JP5380080B2 - Wiper drive device for vehicle - Google Patents

Description

  The present invention relates to a vehicle wiper driving device that drives a wiper attached to a windshield or a rear glass.

  Conventionally, as a problem when driving a wiper attached to a windshield or rear glass, the wiper cannot move to an upper limit position or a lower limit position due to snow or mud accumulated near the pillar or louver (hereinafter, this state is referred to as “ The wiper is restrained "). For example, if the wiper is restrained near the upper part of the windshield, even if it tries to move the wiper further upward, a load is generated on the drive motor etc., and when the wiper stops, the area below the restrained position Also, it will rain and snow. Therefore, when the wiper is restrained, it is desirable to quickly reverse the wiper drive direction.

  The invention about the apparatus which considered the point concerned is indicated (for example, refer to patent documents 1). In this apparatus, when an overcurrent of a motor for driving the wiper is detected, the driving direction of the wiper is reversed.

Japanese Patent No. 2503970

  The conventional apparatus is configured to compare a voltage drop at a predetermined point in the circuit configuration with a certain threshold value and to determine that an overcurrent has flowed through the motor when the threshold value is exceeded.

  However, the value of the current flowing through the motor when the wiper is restrained (the voltage value is used in the above-described conventional device) varies depending on various factors. Therefore, when the overcurrent is detected using a certain threshold value as in the above-described conventional apparatus, it may be overlooked that the wiper is restrained or erroneously detected.

  The present invention is for solving such a problem, and provides a vehicle wiper drive device capable of more accurately recognizing that the wiper is restrained and performing reversal control of the wiper. Main purpose.

In order to achieve the above object, one embodiment of the present invention provides:
A motor that drives the wiper in both directions;
Motor current detecting means for detecting a current flowing through the motor;
A vehicle wiper device comprising: control means for controlling the motor such that the driving direction of the motor is reversed when the current detected by the motor current detection means exceeds a threshold value;
Supply voltage detection means for detecting the voltage supplied to the motor,
The control means changes the threshold value so that the threshold value decreases as the voltage detected by the supply voltage detection means decreases ,
A temperature detecting means for detecting the temperature of the motor;
The control means changes the threshold value so that the threshold value decreases as the temperature detected by the temperature detection means increases.
It is a wiper drive device for vehicles.

  According to this aspect of the present invention, it is possible to flexibly cope with a decrease in current when the wiper is restrained due to a decrease in voltage supplied to the motor. Accordingly, it is possible to suppress inconvenience that the wiper is restrained or erroneously detected. As a result, it is possible to more accurately recognize that the wiper is restrained and to perform the wiper reversal control.

Further , it is possible to flexibly cope with a decrease in current when the wiper is restrained due to a decrease in voltage supplied to the motor and a temperature increase in the motor. Accordingly, it is possible to suppress inconvenience that the wiper is restrained or erroneously detected. As a result, it is possible to more accurately recognize that the wiper is restrained and to perform the wiper reversal control.

  ADVANTAGE OF THE INVENTION According to this invention, the wiper drive device for vehicles which can recognize more correctly that the wiper was restrained and can perform the inversion control of a wiper can be provided.

1 is a system configuration example of a vehicle wiper drive device 1 according to a first embodiment of the present invention. It is the figure which illustrated the relationship between the supply voltage Vb and threshold value Ix in 1st Example. It is an example of the flowchart which shows the flow of the process performed by the control part 40 which concerns on 1st Example. It is a system structural example of the wiper drive device 2 for vehicles which concerns on 2nd Example of this invention. It is the figure which illustrated the relationship between temperature T and supply voltage Vb, and threshold value Ix in 2nd Example. It is an example of the flowchart which shows the flow of the process performed by the control part 40 which concerns on 2nd Example.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

<First embodiment>
Hereinafter, a vehicle wiper drive device 1 according to a first embodiment of the present invention will be described. FIG. 1 is a system configuration example of a vehicle wiper drive device 1 according to a first embodiment of the present invention. The vehicle wiper drive device 1 includes, as main components, a power supply 10, a power supply voltage monitoring circuit 20, a motor 30 and a motor drive circuit 32, a motor current detection circuit 34, a control unit 40, a wiper switch 50, And an input circuit 52.

  The power source 10 is a secondary battery such as a lead storage battery. Instead of this, a switching power supply device or the like may be used as the power supply 10.

  The power supply voltage monitoring circuit 20 is attached by branching from a power line (which may include the internal wiring of the motor 30 and the motor drive circuit 32) for supplying power from the power supply 10 to the motor 30, and has a detection resistor and the like. The power supply voltage monitoring circuit 20 detects the specific potential with respect to ground (= the supply voltage Vb of the power supply 10) at the branch point and outputs it to the control unit 40.

  The motor 30 is, for example, a known DC motor, and its output shaft is connected to a drive mechanism for driving a wiper of the vehicle. Although there is no particular limitation on the specific mode of the drive mechanism, for example, it has a mechanism for increasing or decreasing the rotation of the output shaft of the motor 30, a stopper for stopping the wiper at the movement limit point of the wiper, and the like.

  The motor drive circuit 32 is an H bridge circuit having, for example, four bridge semiconductor switching elements (such as MOS transistors) arranged in an H bridge shape. The motor driving circuit 32 applies electric power having different polarities to the motor 30 by being controlled so that the opposing semiconductor switching elements for bridges are simultaneously turned on, whereby the motor driving circuit 32 causes the motor 30 to It can be driven in both directions.

  The motor current detection circuit 34 includes a detection resistor connected in series in the middle of a power line (including the internal wiring of the motor 30 and the motor drive circuit 32) for supplying power from the power supply 10 to the motor 30, and a detection A voltage sensor for detecting the voltage across the resistor. The motor current detection circuit 34 outputs the voltage signal thus detected (voltage signal indicating the current I flowing through the motor 30; hereinafter simply referred to as current I) to the control unit 40.

  The control unit 40 is, for example, a microcomputer in which a ROM (Read Only Memory), a RAM (Random Access Memory), and the like are connected to each other via a bus with a CPU (Central Processing Unit) as a center, and other temporary storage devices And I / O ports, timers, counters, etc. The ROM stores programs and data executed by the CPU.

  An input signal from the wiper switch 50 is input to the control unit 40 via the input circuit 52. The control unit 40 controls the motor drive circuit 32 to drive the motor 30 bidirectionally when the wiper switch 50 is turned on by a driver's operation.

  Further, when the controller 40 detects an overcurrent of the motor 30, the control unit 40 changes the set of bridge semiconductor switching elements to be turned on in the motor drive circuit 32 and reverses the polarity of the power applied to the motor 30, Control to reverse the driving direction of the motor 30, that is, the driving direction of the wiper is performed.

  In the present embodiment, whether or not an overcurrent of the motor 30 has occurred is determined by whether or not the current I input from the motor current detection circuit 34 exceeds the threshold value Ix.

  As described above, the overcurrent of the motor 30 occurs when the wiper cannot move to the upper limit position or the lower limit position due to snow or mud accumulated near the pillar or louver, that is, when the wiper is restrained. When the wiper is restrained, it is desirable to quickly reverse the driving direction of the wiper.

  However, the current flowing through the motor 30 when the wiper is restrained varies depending on the voltage supplied from the power supply 10 to the motor 30. Accordingly, when it is determined whether or not an overcurrent has occurred in the motor 30 using a certain threshold value, it may be overlooked that the wiper is restrained or erroneously detected.

  Therefore, in the control unit 40 according to the present embodiment, the threshold value Ix is changed so that the threshold value Ix decreases as the supply voltage Vb of the power supply 10 detected by the power supply voltage monitoring circuit 20 decreases.

  FIG. 2 is a diagram illustrating the relationship between the supply voltage Vb and the threshold value Ix in the first embodiment. In the figure, for example, when the power supply 10 supplies a voltage of 12 [V] during normal operation, the reference voltage V1 is set to about 11 [V] when the power supply performance of the power supply 10 starts to decrease. Such a relationship may be stored in advance as a map in the ROM of the control unit 40 or may be derived by a function. The following equation (1) expresses such a relationship with a mathematical expression.

Ix = α (Vb ≧ V1),
= Α−β (V1−Vb) (Vb <V1) (1)

  The value α of the constant portion in the threshold value Ix is a value corresponding to the temperature limit value of the motor 30 (temperature limit value when the motor 30 generates heat with normal use of the motor 30; for example, about 100 to 120 degrees Celsius) Tmax. It is stipulated in. Here, when the motor 30 generates heat, the resistance value of the internal wiring of the motor 30 and the motor drive circuit 32 increases, so that the current flowing through the motor 30 when the overcurrent is generated in the motor 30 (current when the wiper is restrained) decreases. Will be. Therefore, the wiper restraint current is larger than the voltage when the supply voltage Vb is equal to or higher than the voltage A and the temperature of the motor 30 is the temperature limit value Tmax so that the restraint of the wiper can be properly detected even when the motor 30 generates heat. The value α is set to a slightly lower value. The value β in the equation (1) indicates the inclination of the inclined portion of the threshold value Ix.

  FIG. 3 is an example of a flowchart showing a flow of processing executed by the control unit 40 according to the first embodiment. The control unit 40 repeatedly executes such processing every predetermined time.

  First, it is determined whether or not the supply voltage Vb is equal to or higher than the reference voltage V1 (S100).

  When the supply voltage Vb is equal to or higher than the reference voltage V1, the value α is set to the threshold value Ix (S102).

  On the other hand, when the supply voltage Vb is less than the reference voltage V1, the value {α−β (V1−Vb)} is set to the threshold value Ix (S104).

  Then, using the set threshold value Ix, it is determined whether or not the current I exceeds the threshold value Ix (S106). When it is determined that the current I exceeds the threshold value Ix, the driving direction of the wiper is reversed (S108). The processing of S106 and S108 may be performed in parallel by a flow different from the processing of S100 to S104.

  Detailed description of the reversing control of the driving direction of the wiper when there is no obstacle to the driving of the wiper will be omitted. However, it may be detected by some means that the wiper has moved to the limit point. The same process as the reversal control when the wiper is constrained may be performed by utilizing the fact that the wiper is constrained by the movement.

  According to the vehicle wiper drive device 1 of the present embodiment described above, it is possible to flexibly cope with a decrease in current when the wiper is restrained due to a decrease in the supply voltage Vb of the power supply 10. Accordingly, it is possible to suppress inconvenience that the wiper is restrained or erroneously detected. As a result, it is possible to more accurately recognize that the wiper is restrained and perform the wiper reversal control.

<Second embodiment>
Hereinafter, a vehicle wiper drive device 2 according to a second embodiment of the present invention will be described. FIG. 4 is a system configuration example of the vehicle wiper drive device 2 according to the second embodiment of the present invention. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, detailed description thereof will be omitted, and differences will be mainly described.

  The vehicle wiper drive device 2 includes a temperature detection circuit 60 in addition to the configuration of the vehicle wiper drive device 1 according to the first embodiment.

  The temperature detection circuit 60 is a circuit for detecting the temperature of the motor 30. When components other than the motor 30 are disposed in the same housing as the motor 30, they may be mounted on the substrate of the control unit 40. The temperature T detected by the temperature detection circuit 60 is output to the control unit 40.

  Similar to the first embodiment, the control unit 40 according to the present embodiment changes the threshold value Ix according to the supply voltage Vb of the power supply 10 detected by the power supply voltage monitoring circuit 20, and the temperature detection circuit 60. The threshold value Ix is changed in accordance with the temperature T input from.

  FIG. 5 is a diagram illustrating the relationship among the temperature T, the supply voltage Vb, and the threshold value Ix in the second embodiment. As illustrated, in the control unit 40 according to the present embodiment, the temperature detection circuit 60 is configured such that the threshold value Ix decreases as the supply voltage Vb of the power supply 10 detected by the power supply voltage monitoring circuit 20 decreases. The threshold value Ix is changed so that the threshold value Ix decreases as the temperature T input from is increased.

  FIG. 6 is an example of a flowchart showing a flow of processing executed by the control unit 40 according to the first embodiment. The control unit 40 repeatedly executes such processing every predetermined time.

  First, it is determined whether or not the supply voltage Vb is equal to or higher than the reference voltage V1 (S200).

  If the supply voltage Vb is equal to or higher than the reference voltage V1, the value α is set to the threshold value Ix (S202).

  On the other hand, when the supply voltage Vb is less than the reference voltage V1, the value {α−β (V1−Vb)} is set to the threshold value Ix (S204).

  Subsequently, it is determined whether or not the temperature T is within a first temperature range (for example, a range of 20 degrees Celsius or less) (S206). If it is within the first temperature range, the threshold Ix is reset by multiplying the threshold Ix by the multiplier W1 (W1> 1) (S208).

  If the temperature T is not within the first temperature range, it is determined whether or not the temperature T is within the second temperature range (for example, a range of 20 degrees Celsius to 40 degrees Celsius) (S210). If it is within the second temperature range, the threshold Ix is reset by multiplying the threshold Ix by a multiplier W2 (W1> W2> 1) (S212).

  If the temperature T is not within the second temperature range, it is determined whether or not the temperature T is within a third temperature range (for example, a range of 40 degrees Celsius to 70 degrees Celsius) (S214). If it is within the second temperature range, the threshold value Ix is multiplied by the multiplier W3 (W2> W3> 1) to reset the threshold value Ix (S216).

  If the temperature T is not within the third temperature range, the threshold value Ix set in S200 to S204 is used as it is.

  Then, using the set threshold value Ix, it is determined whether or not the current I exceeds the threshold value Ix (S218). When it is determined that the current I exceeds the threshold value Ix, the wiper drive direction is reversed (S220). The processing of S218 and S220 may be performed in parallel by a flow different from the processing of S200 to S216.

  According to the vehicle wiper drive device 2 of the present embodiment described above, it is possible to flexibly cope with a decrease in current when the wiper is restrained due to a decrease in the supply voltage Vb of the power supply 10 or a temperature increase of the motor 30. Accordingly, it is possible to suppress inconvenience that the wiper is restrained or erroneously detected. As a result, it is possible to more accurately recognize that the wiper is restrained and perform the wiper reversal control.

  The best mode for carrying out the present invention has been described above with reference to the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the scope of the present invention. And substitutions can be added.

  The present invention can be used in the automobile manufacturing industry, the automobile parts manufacturing industry, and the like.

DESCRIPTION OF SYMBOLS 1, 2 Vehicle wiper drive device 10 Power supply 20 Power supply voltage monitoring circuit 30 Motor 32 Motor drive circuit 34 Motor current detection circuit 40 Control part 50 Wiper switch 52 Input circuit 60 Temperature detection circuit

Claims (1)

A motor that drives the wiper in both directions;
Motor current detecting means for detecting a current flowing through the motor;
A vehicle wiper device comprising: control means for controlling the motor such that the driving direction of the motor is reversed when the current detected by the motor current detection means exceeds a threshold value;
Supply voltage detection means for detecting the voltage supplied to the motor,
The control means changes the threshold value so that the threshold value decreases as the voltage detected by the supply voltage detection means decreases ,
A temperature detecting means for detecting the temperature of the motor;
The control means changes the threshold value so that the threshold value decreases as the temperature detected by the temperature detection means increases.
A wiper driving device for a vehicle.

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