Caster wheel with constant force mechanism

• US 10,315,900 B2
• Filed: 04/01/2014
• Issued: 06/11/2019
• Est. Priority Date: 04/01/2014
• Status: Active Grant

• Current Assignee: The Raymond Corporation (Toyota Motor Corporation)
• Original Assignee: The Raymond Corporation (Toyota Motor Corporation)
• Inventors: Goncalves, Fernando D., Finnegan, Paul F., Sigman, Greg, Brown, Michael V.
• Primary Examiner(s): Hail, Joseph J
• Assistant Examiner(s): Milanian, Arman
• Application Number:
  US14/242,491
• Publication Number:
  US 20150274495A1
• Time in Patent Office: 1,897 Days
• Field of Search: 16 44, 180411, 254 2 R
• CPC Class Codes: B60B 33/045 mounted resiliently, by means of dampers
• CPC Class Codes: B60G 11/16 characterised by means specially adapted for attaching the spring to axle or sprung part of the vehicle
• CPC Class Codes: B60G 2204/124 Mounting of coil springs
• CPC Class Codes: B60G 2300/022 Fork lift trucks, Clark
• CPC Class Codes: B60G 3/02 with a single pivoted arm
• CPC Class Codes: B62B 2301/23 the pressure of the wheel on the ground being controlled, e.g. by the load or the wheel slip
• CPC Class Codes: B62B 3/0612 power operated
• CPC Class Codes: B62B 5/00 Accessories or details specially adapted for hand carts B62B3/1404 , B62B9/00 take precedence; wheels, axles, or axle bearings for vehicles B60B; castors for vehicles, castors in general B60B33/00
• CPC Class Codes: B66F 9/065 non-masted mobile jacks of the garage type mounted on wheels or rollers B66F5/00
• CPC Class Codes: B66F 9/07586 Suspension or mounting of wheels on chassis
• CPC Class Codes: G08B 21/18 Status alarms G08B21/02 takes precedence

Abstract

A wheel assembly includes a constant force mechanism and a wheel coupled to the constant force mechanism. The wheel is displaceable in at least one dimension, and the constant force mechanism imparts a substantially constant force on the wheel in the dimension. In one aspect, the wheel is displaceable in a first regime and a second regime. For a wheel displacement in the first regime, the constant force mechanism imparts a substantially constant force on the wheel, and for a wheel displacement in the second regime, the constant force mechanism imparts a variable force on the wheel. The variable force can be linear or non-linear to the magnitude of the displacement in the second regime and is equal to or greater than the substantially constant force.

Claims

1. A wheel assembly comprising:

a constant force mechanism;

a wheel coupled to the constant force mechanism, the wheel being displaceable in at least one dimension;

a first position sensor that can detect at least one of a vertical displacement and a horizontal displacement of the wheel on the wheel assembly;

a second position sensor that can detect the other of the at least one of the vertical displacement and the horizontal displacement of the wheel; and

the constant force mechanism imparts a substantially constant force on the wheel in the at least one dimension,

wherein for a wheel displacement greater than a predetermined wheel displacement, the constant force mechanism imparts a variable force on the wheel, and

wherein the variable force is equal to or greater than the substantially constant force.

2. The wheel assembly of claim 1, wherein the first position sensor measures a deflection of the wheel, the first position sensor being in communication with a sensor system, and the sensor system generates a signal when the measured deflection of the wheel exceeds a predetermined threshold.

3. The wheel assembly of claim 2, wherein the signal communicates the deflection of the wheel.

4. The wheel assembly of claim 2, wherein the sensor system is configured to determine an average deflection across the wheel.

5. The wheel assembly of claim 2, wherein the signal indicates that the wheel could require maintenance.

6. The wheel assembly of claim 1, wherein the constant force mechanism is coupled to a vehicle.

7. The wheel assembly of claim 6, wherein the vehicle is a material handling vehicle.

8. The wheel assembly of claim 1, wherein the constant force mechanism includes:

a first support structure and a second support structure, the first support structure being arranged at a substantially right angle to the second support structure;

a first carriage movable along a length of the first support structure;

a second carriage movable along a length of the second support structure;

a rigid arm pivotally connected to the first and second carriages;

a first resistance device opposing movement of the first carriage along the length of the first support structure; and

a second resistance device opposing movement of the second carriage along the length of the second support structure.

9. The wheel assembly of claim 8, where the constant force mechanism is a variable constant force mechanism.

10. The wheel assembly of claim 8, further including a third resistance device opposing movement of one of the first and second carriages;

and

in a first regime, the constant force mechanism imparts the substantially constant force on the wheel for a translational displacement less than a distance X along one of the length of the first support structure and the length of the second support structure, and in a second regime, the constant force mechanism imparts the variable force on the wheel for a translational displacement equal to or greater than the distance X along one of the length of the first support structure and the length of the second support structure.

11. The wheel assembly of claim 1, wherein the wheel is at least one of a load wheel, a drive wheel, a caster wheel, and a steering wheel.

20. The wheel assembly of claim 2, wherein the signal indicates a wear on a second wheel.

21. The wheel assembly of claim 20, wherein the constant force mechanism is coupled to a vehicle;

and wherein the second wheel is at least one of a load wheel, a drive wheel, a caster wheel, and a steering wheel.

22. The wheel assembly of claim 1, wherein the first position sensor is a linear position sensor.

12. A method of indicating a maintenance requirement, the method comprising:

providing a vertical position sensor configured to measure a vertical deflection of a wheel on a wheel assembly on a material handling vehicle;

providing a horizontal position sensor configured to measure a horizontal deflection of the wheel on the wheel assembly;

measuring the deflection of the wheel; and

communicating a signal representing the deflection of the wheel, wherein the signal provides an indication for maintenance of the wheel assembly,

wherein the wheel assembly includes a constant force mechanism and the wheel coupled to the constant force mechanism, the wheel being displaceable in a first regime,

wherein for a wheel displacement in the first regime, the method further includes imparting a substantially constant force on the wheel, and

wherein the signal is communicated when the deflection of the wheel exceeds a predetermined threshold.

13. The method of claim 12, further including a second regime, and for a wheel displacement in the second wheel regime, the method further includes imparting a variable force on the wheel, the variable force being proportional to the magnitude of the displacement in the second regime equal to or greater than the substantially constant force, and the signal is communicated when the wheel displacement is in the second regime.

14. The method of claim 12, wherein the vertical position sensor is a linear encoder for measuring the deflection across the wheel.

15. The method of claim 14, wherein the step of communicating a signal representing the deflection of the wheel assembly occurs when the deflection across the wheel exceeds a predetermined threshold.

16. A material handling vehicle comprising:

a vehicle chassis;

a fork carriage coupled to the vehicle chassis;

at least one lifting fork coupled to the fork carriage and displaceable in at least one dimension;

a drive wheel coupled to the vehicle chassis;

at least one caster wheel assembly coupled to the vehicle chassis, the at least one caster wheel assembly including a constant force mechanism, a first position sensor, a second position sensor, and a caster wheel, the caster wheel coupled to the constant force mechanism, the first position sensor positioned to measure a vertical deflection across the caster wheel, and the second position sensor positioned to measure a horizontal deflection across the caster wheel; and

the constant force mechanism exerts a substantially constant force on the caster wheel resisting displacement of the caster wheel in a first regime, and exerts a variable force on the caster wheel in a second regime.

17. The material handling vehicle of claim 16, wherein the caster wheel assembly includes a second position sensor to measure a horizontal deflection of the caster wheel.

18. The material handling vehicle of claim 17, wherein the first position sensor measures a vertical deflection of the caster wheel, the first position sensor being in communication with a sensor system, and the sensor system generates a signal when a measured vertical deflection of the caster wheel exceeds a predetermined threshold.

19. The material handling vehicle of claim 18, wherein the signal indicates that the caster wheel requires maintenance.

23. The material handling vehicle of claim 16, wherein the first position sensor is a linear position sensor.