Patent Description:
A WWS is typically employed on a vehicle, such as an aircraft, to clear moisture or foreign object debris from a windshield and to allow for improved visibility. For example, a WWS on an aircraft can be used to improve visibility for pilots or co-pilots during take-off or landing operations.

To ensure that a WWS provides for required coverage on a windshield, the WWS will generally be designed to move through a specific wipe or sweep angle. This sweep angle can be controlled with or without a four bar mechanism designed to configured the WWS to sweep through the specific angle and return to a park position. The WWS is not typically expected to have any movement or flutter when it is non-operational under all loading conditions. <CIT> describes a brushless motor and wiper apparatus. <CIT> describes a reversing motor windshield wiper system.

A windshield wiper system (WWS) is described herein and defined in claim <NUM>.

In accordance with additional or alternative embodiments, the wiper blade assembly is configured to move across a windshield of a vehicle and includes a wiper arm and a wiper blade attached to the wiper arm.

In accordance with additional or alternative embodiments, the WWS further includes a motor, which is operable by a motor drive control signal output from the controller, and a mechanical gear train and four bar linkage operably interposed between the motor and the wiper blade assembly. The controller is configured to control the driving of the wiper blade assembly in accordance with the sweep angle feedback signal and in accordance with position, current and temperature feedback signals derived from the motor.

In accordance with additional or alternative embodiments, the internal wiper trigger is coupled to the wiper blade assembly.

In accordance with additional or alternative embodiments, the internal wiper trigger generates a magnetic field and the measurement system is responsive to the magnetic field to monitor the position of the internal wiper trigger.

In accordance with additional or alternative embodiments, the measurement system includes Hall Effect sensors positioned proximate to opposite ends of the second sweep angle and the Hall Effect sensors are configured to generate a variable duty cycle output responsive to the magnetic field and to issue the variable duty cycle output to the controller as the sweep angle feedback signal.

According to another aspect of the disclosure, a windshield wiper system (WWS) is provided and includes a wiper blade assembly drivable along a first sweep angle, an internal wiper trigger disposed to move with the wiper blade assembly and along a second sweep angle corresponding to the first sweep angle, a measurement system configured to monitor a position of the internal wiper trigger relative to the second sweep angle from which a corresponding position of the wiper blade assembly relative to the first sweep angle is measurable and to output a sweep angle feedback signal corresponding to monitoring results and a controller. The controller is receptive of the sweep angle feedback signal.

In accordance with additional or alternative embodiments, the controller is configured to control a driving of the wiper blade assembly in accordance with at least the sweep angle feedback signal.

In accordance with additional or alternative embodiments, the second sweep angle is a same sweep angle as the first sweep angle.

In accordance with additional or alternative embodiments, the internal wiper trigger generates a magnetic field and the measurement system is responsive to the magnetic field to monitor the position of the internal wiper trigger relative to the second sweep angle.

According to another aspect of the disclosure, a method of operating a windshield wiper system (WWS) is provided. The method includes driving a wiper blade assembly along a first sweep angle by a controller, monitoring a position of an internal wiper trigger disposed to move with the wiper blade assembly from which a corresponding position of the wiper blade assembly relative to the first sweep angle is measurable, outputting a sweep angle feedback signal corresponding to results of the monitoring to the controller and controlling the driving of the wiper blade assembly by the controller in accordance with at least the sweep angle feedback signal.

In accordance with additional or alternative embodiments, the controlling of the driving of the wiper blade assembly by the controller is executed in accordance with the sweep angle feedback signal and in accordance with motor position, motor current and motor temperature feedback signals.

In accordance with additional or alternative embodiments, the monitoring includes generating a magnetic field at an internal wiper trigger disposed to move with the wiper blade assembly and generating a variable duty cycle output responsive to the magnetic field for issuance to the controller as the sweep angle feedback signal.

In accordance with additional or alternative embodiments, the sweep angle feedback signal has a negligible parallax error.

In accordance with additional or alternative embodiments, the method further includes at least one of in-flight gear and shaft and real-time sweep angle monitoring based on the sweep angle feedback signal, computing a speed of a motor configured to drive the wiper blade assembly and facilitating an identification of ageing issues or failures of the motor, the wiper blade assembly or a gear train interposed between the motor and the wiper blade assembly.

A conventional WWS can include an intelligent device with a controller or processor that provides a motor commutation sequence and monitors system faults, an internal wiper trigger that detects an end of sweep position of an external wiper blade, a park sensor feedback system with an end of sweep (EoS) sensor that detects the end of sweep position of the WWS by monitoring the internal wiper trigger, Hall sensor feedback to measure a speed of a motor of the WWS, motor current feedback to monitor motor winding currents, motor winding temperature feedback to monitor temperatures of the motor windings, a mechanical gear train and four bar link mechanism and a wiper arm and blade. The mechanical gear train and the four bar link mechanism converts rotary motion of the motor to oscillatory motion and the wiper arm and blade is driven by the oscillatory motion to wipe the windshield.

Thus, in the conventional WWS, it is seen that Hall sensors are used to detect a speed of the motor. As such, any disconnections in Hall sensor signal lines can lead to system failures. In addition, the conventional WWS can include a worm gear that acts as a mechanical brake and a failure of the worm gear teeth can lead to an undesirable movement of the WWS from a park position. The conventional WWS does not have mechanism to detect this movement due to worm gear failure or other mechanical failures. That is, in the conventional WWS, Hall sensors are used for motor speed measurement but Hall sensors measure the speed only at motor ends and do not account for losses or faults in the mechanical gear train.

As will be described below, a WWS is provided and configured with a capability of measuring a sweep angle of wiper blades by continuously monitoring a sweep angle of an internal wiper trigger. The continuous monitoring of the sweep angle is accomplished by way of strategically placed pulse width modulation (PWM) output linear Hall Effect sensors inside a wiper module. Thus, while a conventional WWS can be characterized in that the internal wiper trigger is used only to detect an EoS of external wiper blades, the internal wiper trigger experiences same external loads as that of the external wiper blades and this internal wiper trigger can be leveraged for sweep angle measurement of the external wiper blades as both the internal wiper trigger and the external wiper blades have the same sweep angle.

With reference to <FIG>, a windshield wiper system (WWS) <NUM> is provided for use with an airframe <NUM>, such as an airframe of a vehicle or an aircraft. The airframe <NUM> is supportive of a windshield <NUM>. The WWS <NUM> includes a wiper blade assembly <NUM> and an internal control assembly <NUM> (see <FIG>). The wiper blade assembly <NUM> includes a wiper arm <NUM> and a wiper blade <NUM>. The wiper blade <NUM> is attached to a distal end of the wiper arm <NUM> and is biased toward and onto the windshield <NUM> by the wiper arm <NUM>. The wiper blade assembly <NUM> is configured to assume a parked position relative to the windshield <NUM> unless a pilot/copilot command is entered to initiate a driving of the wiper blade assembly <NUM> whereby the wiper blade <NUM> moves across the windshield <NUM> along a first sweep angle α1. The internal control assembly <NUM> is configured to drive the wiper blade assembly <NUM> across the windshield <NUM> along the first sweep angle α1 such that the wiper blade element moves across the windshield <NUM> to remove moisture or foreign object debris from the windshield <NUM>.

As shown in <FIG> and <FIG>, the WWS <NUM> further includes an internal wiper trigger <NUM> and a measurement system <NUM>.

The internal wiper trigger <NUM> is disposed to move with the wiper blade assembly <NUM> and along a second sweep angle α2 (see <FIG>) that corresponds to the first sweep angle α1. In accordance with embodiments, the internal wiper trigger <NUM> can be coupled to the wiper arm <NUM> or another suitable component of the wiper blade assembly <NUM> (i.e., an output shaft leading to the wiper arm <NUM>) and is configured to generate a magnetic field. As a result of being coupled to the wiper arm <NUM> or another suitable component of the wiper blade assembly <NUM>, the internal wiper trigger <NUM> experiences a same or similar loading as the wiper blade assembly <NUM>.

Since the internal wiper trigger <NUM> is coupled to the wiper arm <NUM> or another suitable component of the wiper blade assembly <NUM>, the second sweep angle α2 is a same sweep angle as the first sweep angle α1.

The measurement system <NUM> is configured to monitor a position of the internal wiper trigger <NUM> relative to the second sweep angle α2 from which a corresponding position of the wiper blade assembly <NUM> relative to the first sweep angle α1 is measurable. The measurement system <NUM> is further configured to output a sweep angle feedback signal SAFS, which corresponds to monitoring results, to the internal control assembly <NUM>. In accordance with embodiments, the measurement system <NUM> can include Hall Effect sensors <NUM>. As shown in <FIG>, the Hall Effect sensors <NUM> can be disposed at opposite sides of an output shaft leading to the wiper blade assembly <NUM> or, more particularly, to the wiper arm <NUM> and are responsive to the magnetic field generated by the internal wiper trigger <NUM>. As such, the Hall Effect sensors <NUM> generate a variable duty cycle output that corresponds to the interaction between the Hall Effect sensors <NUM> and the internal wiper blade trigger <NUM> (as will be discussed below) and issue the variable duty cycle output to the internal control assembly <NUM> as the SAFS.

As shown in <FIG>, the internal control assembly <NUM> includes a controller <NUM>, a motor <NUM> and a mechanical gear train and four bar linkage <NUM>. The controller <NUM> is receptive of the sweep angle feedback signal SAFS and is configured to control a driving of the wiper blade assembly <NUM>. The motor <NUM> can include or be provided as a brushless DC (BLDC) motor and is operable by a motor drive control signal MDCS that is output from the controller <NUM>. The mechanical gear train and four bar linkage <NUM> is operably interposed between the motor <NUM> and the wiper blade assembly <NUM>. The internal control assembly <NUM> further includes a position feedback loop <NUM>, which generates a position error signal PES for reception by the controller <NUM>, a motor current feedback loop <NUM>, which generates a current error signal CES for reception by the controller <NUM>, and a motor winding temperature feedback loop <NUM>, which generates a motor winding temperature error signal MWTES for reception by the controller <NUM>. The position feedback loop <NUM>, the motor current feedback loop <NUM> and the motor winding temperature feedback loop <NUM> are configured in parallel with each other and the position error signal PES, the current error signal CES and the motor winding temperature error signal MWTES are each derived from the motor <NUM>. The controller <NUM> is configured to control the driving of the wiper blade assembly <NUM> in accordance with at least the sweep angle feedback signal SAFS and, more particularly, the controller <NUM> is configured to control the driving of the wiper blade assembly <NUM> in accordance with the sweep angle feedback signal SAFS and in accordance with the position error signal PES, the current error signal CES and the motor winding temperature error signal MWTES.

With continued reference to <FIG> and with additional reference to <FIG> and <FIG>, an output of the Hall Effect sensors <NUM> will be a variable duty cycle PWM output whose duty cycle is proportional to the magnetic flux density as shown in <FIG>. This PWM output can be interfaced directly to a GPIO pin of the controller <NUM> which, on receiving the PWM data, computes the second sweep angle α2 of the internal wiper trigger <NUM>. On extrapolating this data for the actual lengths of the wiper blade assembly <NUM>, the controller <NUM> can compute the first sweep angle α1 as well as a position of the wiper blade <NUM>.

The information computed by the controller <NUM> can be communicated to a pilot or co-pilot over a communication interface. If the first sweep angle α1 is found to be deviating from a required specification and/or if a deviated sweep angle could obstruct the visibility of pilots, then an alarm or maintenance message could be communicated to replace the WWS <NUM> immediately.

The Hall Effect sensors <NUM> can include or be provided as linear Hall Effect sensors and can be placed perpendicular to the magnetic field produced by the internal wiper trigger <NUM>. The generated analog voltage is provided by the following equation: <MAT> Where VH = output voltage of hall sensor proportional to the magnetic field change, RH = Hall effect co-efficient, I = Current flow through the sensor, t = thickness of sensor in mm and B = Magnetic flux density in Tesla.

The PWM output voltage generated is calibrated and interfaced with the controller <NUM>. The duty cycle of the output voltage is directly proportional to the second sweep angle α2. Hence by this approach, the first sweep angle α1 is effectively computed instead of discrete EoS signals of conventional WWSs.

The PWM output of the Hall Effect sensors <NUM> can be interfaced to GPIO pins of the controller <NUM> as shown in <FIG>. The PWM output helps in eliminating errors due to noisy environments in the measurement system <NUM>. Since the duty cycle is directly proportional to the magnetic flux density around the Hall Effect sensors <NUM>, it is seen that the strength of the magnetic flux density around the Hall Effect sensors <NUM> is directly proportional to the second sweep angle α2 of the internal wiper trigger <NUM> (where 'n' of <FIG> represents the second sweep angle α2 of the internal wiper trigger <NUM> from a specific defined position).

With reference to <FIG>, a method of operating the WWS <NUM> is provided. As shown in <FIG>, the method includes driving a wiper blade assembly along a first sweep angle by a controller (<NUM>), monitoring a position of an internal wiper trigger disposed to move with the wiper blade assembly from which a corresponding position of the wiper blade assembly relative to the first sweep angle is measurable (<NUM>), outputting a sweep angle feedback signal corresponding to results of the monitoring to the controller (<NUM>) and controlling the driving of the wiper blade assembly by the controller in accordance with at least the sweep angle feedback signal (<NUM>). The controlling of the driving of the wiper blade assembly by the controller of operation <NUM> can be executed in accordance with the sweep angle feedback signal SAFS and in accordance with the position error signal PES, the current error signal CES and the motor winding temperature error signal MWTES. The monitoring of operation <NUM> can include generating a magnetic field at an internal wiper trigger disposed to move with the wiper blade assembly and generating a variable duty cycle output responsive to the magnetic field for issuance to the controller as the sweep angle feedback signal.

In accordance with embodiments, the sweep angle feedback signal has a negligible parallax error. In addition, the method further includes at least one of in-flight gear and shaft and real-time sweep angle monitoring based on the sweep angle feedback signal by the controller <NUM>, computing a speed of a motor configured to drive the wiper blade assembly by the controller <NUM> and facilitating an identification by an operator of ageing issues or failures of the motor, the wiper blade assembly or a gear train interposed between the motor and the wiper blade assembly.

Claim 1:
A windshield wiper system "WWS" (<NUM>), comprising:
a wiper blade assembly (<NUM>) drivable along a first sweep angle; wherein the wiper blade assembly is configured to move across a windshield of a vehicle and comprises a wiper arm and a wiper blade attached to the wiper arm;
an internal wiper trigger (<NUM>) coupled to the wiper blade assembly and disposed to move with the wiper blade assembly along a second sweep angle which is the same as the first sweep angle; the windshield wiper system (<NUM>) being characterised in that it further comprises a measurement system comprising Hall effect sensors positioned proximate to opposite ends of the second sweep angle and configured to monitor a position of the internal wiper trigger (<NUM>) from which a corresponding position of the wiper blade assembly relative to the first sweep angle is measurable and to output a sweep angle feedback signal corresponding to monitoring results; and
a controller (<NUM>) receptive of the sweep angle feedback signal, and configured to control a driving of the wiper blade assembly in accordance with at least the sweep angle feedback signal,
wherein:
the internal wiper trigger generates a magnetic field and the measurement system is responsive to the magnetic field to monitor the position of the internal wiper trigger relative to the second sweep angle,
the Hall Effect sensors are configured to generate a variable duty cycle output responsive to the magnetic field and to issue the variable duty cycle output to the controller as the sweep angle feedback signal.