Front steering module for a zero turn radius vehicle

• US 10,035,537 B2
• Filed: 02/09/2015
• Issued: 07/31/2018
• Est. Priority Date: 07/07/2006
• Status: Active Grant

• Current Assignee: Hydro-Gear Limited Partnership
• Original Assignee: Hydro-Gear Limited Partnership
• Inventors: Hauser, Raymond, Bennett, Michael L., Bell, Douglas W.
• Primary Examiner(s): Rocca, Joseph M
• Assistant Examiner(s): Yeagley, Daniel S
• Application Number:
  US14/617,476
• Publication Number:
  US 20150151781A1
• Time in Patent Office: 1,268 Days
• CPC Class Codes: B62D 11/003 Electric or electronic control systems
• CPC Class Codes: B62D 11/04 by means of separate power sources
• CPC Class Codes: B62D 3/02 mechanical
• CPC Class Codes: B62D 5/0418 Electric motor acting on road wheel carriers
• CPC Class Codes: B62D 5/046 Controlling the motor
• CPC Class Codes: B62D 6/008 Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications
• CPC Class Codes: B62D 7/12 with twin-output steering gear

Abstract

A front steering module adapted for integration with the subframe of a zero-turn radius vehicle incorporating an electronic steering apparatus. The module provides both front wheel steering and corresponding control inputs for the electronic steering apparatus. The module has a frame member having a pair of steered wheel assemblies mounted thereto and a mounting member for attachment to the vehicle. The module further comprises a steering mechanism and a steering position sensor for providing input to the electronic steering apparatus.

Claims

1. A modular front steering assembly adapted to integrate with a vehicle having a prime mover, a subframe, an accelerator, a power source, and a pair of variable drive units, each variable drive unit driving one of a pair of axles, the modular front steering assembly comprising:

a frame member, non-integral with the vehicle subframe, having opposed ends and adapted for attachment to the vehicle subframe;

a first wheel assembly attached to a first end of the frame member and pivotable about a first vertical steering axis and a second wheel assembly attached to a second end of the frame member and pivotable about a second vertical steering axis;

a steering mechanism operatively connected to the first and second wheel assemblies and comprising a steering column, a steering input device connected to the steering column, and a steer-by-wire assemblage operatively connecting the steering input device and the first and second wheel assemblies; and

an electronic drive control system adapted to independently adjust the speed and rotational direction of the output from each variable drive unit including;

a pair of electric actuators, each adapted for attachment to one of the variable drive units and to adjust the output thereof;

a pair of actuator position sensors, each in communication with one of the electric actuators;

a steering position sensor adapted for sensing a position of the steering input device;

an accelerator position sensor adapted for sensing a position of the accelerator;

a first speed sensor adapted for sensing the speed of one of the axles and a second speed sensor adapted for sensing the speed of the other of the axles; and

a controller in communication with the accelerator position sensor, the steering position sensor, the first speed sensor, the second speed sensor, the pair of actuator position sensors, the pair of electric actuators, the prime mover, and the power source;

wherein the controller generates and transmits first control signals to the pair of electric actuators to independently control the speed of the output from each variable drive unit, the first control signals based on signals received by the controller from each of the accelerator position sensor, the steering position sensor, the first speed sensor, the second speed sensor, and the pair of actuator position sensors; and

wherein the controller generates and transmits second control signals to the steer-by-wire assemblage to independently control the rotational position of each of the first and second wheel assemblies about the first and second vertical steering axes, the second control signals based on the signals received by the controller from each of the accelerator position sensor, the steering position sensor, the first speed sensor, the second speed sensor, and the pair of actuator position sensors.

2. The modular front steering assembly of claim 1, wherein the steer-by-wire assemblage comprises:

first and second reduction gear assemblies in respective mechanical communication with the first and second wheel assemblies; and

first and second electric motors respectively driving the first and second reduction gear assemblies and capable of being communicatively connected with the electronic drive control system of the vehicle.

3. The modular front steering assembly of claim 2, wherein each of the first and second electric motors is configured to respectively drive the first and second reduction gear assemblies to respectively rotate each of the first and second wheel assemblies about the first and second vertical steering axes.

4. The modular front steering assembly of claim 2, further comprising a wiring harness connected to the first and second electric motors and to the steering position sensor.

5. The modular front steering assembly of claim 1, wherein the steering mechanism induces a progressive Ackerman effect in the first and second wheel assemblies sufficient to rotate the first and second wheel assemblies on a common arc about a center of rotation of the vehicle.

6. The modular front steering assembly of claim 1, wherein each of the pair of electric actuators comprises a rotary actuator.

7. The modular front steering assembly of claim 1, further comprising a steering column support connecting the frame member and the steering column.

8. The modular front steering assembly of claim 1, wherein the steering input device comprises a steering wheel attached to the steering column.

9. The modular front steering assembly of claim 1, wherein the independent control of the speed of the output from each variable drive facilitates both straight line operation and turning of the vehicle, in cooperation with the independent control of the rotational positions of the first and second wheel assemblies.

10. A front steering assembly for use with a vehicle having a vehicle subframe and an electronic drive control system, the front steering assembly comprising:

a frame member, non-integral with the vehicle subframe, and having opposed ends;

a mounting member located on the frame member, wherein the mounting member is adapted for attachment to the vehicle subframe;

a first wheel assembly attached to a first end of the frame member and pivotable about a first vertical steering axis and a second wheel assembly attached to a second end of the frame member and pivotable about a second vertical steering axis;

a steering mechanism operatively connected to the first and second wheel assemblies, the steering mechanism comprising a steering column, a steering input device connected to the steering column, and a steer-by-wire assemblage operatively connecting the steering input device and the first and second wheel assemblies, wherein the steering mechanism induces a progressive Ackerman effect in the first and second wheel assemblies as the steering input device is moved away from a center position; and

a steering position sensor mounted to the steering mechanism for sensing movement of the steering mechanism and capable of being communicatively connected with the electronic drive control system of the vehicle, wherein the steering position sensor emits a signal proportional to the movement of the steering mechanism;

wherein the front steering assembly as a whole is modular and adapted for attachment to the vehicle subframe and the electronic drive control system such that the vehicle is capable of zero-radius turn operation or near zero-radius turn operation.

11. The front steering assembly of claim 10, wherein the steer-by-wire assemblage comprises:

first and second reduction gear assemblies in respective mechanical communication with the first and second wheel assemblies; and

first and second electric motors respectively driving the first and second reduction gear assemblies and capable of being communicatively connected with the electronic drive control system of the vehicle.

12. The front steering assembly of claim 11, wherein each of the first and second electric motors is configured to respectively drive the first and second reduction gear assemblies to respectively rotate each of the first and second wheel assemblies about the first and second vertical steering axes.

13. The front steering assembly of claim 11, further comprising a wiring harness connected to the first and second electric motors and to the steering position sensor.

14. The front steering assembly of claim 10, wherein the steering mechanism induces a progressive Ackerman effect in the first and second wheel assemblies sufficient to rotate the first and second wheel assemblies on a common arc about a center of rotation of the vehicle.

15. The front steering assembly of claim 10, wherein the steering input device comprises a steering wheel attached to the steering column.

16. A modular front steering assembly adapted to integrate with a vehicle having a prime mover, a subframe, an accelerator, a power source, and a pair of variable drive units, each variable drive unit driving one of a pair of axles, the modular front steering assembly comprising:

a frame member, non-integral with the vehicle subframe, having opposed ends and adapted for attachment to the vehicle subframe;

a first wheel assembly attached to a first end of the frame member and pivotable about a first vertical steering axis and a second wheel assembly attached to a second end of the frame member and pivotable about a second vertical steering axis;

a steering mechanism operatively connected to the first and second wheel assemblies and comprising a steering column, a steering input device connected to the steering column, and a steer-by-wire assemblage operatively connecting the steering input device and the first and second wheel assemblies; and

an electronic drive control system adapted to independently adjust the speed and rotational direction of the output from each variable drive unit including;

a pair of electric actuators, each adapted for attachment to one of the variable drive units and to adjust the output thereof;

a steering position sensor adapted for sensing a position of the steering input device;

an accelerator position sensor adapted for sensing a position of the accelerator;

a first speed sensor adapted for sensing the speed of one of the axles and a second speed sensor adapted for sensing the speed of the other of the axles; and

a controller in communication with the accelerator position sensor, the steering position sensor, the first speed sensor, the second speed sensor, the pair of electric actuators, the prime mover, and the power source;

wherein the controller generates and transmits first control signals to the pair of electric actuators to independently control the speed of the output from each variable drive unit, the first

control signals based on signals received by the controller from each of the accelerator position sensor, the steering position sensor, the first speed sensor, and the second speed sensor.

17. The modular front steering assembly of claim 16, wherein the controller generates and transmits second control signals to the steer-by-wire assemblage to independently control the rotational position of each of the first and second wheel assemblies about the first and second vertical steering axes, the second control signals based on the signals received by the controller from each of the accelerator position sensor, the steering position sensor, the first speed sensor, and the second speed sensor.

18. The modular front steering assembly of claim 16, wherein each of the pair of electric actuators comprises a linear actuator.