INTERMITTENT WINDSHIELD WIPER SYSTEM WITH ELECTRODYNAMIC BRAKING

• US 3,582,747 A
• Filed: 05/23/1968
• Issued: 06/01/1971
• Est. Priority Date: 05/23/1968
• Status: Expired due to Term

• Current Assignee: Robert W. Kearns
• Original Assignee: Robert W. Kearns
• Inventors: Kearns, Robert W.
• Application Number:
  US04/731,531
• Time in Patent Office: 1,104 Days
• US Class Current: 318/379
• CPC Class Codes: B60S 1/0807 using electronic control means, e.g. tubes, semiconductors B60S1/0818, B60S1/0896 take precedence
• CPC Class Codes: H02P 3/12 by short-circuit or resistive braking

Abstract

This specification discloses an intermittent automotive windshield wiper system in which windshield wipers are driven in repeating wiping cycles, stopping for a dwell period at the end of each wiping cycle. The windshield wipers are driven by an electric motor having a permanent magnet field and the wipers are electrodynamically braked to a stop at the end of each wiping cycle. An automatic switch is provided to, in effect, assure that the braking circuit is open at the end of each dwell period when the motor armature is again energized so that DC power is not applied to the braking circuit in parallel with the motor armature at the end of each dwell period.

Claims

1. In a motor system for driving an output intermittently having an electric motor for driving said output and circuit means for energizing said motor to drive said output in steps, stopping for a dwell period at the end of each step, the improvement wherein said circuit means includes an electronic valve connected to generate a first signal at the end of each step and a second signal at the end of each dwell period, a current path connected across the armature of said motor, and switch means in said current path to close said current path at the end of each step in response to said first signal to electrodynamically brake said motor to a stop at the end of each step and to open said current path at the end of each dwell period in response to said second signal, said circuit means deenergizing said motor in response to said first signal and energizing said motor in response to said second signal.

2. In a motor system as recited in claim 1 wherein said switch means comprises a second electronic valve and wherein said circuit means includes a third electronic valve to deenergize and energize said motor in response to said first and second signals.

3. In a motor system for driving an output intermittently having an electric motor for driving said output and circuit means for energizing said motor to drive said output in steps, stopping for a dwell period at the end of each step, the improvement wherein said circuit means includes a current path connected across the armature of said motor, means to generate a first signal at the end of each step and a second signal at the end of each dwell period, switch means in said current path to close said current path at the end of each step in response to said first signal to electrodynamically brake said motor to a stop at the end of each step and to open said current path at the end of each dwell period in response to said second signal, and dwell selection means to adjust the length of said dwell period over a continuous range from zero to a maximum, said means to generate said first and second signals being inoperative to generate said first signal at the end of each step when the length of said dwell period is adjusted to zero by said dwell selection means, said circuit means deenergizing said motor in response to said first signal and energizing said motor in response to said second signal.

4. In a motor system for driving an output intermittently having an electric motor for driving said output and circuit means for energizing said motor to drive said output in steps, stopping for a dwell period at the end of each step, the improvement wherein said ciRcuit means includes a current path connected across the armature of said motor, means to provide a first signal at the end of each step and a second signal at the end of each dwell period, means to differentiate said first and second signals, and switch means in said current path to close said current path at the end of each step in response to the differentiation of said first signal to electrodynamically brake said motor to a stop at the end of each step and to open said current path at the end of each dwell period in response to the differentiation of said second signal, said circuit means deenergizing said motor in response to said first signal and energizing said motor in response to said second signal.

5. In a motor system as recited in claim 4, wherein said means to differentiate said first and second signals comprises an RC circuit connected between said means to provide said first and second signals and said switch means.

6. In an intermittent windshield wiper system as recited in claim 8 wherein said control means opens said switch means at the end of each dwell period before said circuit means re-energizes said motor at the end of each dwell period.

7. In an intermittent windshield wiper system having an electric motor for driving windshield wipers through repeating wiping cycles and circuit means for energizing said motor to drive said wipers intermittently stopping for dwell periods at the ends of successive wiping cycles, the improvement wherein said circuit means includes means to electrodynamically brake said motor to a stop at the ends of such successive wiping cycles including an electronic valve connected in a current path shunting the armature of said motor, control means switching said electronic valve between conductive and nonconductive states in a manner so that said electronic valve is conductive at the ends of such successive wiping cycles and is nonconductive at the end of each dwell period, and dwell selection means to adjust the length of said dwell periods over a continuous range from zero to a maximum, said control means maintaining said valve in a nonconductive state when the length of said dwell periods is adjusted to zero by said dwell selection means.

8. In an intermittent windshield wiper system having an electric motor for driving windshield wipers through repeating wiping cycles and circuit means for energizing said motor to drive said wipers intermittently, stopping for dwell periods at the ends of successive wiping cycles, the improvement wherein said circuit means includes a current path connected across the armature of said motor and switch means in said current path for opening and closing said current path, control means for closing said switch means at the ends of such successive wiping cycles to electrodynamically brake said motor to a stop at the ends of such successive wiping cycles and to open said switch means at the end of each dwell period.

9. In an intermittent windshield wiper system as recited in claim 8 wherein said control means includes means to provide a first signal at the ends of such successive wiping cycles and a second signal at the end of each dwell period, wherein said switch means closes said current path in response to said first signal and opens said current path in response to said second signal, and wherein said circuit means deenergizes said motor in response to said first signal and energizes said motor in response to said second signal.

10. In an intermittent windshield wiper system as recited in claim 9 wherein said means to generate said first and second signals comprises an electronic valve.

11. In an intermittent windshield wiper system as recited in claim 10 wherein said switch means comprises a second electronic valve and wherein said circuit means includes a third electronic valve to deenergize and energize said motor in response to said first and second signals.

12. In an intermittent windshield wiper system as recited in claim 9 wherein said circuit means includes dwEll selection means to adjust the length of said dwell period over continuous range from zero to a maximum and wherein said means to generate said first and second signals is inoperative to generate said first signal at the end of each wiping cycle when the length of said dwell period is adjusted to zero by said dwell selection means.

13. An intermittent windshield wiper system as recited in claim 9 wherein said control means includes means to differentiate said first and second signals and wherein said switch means closes and opens said current path in response to the differentiation of said first and second signals.

14. An intermittent windshield wiper system as recited in claim 13 wherein said means to differentiate said first and second signals comprises an RC circuit connected between said means to provide said first and second signals and said switch means.

15. In an intermittent windshield wiper system as recited in claim 8 wherein said switch means comprises an electronic valve.

16. In an intermittent windshield wiper system having an electric motor for driving windshield wipers through repeating cycles and means for energizing said motor to drive said wipers intermittently, stopping for dwell periods at the ends of successive wiping cycles, the improvement wherein said circuit means includes dwell selection means to adjust the length of said dwell periods over a continuous range from zero to a maximum, brake means to brake said motor when actuated, and control means to actuate said brake means to brake said motor to a stop at the ends of such successive wiping cycles except when said dwell period is adjusted to zero by said dwell selection means, said control means maintaining said brake means deactuated and inoperative to brake said motor when said dwell period is adjusted to zero by said dwell selection means.

17. In an intermittent windshield wiper system as recited in claim 16 wherein said brake means comprises means to electrodynamically brake said motor.

18. In an intermittent windshield wiper system having an electric motor for driving windshield wipers through repeating wiping cycles and circuit means for energizing said motor to drive said wipers intermittently stopping for dwell periods at the ends of successive wiping cycles, the improvement wherein said circuit means includes means to brake said motor when actuated, control means to actuate said braking means to brake said motor to a stop at the ends of such successive wiping cycles and to deactuate said braking means to disable said braking means from opposing rotation of said motor at the end of each dwell period.