Multi-speed drive with forward/reverse lockout

• US 4,378,855 A
• Filed: 08/20/1979
• Issued: 04/05/1983
• Est. Priority Date: 08/20/1979
• Status: Expired due to Term

• Current Assignee: Tennant Company
• Original Assignee: Tennant Company
• Inventors: Haub, Donald J., Krier, Keith N., Seim, Howard N., Brown, Neil T., Hawkins, Raymond C.
• Primary Examiner(s): Mitchell, David M.
• Application Number:
  US06/068,160
• Time in Patent Office: 1,324 Days
• Field of Search: 180/65 R, 180/65 F, 180/272, 180/271, 318/263, 318/273, 318/283, 318/284, 15/314, 15/389
• US Class Current: 180/65.1
• CPC Class Codes: B60L 3/02 Dead-man's devices
• CPC Class Codes: B60L 50/52 characterised by DC-motors
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

An improvement for electrically driven floor maintenance apparatus including means for varying the speed of the driving motors is disclosed. Two speed ranges are provided by switching means which change the interconnection of the drive motors from series for the low speed range, and parallel for the high speed range. Within each speed range, intermediate speeds are provided by placing resistors with shunt in series with the motors. Time delay circuitry is also included to prevent immediate operation of the vehicle in the high speed of each range until the vehicle has had some time to accelerate. Additionally, means are provided for detecting whether a vehicle is rolling in a forward or reverse direction and circuits are provided to prevent the operator from driving the vehicle in an opposite direction until the vehicle has slowed down to a near stop. A deadman control is provided to prevent the energizing of the drive motors when the operator is no longer seated on the driver'"'"'s seat. ///

Claims

1. A floor maintenance vehicle comprising in combination a body, a plurality of wheels for supporting said body, means for steering said vehicle, means for maintaining floor surfaces, a plurality of reversible electric drive motors, each of said motors having a field coil and an armature coil, said motors being adapted for driving said wheels, a power source, means for selectively changing the electrical connection between said plurality of motors from series to parallel and parallel to series, reversing means for reversing the flow of current through each of said field coils while leaving unchanged the flow of current through the corresponding armatures to reverse the direction of said motors, means for preventing reversing direction of said drive motors until said vehicle has slowed to a predetermined speed;

said preventing means including a circuit for sensing the rotation of said motors in a coasting state wherein said motors are rotating without voltage applied to said field coil and for preventing the application of voltage to said field coils which would reverse the direction of said motors until said motors have slowed to a predetermined rotational velocity, said circuit including;

voltage detecting means powered by said power source, said detecting means including means for amplifying a detected voltage, said detecting means being connected in parallel with said armature coils and having one pole of said armature coils and one side of said detecting means at the same electrical potential at all times for detecting voltage generated therein when said motor is in said coasting state and amplifying said voltage, and preventing means responsive to said detecting means for preventing application of said reversing voltage to said motor while said detecting means is sensing said generated voltage.

2. The apparatus of claim 1 wherein said motors comprise a first and second motor, said changing means includes first, second and third electric relay contacts where said first relay contact is of a normally closed type and where said second and third relay contacts are of a normally open type, and one side of said first motor being connected to the one side of said power source and one side of said second motor being connected to the other side of said power source, the other side of said first motor being connected to one side of said first relay contact and one side of said second relay contact, the other side of said second relay contact being connected to the other side of said power source, the other side of said second motor being connected to the other side of said first relay contact and one side of said third relay contact and the other side of said third relay contact is connected to said one side of said power source.

3. A floor maintenance vehicle comprising, in combination, a body, a plurality of wheels for supporting said body, means for steering said vehicle, means for maintaining floor surfaces, a plurality of reversible electric drive motors for driving said wheels, said motors each having an armature and a field coil, a power source for supplying current to said motors, means for controlling the current applied to said motors providing increasing and decreasing stepwise increments, means for switching said controlling means from one current increment to the next;

said controlling means including means for providing resistance and means for shunting said resistance means, said resistance means being in series with said motors and means for selectively changing the electrical connection of said motors with each other from series to parallel and from parallel to series, means for delaying application of said current increment until said vehicle has attained acceleration in forward velocity, and means for preventing reversing direction of said motors until said vehicle has slowed to a predetermined speed, circuit means for reversing the flow of current through said field coils to reverse the direction of the motors, and a circuit for sensing the rotation of at least one of said motors in a coasting state wherein said at least one motor is rotating without voltage applied to said field coil and means for preventing the application of voltage to said field coils which would reverse the direction of said motors until said at least one motor has slowed to a predetermined rotational velocity, said circuit including;

detecting means connected in parallel with the armature coil of said at least one motor with one side of said armature coil and one pole of said detecting means being at ground potential for detecting voltage generated therein when said at least one motor is in said coasting state, and preventing means responsive to said detecting means for preventing application of said reversing voltage to said motors while said detecting means is sensing said generated voltage.

4. The apparatus of claim 3 wherein said shunting means includes relay contacts placed across said resistance means and wherein said changing means includes further relay contacts.

5. The apparatus of claim 3 wherein said shunting means includes relay contacts placed across said resistance means and wherein said changing means includes a first, second and third electric relay contacts where said first relay contact is of a normally closed type and where said second and third relay contacts are of a normally open type, and one side of said first motor being connected to the one side of said power source and one side of said second motor being connected to the other side of said power source, the other side of said first motor being connected to one side of said first relay contact and one side of said second relay contact, the other side of said second relay contact being connected to the other side of said power source, the other side of said second motor being connected to the other side of said first relay contact and one side of said third relay contact and the other side of said third relay contact is connected to said one side of said power source.

6. A floor maintenance vehicle comprising, in combination, a body, a plurality of wheels for supporting said body, means for steering said vehicle, means for maintaining floor surfaces, a plurality of electric drive motors for driving said wheels, said motors having field and armature coils with one side of said armature coils at ground potential, a power source for supplying current to said motors, means for controlling the current applied to said motors, said controlling means being adapted to provide stepwise increasing and decreasing increments, means for switching said controlling means from one current increment to the next, means for delaying application of said next current increment until said vehicle has had some time to accelerate, means for selectively changing the electrical connection between said motors from series to parallel and from parallel to series, means for reversing the flow of current through said field coils for reversing the rotation of said motors;

and a control circuit for sensing rotation of at least one of said motors, said control circuit serving to prevent application of electrical power to said motors until said at least one motor has slowed to a predetermined rotational velocity, said control circuit including a transistor having a base and an emitter, said base being connected to the ungrounded side of said armature coil and said emitter being at ground potential.

7. An electrically driven riding vehicle comprising a vehicle body being supported on a plurality of wheels, an electrically reversible DC motor having field and armature coils, at least one of said wheels being driven by said motor, means for reversing the flow of current through said field coil to reverse the direction of the motor, and a control circuit for sensing the rotation of said motor in a coasting state wherein said motor is rotating without voltage applied to said coils and for preventing the application of voltage to said field coil which would reverse the direction of said motor until said motor has slowed to a predetermined rotational velocity, said control circuit including detecting means connected in parallel with said armature coil for detecting voltage generated therein when said motor is in said coasting state, and preventing means responsive to said detecting means for preventing application of said reversing voltage to said motor while said detecting means is sensing said generated voltage.

8. A riding type floor maintenance vehicle comprising a vehicle body including an electric motor, said body being supported on a plurality of wheels, at least one of said wheels being drivenly connected to said electric motor, said motor being electrically reversible, said vehicle including a control circuit for sensing rotation of said driven wheels and means for preventing the application of electrical power to said motor to reverse said motor until said wheels have slowed to a predetermined rotational velocity, said control circuit including a first control circuit for applying current to said motor causing said armature to rotate in a first direction;

and a second control circuit for applying current to said motor causing said armature to rotate in a second direction being opposite to said first direction;

said preventing means comprising a first normally closed relay contact in series with said first circuit, and second normally closed relay contact in series with said second circuit;

a first holding circuit means controlling said first relay contact, a second holding circuit means controlling said second relay contact;

means for detecting said generated voltage;

preventing means being responsive to said detecting means for preventing completion of said first circuit when said armature is rotating in said second direction and for preventing completion of said circuit when said armature is rotating in said first direction;

said first holding circuit means being responsive to said detecting means for holding said first relay contact in its open-circuit state until said armature has slowed to said predetermined speed when said armature is coating in said first direction;

said second holding circuit means being responsive to said detecting means for holding said second relay contact in its open-circuit state until said armature has slowed to said predetermined speed when said armature is coasting in said second direction; and

wherein said second holding circuit means includes a first relay coil for controlling said second relay contact;

a third relay contact responsive to said first relay coil and being in series with said first relay coil;

a fourth relay contact in parallel with said third relay contact;

a second relay coil in series with said first control circuit for controlling said fourth relay contact; and

wherein said first holding circuit means includes a third relay coil for controlling said first relay contact;

a fifth relay contact responsive to said third relay coil in series with said third relay coil;

a sixth relay contact in parallel with said first relay contact; and

a fourth relay coil in series with said second control circuit for controlling said sixth relay contact.

9. An electrically driven riding vehicle comprising a vehicle body including an electric motor, said body being supported on a plurality of wheels, at least one of said wheels being drivenly connected to said electric motor, said motor being electrically reversible, said vehicle including a control circuit for sensing rotation of said driven wheels and means of preventing the application of electrical power to said motor to reverse said motor until said wheels have slowed to a predetermined rotational velocity, said control circuit including a first control circuit for applying voltage to said motor causing said armature to rotate in a first direction;

and a second control circuit for applying voltage to said motor causing said armature to rotate in a second direction, said second direction being opposite to said first direction;

means for detecting said generated voltage;

said preventing means comprising a first normally closed relay contact in series with said first circuit, and a second normally closed relay contact in series with said second circuit;

a first holding circuit means controlling said first relay contact, a second holding circuit means controlling said second relay contact;

said preventing means being responsive to said detecting means for preventing completion of said first circuit when said armature is rotating in said second direction and for preventing completion of said second circuit when said armature is rotating in said first direction;

said first holding circuit means being responsive to said detecting means for holding said first relay contact in its open-circuit state until said armature has slowed to said predetermined speed when said armature is coasting in said first direction;

said second holding circuit means being responsive to said detecting means for holding said second relay contact in its open-circuit state until said armature has slowed to said predetermined speed when said armature is coasting in said second direction; and

wherein said second holding circuit means includes a first relay coil for controlling said second relay contact;

a third relay contact responsive to said first relay coil and being in series with said first relay coil;

a fourth relay contact in parallel with said third relay contact;

a second relay coil in series with said first control circuit for controlling said fourth relay contact; and

wherein said first holding circuit means includes a third relay coil for controlling said first relay contact;

a fifth relay contact responsive to said third relay coil in series with said third relay coil;

a sixth relay contact in parallel with fifth relay contact; and

a fourth relay coil in series with said second control circuit for controlling said sixth relay contact.

10. An electrically driven riding vehicle comprising a vehicle body including an electrically reversible DC motor having field and armature coils, said body being supported on a plurality of wheels at least one of said wheels being driven by said motor, a control circuit including means for reversing the flow of current through said field coil to reverse the direction of the motor, and a control circuit for sensing the rotation of an electrically reversible motor in a coasting state wherein said motor is rotating without voltage applied to said coils and for preventing the application of voltage to said field coil, which would reverse the direction of said motor until said motor has slowed to a predetermined rotational velocity, said control circuit including;

(a) detecting means connected in parallel with said armature coil for detecting voltage generated therein when said motor is in said coasting state,

(b) preventing means responsive to said detecting means for preventing application of said reversing voltage to said motor while said detecting means is sensing said generated voltage.

11. The circuit of claim 10 wherein said motor is capable of sustaining residual magnetism when no current is flowing in said field coil so that a voltage will be induced in said armature coil when rotated.