JP2004133681A - Digital filter for actuators operation controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital filter capable of reducing a noise component of digital data showing a value regularly gradually decreasing or increasing in a state containing no noise component. <P>SOLUTION: This filter 42 is applied to a control circuit 10 for digital-controlling operation of a drive source 18 of an actuator on the basis of comparison of a target value of the actuator with a feedback signal value from a potentiometer 40 detecting an operation position of the actuator. The filter 42 is composed of a comparison calculation means. The comparison calculation means compares the output with the digital data outputted from an A/D converting circuit 41, and selectively outputs digital data equal to a comparison target with the digital data outputted from the A/D converting circuit 41, digital data larger than the digital data by one level, or digital data smaller by one level according to the comparison result. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a digital filter, and more particularly, to a digital filter used in a digital control circuit for feedback-controlling the operation of an electric door opening / closing control motor incorporated in an actuator of a vehicle air conditioner as a driving source of the actuator.
[0002]
[Prior art]
In an air conditioner for an automobile, an electric door is opened and closed as an actuator of a control valve body called an intake door for adjusting an intake ratio of outside air and inside air or an air mix door for adjusting a mixture ratio of cold air and hot air. An actuator using a control motor as a drive source is employed. A feedback control method is used for controlling the electric door opening / closing control motor (for example, see Patent Document 1).
[0003]
In the feedback control circuit described in Patent Document 1, the operating position of the electric door opening / closing control motor corresponding to the degree of opening of each door is detected by a potentiometer, and a feedback signal from the potentiometer is converted into a digital signal. The operation of the electric door opening / closing control motor is controlled to move the door to the desired opening based on the deviation between the signal and the target value corresponding to the desired door opening.
[0004]
By the way, if noise is superimposed on the feedback signal, it becomes difficult to perform appropriate feedback control. Therefore, it is conceivable to apply a digital filter to remove noise components.
[0005]
Some conventional digital filters use a smoothing method or an integration averaging method, or determine whether or not the data value at the center point is noise from five data values in order to remove spike noise. In some cases, spike-like noise is removed by making a determination and correcting the value of the data value determined to be the noise (for example, see Patent Document 2).
[0006]
[Patent Document 1]
JP-A-7-309120 (page 3-5, FIG. 1)
[Patent Document 2]
JP-A-8-330905 (page 2-3, FIG. 1)
[0007]
[Problems to be solved by the invention]
However, each of the conventional digital filters has a complicated configuration, and a digital filter which is output from a potentiometer with a simpler configuration and which can effectively remove noise components of a digital signal subjected to A / D conversion is desired. Had been rare.
[0008]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a digital filter having a relatively simple configuration that can reduce a noise component of digital data that exhibits a gradually decreasing or increasing value when no noise component is included.
[0009]
[Means for Solving the Problems]
The invention according to claim 1 is output from the potentiometer to digitally control the operation of the drive source of the actuator based on a comparison between a target value of the actuator and a feedback signal value from a potentiometer for detecting the operation position of the actuator. A digital filter connected to an A / D conversion circuit for sequentially digitizing an analog feedback signal to reduce noise of digital data output from the A / D conversion circuit, comprising a comparison operation means; The means compares the output with the digital data output from the A / D conversion circuit, and, in accordance with the comparison result, the output to be compared with the digital data output from the A / D conversion circuit. Output digital data equal to the data, digital data one step larger than the output digital data. Or and outputs one step of either small digital data selectively.
[0010]
According to the first aspect of the present invention, the comparison operation means outputs a digital signal equal to the output data to be compared with the digital data output from the A / D conversion circuit in accordance with a comparison result between the two inputs. Data, that is, digital data that does not change the data value, digital data one stage larger than the digital data, or digital data smaller by one stage, outputs one digital data. Since the digital value sequentially input from the A / D conversion circuit to the comparison operation means is a digital value corresponding to an analog value that gradually increases or decreases gradually from the potentiometer, the change in the digital value does not include a noise component under the situation where the noise component is not included. , At most one step at a time. The comparison operation means compares the output digital data with the digital data from the A / D conversion circuit. Even if the digital data has increased or decreased by more than two steps due to a noise component, the comparison operation means determines the difference in accordance with the comparison result. In this case, digital data indicating one step increase / decrease is output, and a digital signal in which the influence of noise is suppressed can be obtained.
[0011]
According to a second aspect of the present invention, in the first aspect of the present invention, the comparison operation means includes: an operation processing circuit; a first storage unit for storing digital data output from the operation processing circuit; A second storage unit for storing digital data output from the / D conversion circuit, and a comparator for comparing the two digital data stored in the first and second storage units, wherein the arithmetic processing circuit Outputting the digital data stored in the first storage unit when the same result is obtained as a result of comparison by the comparator, and storing the digital data stored in the first storage unit in the second storage unit. When the digital data is larger than the stored digital data, the digital data that is smaller by one step than the digital data stored in the first storage unit is output, and the digital data stored in the first storage unit is stored in the second storage unit. Storage And outputting a one step larger digital data than the digital data stored in said first storage unit is smaller than the digital data.
[0012]
According to the second aspect of the present invention, the comparison operation means can be composed of two storage units, a comparator and an operation processing circuit, whereby the present invention can be implemented relatively inexpensively and easily.
[0013]
According to a third aspect of the present invention, in the second aspect of the present invention, the arithmetic processing circuit can be configured by an up-down counter, thereby realizing the digital filter of the present invention by a combination of commercially available off-the-shelf products. can do.
[0014]
According to a fourth aspect of the present invention, in the first aspect of the invention, the driving source is an electric door opening / closing control motor of an air conditioner for a vehicle.
[0015]
The invention according to claim 5 is the invention according to claim 4, wherein the electric door opening / closing control motor operates each door of the air conditioner. As an air conditioner door whose operation is controlled by an actuator that uses the electric door opening / closing control motor as a drive source, an intake door for adjusting the intake ratio of outside air and inside air, and for adjusting the mixing ratio of cold air and hot air. In addition to the air mix door, there are a well-known separate door, mode door, fresh vent door, bi-level door, and the like.
[0016]
According to the fourth and fifth aspects of the present invention, the influence of noise can be substantially eliminated from the operation control of the electric motor of the air conditioner, that is, the electric door opening / closing control motor. It is possible to realize a comfortable interior environment.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, features of the present invention will be described in detail with reference to the illustrated embodiments.
[0018]
FIG. 1 schematically shows an electric circuit diagram of an actuator operation control device incorporating a digital filter according to the present invention. Prior to the description along FIG. 1, an example of an air conditioner for a vehicle to which the actuator operation control device according to the present invention is applied will be described with reference to FIG.
[0019]
As shown in FIG. 2, an automotive air conditioner 11 according to the present invention has an intake unit 12 for selectively taking in outside air from outside the vehicle or inside air inside the vehicle, and cools air taken in through the intake unit. And a heater unit 14 that adjusts the temperature of the cool air from the cooling unit 13 in harmony with the warm air and then blows the air into the vehicle.
[0020]
At the junction of the outside air intake 15 and the inside air intake 16 provided in the intake unit 12, an intake door 17 for adjusting the ratio of the intake amount of outside air and inside air taken into the inside via the respective intakes 15, 16 is provided. , Are provided so as to be swingable around the pivot 17a. The intake door 17 is operated by an intake door actuator that is driven by an electric motor 18a such as a DC motor, which is an electric door opening / closing control motor. The intake port 15 is rotated between an opening position indicated by reference numeral B and the intake port 15 fully closed.
[0021]
Therefore, as is well known in the art, when the fan motor 19 operates, the outside air introduction mode (FRE) is activated when the intake door 17 is at the opening position A in accordance with the intake negative pressure generated by the rotation of the fan 20. The air is taken into the intake unit 12 from the outside air intake 15 from the outside air intake 15 and from the inside air intake 16 as the inside air circulation mode (REC) when in the opening position B. At an intermediate position between the opening positions A and B, outside air and inside air are introduced into the intake unit 12 from the respective intakes 15 and 16 at a ratio corresponding to the opening position of the intake door 17.
[0022]
The cooling unit 13 is provided with an evaporator 21. When the evaporator 21 receives the supply of the compressed cooling medium from a compressor (not shown) connected thereto, the evaporator 21 cools the intake air from the intake unit 12 by a heat exchange action with the cooling medium.
[0023]
The heater unit 14 is provided with a heater core 22 using, for example, engine cooling water as a heat source. An air mix door 23 is provided in association with the heater core 22. As is well known in the art, the air mixing door 23 has a pivot 23a for adjusting the ratio of the amount of cooling air from the cooling unit 13 that passes through the heater core 22 and the amount that bypasses the heater core 22. The door opening is made variable by the operation of an air-mix door actuator which is driven by an electric motor 18b which is the same electric door opening / closing control motor as described above. By adjusting the opening of the air mix door 23, it is possible to adjust the mixing ratio of the warm air heated by the heater core by passing through the heater core 22 and the cool air from the cooling unit 13 bypassing the heater core 22. it can.
[0024]
The air adjusted to an appropriate temperature by adjusting the mixing ratio can be supplied into the vehicle interior from each of the defrosting outlet 24, the ventilator outlet 25, and the foot outlet 26. Each of the outlets 24, 25 and 26 is provided with a door 27, 28 and 29 for opening and closing the outlet. Although not shown, each of the doors 27, 28, and 29 can be operated by an actuator using an electric motor similar to that described above as a drive source.
[0025]
In the example shown in FIG. 4, each actuator 110 includes an electric motor 18 (18a or 18b), a worm 111 fixed to a rotating shaft of the electric motor, and a reduction gear train 112 (112a, 112b, 112c and 112d) and an actuator lever 13 fixed to the rotation shaft of the final gear 111d, and the actuator lever is connected to the pivot of each door.
[0026]
The actuator operation control device according to the present invention is used to adjust each door opening of the intake door 17 and the air mix door 23. In the illustrated embodiment, an actuator operation control circuit 10 (10a, 10b) for controlling each electric motor 18a, 18b is provided for each of the intake door actuator and the air mix door actuator. The actuator operation control circuit according to the present invention includes all doors 17, 23, 27, 28, and 29, as well as conventionally known separate doors, mode doors, fresh vent doors, and bi-level doors. Can be applied to door control. As is well known, each actuator operation control circuit 10 can perform wireless communication with a main control device 30 for an air conditioner called an AC amplifier.
[0027]
Although not shown, the main control device 30 includes various sensors such as an inside air sensor for detecting the inside temperature of the vehicle, a solar radiation sensor for detecting the amount of solar radiation, an outside air sensor for detecting the outside air temperature, an automatic switch for selecting automatic control, and an inside temperature setting device. The optimum target opening of each of the doors 17 and 23 is calculated based on each signal from the manual switches as described above. The main controller 30 controls each actuator operation control circuit 10 (10a, 10b) to operate each door 17, 23 to its target opening through the respective actuator operation control circuit 10 (10a, 10b). Communicate with them to give the target value of opening.
[0028]
The actuator operation control circuit 10 shown in FIG. 1 is provided for each operation of the opening degree of the intake door 17 or the air mix door 23.
[0029]
Hereinafter, for simplicity of description, the actuator operation control circuit 10 will be described as an actuator operation control circuit 10a for an electric motor 18a that is a drive source of an intake door actuator.
[0030]
The actuator operation control circuit 10 shown in FIG. 1 is provided to feedback-control the opening of the intake door 17 in accordance with a target value of the opening of the intake door 17 given by communication with the main controller 30.
[0031]
The actuator operation control circuit 10 includes a communication unit 31 for communication with the main control device 30, a power supply circuit 32 for obtaining a predetermined voltage power supply for feedback control from the power supply B, and an electric motor for operating the intake door 17. And a control circuit unit 33 for controlling power supply to the motor 18a. The electric motor 18a is incorporated as a drive source in an intake door actuator that operates the intake door 17.
[0032]
The communication unit 31 includes an input / output circuit 34 functioning as an interface for data exchange with the main control device 30, a communication processing circuit 35 for communicating data with the main control device 30 via the input / output circuit, An ID setting circuit 36 for setting a communication identifier for identifying the operation control circuit 10 (10a, 10b). The communication processing circuit 35 identifies data that matches the own identifier set by the ID setting circuit 36 among the data transmitted from the main control device 30, and transmits necessary data to the main control device 30. In the illustrated example, a local interconnect network (LIN) is applied as a communication protocol with the main controller 30.
[0033]
In this embodiment, the control circuit unit 33 includes a drive circuit 37 for operating the electric motor 18a that is a drive source of the actuator of the intake door 17, a drive control circuit 38 that outputs a control signal to the drive circuit, A timer circuit 39 for outputting an operation permission signal to the drive control circuit.
[0034]
Although not shown, the drive circuit 37 can be constituted by a conventionally well-known H-bridge circuit formed by connecting four switching elements such as MOS transistors in an H shape. The drive circuit 37 switches the connection relationship between the pair of power supply terminals of the power supply B and the pair of connection terminals of the electric motor 18a according to a control signal supplied from the drive control circuit 38. In response to the switching operation by the drive circuit 37, the electric motor 18a selects, for example, a stop operation, a forward rotation operation, a reverse rotation operation, or a power generation braking operation when the operation is stopped. In the power generation braking operation, as is well known, the electric motor 18a can function as a power generation brake by grounding a pair of connection terminals of the rotating electric motor 18a.
[0035]
As shown in FIG. 4, a rotating shaft of an electric door opening / closing control motor that is a driving source of the intake door actuator, that is, an electric motor 18a, has a worm 111 and a reduction gear train 112 (112a, 112b, 112c, and 112d) that meshes with the worm. ) And the actuator lever 113, the shaft is connected to the pivot 17a of the intake door 17, whereby the opening of the intake door 17 changes according to the operation of the electric motor 18a. The opening of the intake door 17 is detected by the potentiometer 40 as a voltage value.
[0036]
As is well known, the potentiometer 40 includes a resistor 40a and a slider 40b slidable on the resistor. The DC voltage of the power supply circuit 32 is applied between both ends of the resistor 40a, and the slider 40b slides on the resistor 40a between one end and the other end in accordance with the rotation of the intake door 17. Thus, the voltage corresponding to the opening degree of the intake door 17 can be sequentially extracted from the slider 40b.
[0037]
The voltage value output from the slider 40b of the potentiometer 40, that is, the door opening information, is converted by the A / D conversion circuit 41 into, for example, 8-bit digital data. Due to the conversion into the 8-bit digital data, the door opening of the intake door 17 is displayed stepwise by 256 digital data corresponding to the door opening at every 1/256 angle of the adjustable range. You. The feedback signal converted to the digital data is supplied to a comparator 43 connected to a drive control circuit 38 after passing through a digital filter 42 for removing a noise component.
[0038]
As shown in FIG. 1, the feedback signal can be sent from the communication processing circuit 35 to the main controller 30 as needed.
[0039]
As shown in FIG. 3, the digital filter 42 includes an arithmetic processing circuit 42a, a first storage unit 42b that sequentially stores output data Dx of the arithmetic processing circuit, and digital data output from the A / D conversion circuit 41. Are sequentially stored, and a comparison operation means including a comparator 42d.
[0040]
The comparator 42d compares the digital data Dx stored in the first storage unit 42b with the digital data Dx 'stored in the second storage unit 42c, and determines whether both digital data Dx and Dx' are equal. Alternatively, whether the digital data Dx ′ stored in the second storage unit 42c is larger or smaller than the digital data Dx stored in the first storage unit 42b by one step of the digital value discretized Is determined.
[0041]
Since the slider 40b of the potentiometer 40 slides at a substantially constant speed in accordance with the forward or reverse rotation of the electric motor 18a, the analog output voltage from the potentiometer 40 increases and decreases almost proportionally. Therefore, when the analog voltage does not include noise, the A / D conversion circuit outputs a digital value in which discrete digital data is sequentially increased or decreased by one step.
[0042]
When the digital data Dx 'is continuously output from the A / D conversion circuit 41 to the second storage section 42c of the digital filter 42 while the digital data Dx is being output from the digital filter 42, the comparator 42d outputs the first data. The value of the digital data Dx stored in the storage unit 42b is compared with the value of the digital data Dx 'stored in the second storage unit 42c.
[0043]
For example, when the electric motor 18a is stopped, the value of the digital data output from the A / D conversion circuit 41 does not change, and the values of the digital data Dx and Dx 'stored in the two storage units 42b and 42c are equal. Since the data values are held, the comparator 42d outputs a signal indicating that both data values are equal to the arithmetic processing circuit 42a. The arithmetic processing circuit 42a continues to output the digital data Dx which is the current output as a feedback signal under the situation receiving this signal. This feedback signal indicates that the intake door 17 is kept being held at the door opening corresponding to the digital data Dx.
[0044]
When the digital data Dx 'increases or decreases by one step, that is, by one bit in accordance with the operation of the potentiometer 40 due to the forward or reverse rotation of the electric motor 18a, the comparator 42d determines the magnitude relationship (Dx'> Dx or Dx '<). Dx), the comparison result is output to the arithmetic processing circuit 42a. When the arithmetic processing circuit 42a obtains, from the comparator 42d, a comparison result indicating that the digital data Dx 'is larger than the digital data Dx, the arithmetic processing circuit 42a increases the digital data Dx by one step and converts the digital data into a digital data value (Dx + 1). Output as a feedback signal. Therefore, when the opening of the intake door 17 increases by one step in accordance with the forward rotation of the electric motor 18a, the feedback signal sequentially increases by one step. Similarly, when the opening of the intake door 17 decreases by one step in response to the reverse rotation of the electric motor 18a, the feedback signal sequentially decreases by one step.
[0045]
As a result, in a situation where the digital data output from the A / D conversion circuit 41 does not include noise, the digital filter 42 appropriately uses the digital data from the A / D conversion circuit 41 as a feedback signal to the comparator 43. Output. In the example shown in FIG. 1, the comparator 43 calculates a deviation between a target value stored in a third storage unit 44 described later and a feedback signal from the digital filter 42 for feedback control.
[0046]
By the way, for example, when the resistor 40a of the potentiometer 40 has a partial defect, and the slider 40b of the potentiometer 40 slides on the defective portion, noise may be superimposed on the analog signal from the potentiometer 40. is there. When the signal including such a noise component is output from the A / D conversion circuit 41 to the digital filter 42 and the digital signal Dx ′ including the noise component is stored in the second storage unit 42c of the digital filter 42, the comparison is performed. The data is compared with the digital data Dx stored in the first storage unit 42b by the device 42d. As a result, the comparator 42d outputs the comparison result to the arithmetic processing circuit 42a in accordance with the magnitude relation (Dx '> Dx or Dx'<Dx) similar to the above, but the digital data Dx including a noise component is output. ′ Indicates a digital value larger than the previous digital data Dx by more than two steps, the digital filter 42 merely outputs a digital data value larger by one step at its output end.
[0047]
As described above, according to the digital filter 42, even if the digital data subsequent to a certain digital data includes noise giving a large data value difference exceeding two steps between the two data, the influence of the noise is reduced by one. It is possible to suppress an increase in the data value for each step, and it is possible to reduce the influence of the noise on the feedback signal.
[0048]
In addition, by configuring the digital filter 42 with the arithmetic processing circuit 42a, the two storage units 42b and 42c, and the arithmetic processing circuit 42a, the digital filter 42 can be obtained with a relatively simple configuration at a lower cost and easier than in the past. be able to.
[0049]
In addition, a conventionally well-known up-down counter can be used as the arithmetic processing circuit 42a, whereby the digital filter 42 can be obtained by combining commercially available off-the-shelf products.
[0050]
In the illustrated example, the control circuit unit 33 is connected in series to the third storage unit 44 for temporarily holding target value data output from the communication processing circuit 35, and the third storage unit. And a fourth storage unit 45. Each time the target value sent from the main control device 30 is sent from the communication processing circuit 35, the two storage units 44 and 45 send the target value sent from the communication processing circuit 35 using the clock pulse supplied from the communication processing circuit as a trigger. The data latch circuit sequentially stores the target values to be stored in a first-in first-out manner.
[0051]
The target value output from the communication processing circuit 35 is stored in the third storage unit 44 in response to a trigger from the communication processing circuit 35. Thereafter, when a new target value is output from the communication processing circuit 35, the target value stored in the third storage unit 44 is set to the fourth target value as the previous target value in response to a trigger from the communication processing circuit 35. The data is sent to the storage unit 45 and stored in the storage unit. The new target value output from the communication processing circuit 35 is stored in the third storage unit 44. Thereafter, every time a new target value is output from the communication processing circuit 35, the data stored in the third storage unit 44 is updated with the new target value in response to a trigger from the communication processing circuit 35, and the fourth target value is output. The data stored in the storage unit 45 is updated with the target value stored in the first storage. Therefore, the latest target value from the main controller 30 is stored in the third storage unit 44, and the previous target value is stored in the fourth storage unit 45.
[0052]
The latest target value stored in the third storage unit 44 is sent to the comparator 43. The comparator 43 compares the latest target value from the third storage unit 44 with the feedback signal passing through the digital filter 42, and compares the deviation with the drive control circuit 38 for controlling the operation of the electric motor 18a. Output.
[0053]
As long as the drive control circuit 38 receives the operation permission signal from the timer circuit 39, that is, unless the operation control signal is received from the timer circuit 39, the new control value stored in the third storage unit 44 and the feedback A control signal is output to the drive circuit 37 so as to match the signal value. The drive circuit 37 operates according to a control signal from the drive control circuit 38 to rotate the electric motor 18a forward when, for example, the target value is larger than the feedback signal value, thereby increasing the opening degree of the intake door 17. Alternatively, when the target value is smaller than the feedback signal value, the electric motor 18a is operated to rotate in the reverse direction, whereby the opening of the intake door 17 is reduced.
[0054]
In this feedback control, as described above, since the digital filter 42 reduces the noise component included in the feedback signal, the intake signal is quickly and appropriately adjusted to the target value by the feedback signal in which the noise component is reduced. Receive control toward.
[0055]
In the illustrated embodiment, an overcurrent detection circuit 46 and a drive voltage control circuit 47 for preventing supply of an overcurrent to the electric motor 18a are provided. When an overcurrent to the electric motor 18a is detected by the overcurrent detection circuit 46, the drive control circuit 38 operates the drive circuit 37 to stop supplying power to the electric motor 18a. Further, the drive control circuit 38 receives the control signal from the drive voltage control circuit 47 during braking of the electric motor 18a, and gives a time delay to the operation of the switching element composed of the MOS transistor of the drive circuit 37 so as to give a time delay. Control the gate voltage. Due to this time delay, occurrence of backlash due to sudden braking can be suppressed.
[0056]
When a new target value is stored in the third storage unit 44, the timer circuit 39 that transmits the operation permission signal to the drive control circuit 38, when the new target value is stored in the third storage unit 44, The comparator 48 compares the previous target value stored in the fourth storage unit 45 with the previous target value, and outputs a timer reset signal when the two do not match, and the timer 48 when the timer reset signal is received from the comparator. A timer 49 is provided for continuously outputting the operation permission signal to the drive control circuit 38 for a predetermined time after receiving the reset signal, and stopping the transmission of the operation permission signal when a predetermined time has elapsed.
[0057]
The required time set by the timer 49, that is, the predetermined time for continuously outputting the operation permission signal, is set to the given target opening regardless of the opening position of the intake door 17 by the operation of the ordinary electric motor 18a. The time required to move the intake door 17 and converge the movement to the target opening is set. As the required time, for example, 15 seconds, which is slightly longer than the time required for the slider 40b of the potentiometer 40 to move from one end of the resistor 40a to the other end, is employed as described above.
[0058]
When a new target value is stored in the third storage unit 44, the comparator 48 of the timer circuit 39 stores the target value stored in the third storage unit 44 in the target stored in the fourth storage unit 45. When the value coincides with the value, the timer 49 does not output the timer reset signal.
[0059]
Therefore, for example, when a new target value identical to the previous target value is transmitted from the main control device 30 to the actuator operation control circuit 10, the target values of the third storage unit 44 and the fourth storage unit 45 become Since they match, the comparator 48 does not output a timer reset signal to the timer 49. Therefore, in this case, the operation of the drive control circuit 38 is stopped, and the drive circuit 37 holds the electric motor 18a in a stopped state without operating the electric motor 18a. As a result, the intake door 17 is kept at the opening that matches the previous target value.
[0060]
On the other hand, when a new target value different from the previous target value is transmitted from the main controller 30 to the actuator operation control circuit 10, the comparator 48 of the timer circuit 39 causes the new value stored in the third storage unit 44 to be stored. A mismatch between the desired target value and the previous target value stored in the fourth storage unit 45 is detected, and a timer reset signal is output to the timer 49.
[0061]
Upon receiving the timer reset signal from the comparator 48, the timer 49 outputs an operation permission signal to the drive control circuit 38 for, for example, 15 seconds. The drive control circuit 38 is in an operable state while receiving the operation permission signal. Therefore, in a situation where the overcurrent detection signal from the overcurrent detection circuit 46 is not received, the third drive control circuit 38 operates as described above. The deviation between the target value from the storage unit 44 and the feedback signal output from the potentiometer 40 to the A / D conversion circuit 41 and reduced from the A / D conversion circuit via the digital filter 42 according to the present invention and having reduced noise components is output. The operation of the electric motor 18a is controlled via the drive circuit 37 so that the output of the comparator 43 becomes zero.
[0062]
During the control operation of the actuator operation control circuit 10, for example, a lock state occurs due to a mechanical failure in the electric motor 18a, or the intake door 17 does not converge to the target opening degree for some reason. Even if a hunting phenomenon that causes vibration around the center occurs, the timer 49 stops sending the operation permission signal to the drive control circuit 38 when the predetermined time has elapsed, so that the power supply from the drive circuit 37 to the electric motor 18a is stopped. You.
[0063]
Due to the operation of the timer circuit 39, the overheating due to the lock of the electric motor 18a or the excessive hunting exceeding a predetermined time can be performed without depending on the overheating prevention mechanism of the electric motor 18a and without employing a special duty ratio control program. The phenomenon can be reliably prevented.
[0064]
Although the timer circuit 39 can be omitted, in the automotive air conditioner 11, if the hunting phenomenon described above occurs due to the operation of the intake door 17, the abnormal noise caused by the hunting phenomenon causes a noise in the vehicle. Therefore, by providing the timer circuit 39, an excessive hunting phenomenon in the air conditioner can be prevented. Therefore, it is desirable to provide the timer circuit 39 in order to reduce in-vehicle noise due to the hunting phenomenon.
[0065]
Regarding the required time set by the timer circuit 39, the normal operation of the electric motor 18a moves the intake door 17 to the given target opening regardless of the opening position of the intake door 17, The time required to converge the exercise to the target opening can be appropriately selected.
[0066]
Instead of the intake door 17, an actuator operation control circuit 10 similar to that shown in FIG. 1 can be applied to the operation control of the electric motor 18b of the air mix door 23, and if necessary, the doors 27 to 29 and others can be used. The actuator operation control circuit can also be applied to the door operation control.
[0067]
Further, the actuator operation control circuit can be applied to a wired operation control circuit in addition to the above-described wireless system.
[0068]
In the above description, the digital filter according to the present invention has been described along with an example in which the digital filter is incorporated in an actuator operation control device provided with a drive control circuit 38 that operates in response to an operation permission signal from a timer circuit 39. Instead, the digital filter according to the present invention can be applied to an actuator operation control device provided with a drive control circuit that is not controlled by the timer circuit 39, whereby the noise component included in the feedback signal can be reduced. Since the influence can be effectively reduced, appropriate feedback control can be performed.
[0069]
【The invention's effect】
According to the first aspect of the present invention, the comparison operation means compares the output data with the digital data from the A / D conversion circuit, and the digital data has increased or decreased in two or more steps due to noise components. However, since digital data indicating one step of increase or decrease is output according to the comparison result, a digital signal in which the influence of noise is suppressed can be obtained.
[0070]
According to the second aspect of the present invention, the comparison operation means can be composed of two storage units, a comparator and an operation processing circuit, whereby the present invention can be implemented relatively inexpensively and easily.
[0071]
According to the third aspect of the present invention, the arithmetic processing circuit can be constituted by an up / down counter, whereby the digital filter of the present invention can be realized by a combination of commercially available off-the-shelf products.
[0072]
According to the inventions set forth in claims 4 and 5, the influence of noise can be substantially eliminated from the operation control of the door opening / closing control motor that operates the door of the air conditioner for a vehicle, whereby proper air conditioning can be achieved. Thereby, a comfortable in-vehicle environment can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a control circuit incorporating a digital filter according to the present invention.
FIG. 2 is a sectional view schematically showing an example of a vehicle air conditioner controlled by a control circuit shown in FIG. 1;
FIG. 3 is a block diagram showing an electric circuit of the digital filter according to the present invention.
FIG. 4 is a structural diagram showing an internal configuration of an actuator according to the present invention.
[Explanation of symbols]
10. Actuator operation control circuit (actuator operation control device)
11 Automotive air conditioner 18 (18a, 18b) Actuator drive source (electric motor)
40 potentiometer 41 A / D conversion circuit 42 digital filter (comparison operation means)
42a arithmetic processing circuit 42b first storage unit 42c second storage unit 42d comparator

Claims (5)

An analog feedback signal output from the potentiometer is sequentially digitized in order to digitally control the operation of the drive source of the actuator based on a comparison between a target value of the actuator and a feedback signal value from a potentiometer for detecting the operating position of the actuator. A digital filter connected to an A / D conversion circuit for reducing noise of digital data output from the A / D conversion circuit, comprising a comparison operation means, wherein the comparison operation means The digital data output from the A / D conversion circuit is compared with the digital data output from the / D conversion circuit, and the digital data output from the A / D conversion circuit is equal to the output data to be compared with the digital data. Digital data that is one step larger than data or digital that is one step smaller And outputting either data selectively, digital filter for actuator operation control device. The comparison operation means includes an operation processing circuit, a first storage unit for storing digital data output from the operation processing circuit, and a second storage unit for storing digital data output from the A / D conversion circuit. And a comparator for comparing the two digital data stored in the first and second storage units, wherein the arithmetic processing circuit is configured to perform the first operation when the comparison result obtained by the comparator is equal. And outputting the digital data stored in the first storage unit when the digital data stored in the first storage unit is larger than the digital data stored in the second storage unit. It outputs digital data one step smaller than the digital data, and stores the digital data in the first storage unit when the digital data stored in the first storage unit is smaller than the digital data stored in the second storage unit. Digital filter according to claim 1, wherein the outputting the first stage large digital data than the digital data. 3. The digital filter according to claim 2, wherein said arithmetic processing circuit comprises an up / down counter. The digital filter according to claim 1, wherein the drive source is an electric door opening / closing control motor of an air conditioner for a vehicle. The digital filter according to claim 4, wherein the electric door opening / closing control motor operates each door provided in the air conditioner.

Images