and the verification instruction value is less than the estimated freezing opening degree (NO in step S12), the control device 21 determines that the recovery operation is unnecessary and executes the valve opening process for starting the fuel cell 11 (step S15). On the other hand, when the deviation between the verification target value and the verification instruction value is greater than or equal to the estimated freezing opening degree and the detected value of the temperature sensor 32 is less than or equal to the estimated freezing temperature (YES in step S12), the control device 21 executes the recovery operation (step S13).

[0024] Here, the control device 21 sets the recovery instruction value as the opening degree instruction value in the opening operation of the unit operation, and sets the closing instruction value as the opening degree instruction value in the closing operation, and executes the closing operation and the opening operation of the air valve 16 for the number of opening and closing times.

[0025] Next, the control device 21 determines the degree of recovery of the air valve 16 (step S14). As part of determining the degree of recovery, the control device 21 determines whether the difference between the recovery opening and the recovery instruction value in the current recovery operation is greater than or equal to the lower limit of the expansion threshold. If the difference between the recovery opening and the recovery instruction value is less than the lower limit of the expansion threshold (YES in step S14), the control device 21 performs the valve opening process to start the fuel cell 11 (step S15). On the other hand, if the difference between the recovery opening and the recovery instruction value is greater than or equal to the lower limit of the expansion threshold (NO in step S14), the control device 21 determines whether or not to update the recovery instruction value in the recovery operation (step S21).

[0026] Next, if the difference between the recovery opening and the recovery instruction value exceeds the upper limit of the expansion threshold, the control device 21 determines that recovery is not expected (NO in step S21) and notifies the outside that freezing has occurred in the air valve 16 (step S23). On the other hand, if the difference between the recovery opening and the recovery instruction value is less than or equal to the upper limit of the expansion threshold (YES in step S21), the control device 21 sets the next recovery instruction value to be increased by the amount of the step drive from the current recovery instruction value (step S22). Then, the control device 21 performs a recovery operation using the next recovery instruction value and determines the degree of recovery by said recovery operation (steps S13, step S14).

[0027] Thus, if the control device 21 determines that freezing has occurred in the air valve 16 and that recovery can be expected through the current recovery operation, it increases the recovery instruction value in the next recovery operation among the multiple recovery operations that will be performed, including the current one.

[0028] For example, the control device 21 stores a verification instruction value of 20°, an estimated freezing opening degree of 5% of the verification instruction value, an estimated freezing temperature of -10°, and an expansion threshold of 5% to 95% of the recovery instruction value. The control device 21 also stores a recovery instruction value of 10°, a closing instruction value of 0.5°, a step drive amount of 10°, and 3 opening / closing cycles.

[0029] Then, before starting the fuel cell 11, the control device 21 outputs a drive signal to the drive unit 24 to achieve the verification instruction value (20°). If the value to be verified is 0.5°, the control device 21 determines that the discrepancy between the value to be verified and the verification instruction value is greater than or equal to the estimated freezing opening. Also, if the value detected by the temperature sensor 32 is -30°C, the control device 21 determines that the value detected by the temperature sensor 32 is below the estimated freezing temperature. As a result, the control device 21 determines that freezing has occurred in the air valve 16 and causes the drive unit 24 to perform a recovery operation on the air valve 16.

[0030] Here, the control device 21 outputs a drive signal to the drive unit 24 alternately three times to achieve the recovery instruction value (10°) and a drive signal to achieve the closing instruction value (0.5°), thereby executing the current recovery operation. At this time, if the recovery opening in the current recovery operation is 3°, the control device 21 determines that the difference between the recovery opening and the recovery instruction value is included in the widening threshold. Next, the control device 21 sets the recovery instruction value for the next recovery operation to a value (20°) which is the recovery instruction value (10°) from the current recovery operation plus a step drive amount (10°). Then, the control device 21 executes the second recovery operation using the recovery instruction value which has been increased step by step.

[0031] According to the above embodiment, the following effects can be obtained. (1) The gradual increase in the recovery instruction value during the opening operation of the recovery operation changes the vibration and frictional force acting on the valve body toward resolving the sticking. As a result, the control device 21 can accelerate the recovery of the air valve 16 that has become stuck due to freezing.

[0032] (2) The function of the air valve 16, which is to allow air to flow at a predetermined flow rate, is in accordance with the opening degree of the air valve 16. The control device 21, which uses the opening degree as the recovery instruction value and the expansion threshold to determine the degree of recovery, increases the certainty that the function of the air valve 16 has been restored.

[0033] The above embodiment can be implemented with the following modifications. The following modifications can be combined with the above embodiment or other modifications to the extent that they do not contradict the technical standards. The control device 21 may omit the process of determining the degree of recovery of the air valve 16 (step S14) and the process of determining whether or not to update the recovery instruction value (step S21). In other words, after the initial recovery operation using the recovery instruction value (step S13), the control device 21 may repeat, alternately, the updating of the recovery instruction value (step S22) and the recovery operation using the updated recovery instruction value (step S13) a predetermined number of times.

[0034] Furthermore, the control device 21 may perform torque control of the air valve 16 during the recovery operation. In this case, the control device 21 stores the voltage value or current value that determines the output torque of the DC motor as the recovery instruction value, the closing instruction value, and the step drive amount. The recovery instruction value in the initial recovery operation and the recovery instruction value updated by the step drive amount are less than or equal to the allowable voltage or allowable current of the DC motor. After the initial recovery operation (step S13), the control device 21 may then alternately repeat the process of updating the recovery instruction value (step S22) and performing a recovery operation using the updated recovery instruction value (step S13) for a predetermined number of times.

[0035] The air valve 16 can be any valve whose opening degree is changed by the drive of the valve body, and may be a butterfly valve, a rotary valve which adjusts the flow rate with a rotating cylindrical valve, or a cone valve which adjusts the passage cross-sectional area with a cone-shaped valve.

[0036] The control device 21 may be applied to the throttle valve in the intake passage of an internal combustion engine. An internal combustion engine comprises a cylinder in which a piston is arranged to reciprocate, and an injector that injects fuel into the cylinder. The cylinder is connected to the intake passage via an intake valve. The cylinder produces a mixture of intake air introduced through the intake passage and fuel injected from the injector. An ignition device ignites the mixture in the combustion chamber by spark discharge. A throttle valve, which is an example of an air valve, adjusts the intake airflow rate in the intake passage. [Explanation of Symbols]

[0037] 10...Fuel cell system, 16...Air valve, 21...Control device, 22...Control unit, 23...Storage unit, 24...Drive unit, 31...Opening degree sensor, 32...Temperature sensor.

Claims

[Claim 1] An air valve control device that controls the opening and closing operations of an air valve, A determination unit that determines whether or not the conditions for determining whether or not freezing has occurred in the air valve include the condition that the difference between the indicated opening value of the air valve and the detected opening value of the air valve is greater than or equal to a predetermined value, and that the outside air temperature is below a predetermined temperature, and determines whether or not the above conditions are met. The determination unit determines that the above conditions are met and causes the air valve to perform a recovery operation that involves opening and closing the air valve multiple times, and includes an indicator unit that sets the opening degree indicator value for the opening operation in the current recovery operation to be greater than the opening degree indicator value for the opening operation in the previous recovery operation. An air valve control device characterized by the following features.

Images