Hill Hold For An Electric Vehicle

• US 20090107740A1
• Filed: 10/29/2007
• Published: 04/30/2009
• Est. Priority Date: 10/29/2007
• Status: Active Grant

• Current Assignee: Textron Innovations Incorporated (Textron Inc)
• Original Assignee: Textron Inc
• Inventors: Bell, Oliver A., Clark, Warren
• Granted Patent: US 7,926,889 B2
• Time in Patent Office: Days
• US Class Current: 180/65.100
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 15/2018 for braking on a slope
• CPC Class Codes: B60L 15/2027 whilst maintaining constant speed
• CPC Class Codes: B60L 15/2081 for drive off on a slope
• CPC Class Codes: B60L 2200/22 Microcars, e.g. golf cars
• CPC Class Codes: B60L 2210/20 AC to AC converters
• CPC Class Codes: B60L 2220/18 Reluctance machines
• CPC Class Codes: B60L 2240/30 Parking brake position
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/425 Temperature
• CPC Class Codes: B60L 2240/427 Voltage
• CPC Class Codes: B60L 2240/429 Current
• CPC Class Codes: B60L 2240/80 Time limits
• CPC Class Codes: B60L 2250/28 Accelerator pedal thresholds
• CPC Class Codes: B60L 2260/22 Standstill, e.g. zero speed
• CPC Class Codes: B60L 3/0061 relating to electrical machines
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 50/52 characterised by DC-motors
• CPC Class Codes: B60L 50/60 using power supplied by batteries in combination with fuel cells B60L50/75
• CPC Class Codes: B60L 7/26 : Controlling the braking effect
• CPC Class Codes: B60T 2270/89 : Criteria for brake release
• CPC Class Codes: B60T 7/122 : for locking of reverse movement
• CPC Class Codes: B60T 8/245 : Longitudinal vehicle inclination
• 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
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility

Abstract

A method for braking an electric utility vehicle including a motor and an electromechanical brake. The method includes storing a value indicative of at least one of an amount of current, voltage, and power that is commanded to a motor of the electric utility vehicle to maintain the electric utility vehicle in a stopped state; engaging a parking brake function of an electromechanical brake after the storing; disabling the motor after the engaging; commanding the at least one of the current, voltage, and power to the motor at the stored value when an accelerator pedal is depressed; and disengaging the parking brake function after the commanding.

Claims

1. A method for braking an electric utility vehicle including a motor and an electromechanical brake, comprising:

storing a value indicative of at least one of an amount of current, voltage, and power that is commanded to a motor of the electric utility vehicle to maintain the electric utility vehicle in a stopped state;

engaging a parking brake function of an electromechanical brake after the storing;

disabling the motor after the engaging;

commanding the at least one of the current, voltage, and power to the motor at the stored value when an accelerator pedal is depressed; and

disengaging the parking brake function after the commanding.

2. The method of claim 1, further comprising determining when the electric utility vehicle is stopped on an incline and performing the storing, engaging, disabling, commanding, and disengaging when the electric utility vehicle is determined to be stopped on an incline.

3. The method of claim 2, the determining comprises monitoring at least one of a speed of the electric utility vehicle and a holding torque to determine the stopped state of the electrical vehicle.

4. The method of claim 1, further comprising determining when a parking brake function is desired based on a speed of the electric utility vehicle and the storing, engaging, disabling, commanding, and disengaging is performed when a parking brake function is desired.

5. The method of claim 1, the storing the value comprises storing the value indicative of the at least one of the amount of the current, voltage, and power after the electric utility vehicle is stopped for a predetermined time period.

6. The method of claim 5, the predetermined time period being in the range of 0.8 to 2.2 seconds.

7. A system for controlling dynamic braking of an electric utility vehicle, comprising:

a brake pedal position sensor that generates a brake position signal corresponding to a position of a brake pedal;

an accelerator position sensor that generates an accelerator signal corresponding to a position of an accelerator pedal; and

a controller that receives the brake position signal and the accelerator signal and transmits a motor control signal to a motor based on the brake position signal and the accelerator pedal signal, and the controller stores a value indicative of an amount of at least one of current, voltage, and power to maintain electric utility vehicle 10 in a stopped state on the hill after the park brake function is disabled or disengaged when the electric utility vehicle achieves a first predetermined speed, and the controller generates the motor control signal in accordance with the stored value when the accelerator signal indicates a command to increase the speed of the electric utility vehicle above a second predetermined speed.

8. The system of claim 7, the first predetermined speed is approximately zero.

9. The system of claim 8, the controller configured to store the value based on at least one of a vehicle speed and a torque required to maintain the vehicle at the vehicle speed.

10. The system of claim 7, the controller configured to store the value indicative of the at least one of the current, voltage, and power when the electric utility vehicle achieves the first speed for a predetermined time period.

11. The system of claim 10, the predetermined time period being in the range of 0.8 to 2.2 seconds.

12. The system of claim 10, the controller configured to command a parking brake function of an electromechanical brake on and commanding the motor off after storing the value.

13. The system of claim 12, the controller configured to command the parking brake function off after the accelerator signal indicates the command to increase the speed of the electric utility vehicle above the second predetermined speed.

14. An electric utility vehicle, comprising:

an electromechanical brake that functions as a parking brake based on a speed of the electric utility vehicle;

a motor that drives the electric utility vehicle; and

a controller that controls the motor and the electromechanical brake, that stores a value indicative of an amount of a current provided to the motor before engaging the parking brake function of the electromechanical brake, and that supplies current to the motor at the stored value before the electromechanical brake is disengaged.

15. The vehicle of claim 14, the controller configured to command the parking brake function of the electromechanical brake to engage after the electric utility vehicle comes to a stop on a hill.

16. The vehicle of claim 15, the controller configured to determine if the electric utility vehicle is stopped on a hill based on a vehicle speed and a torque necessary to maintain a predetermined vehicle speed.

17. The vehicle of claim 14, the controller configured to command the parking brake function of the electromechanical brake to engage after the electric utility vehicle reaches a predetermined speed and remains at or below the predetermined speed for a predetermined time period.

18. The vehicle of claim 17, the predetermined time period being in the range of 0.8 to 2.2 seconds.

19. The vehicle of claim 15, the controller configured to command the parking brake function of the electromechanical brake to disengage after receiving a signal indicating that an accelerator pedal is depressed and current has been restored to the motor.