Pitch alleviation system

• US 20040026880A1
• Filed: 08/09/2002
• Published: 02/12/2004
• Est. Priority Date: 08/09/2002
• Status: Active Grant

• Current Assignee: Blue Leaf IP Incorporated (CNH Industrial N.V.), CNH Industrial America LLC (CNH Industrial N.V.)
• Original Assignee: Case Corporation (CNH Industrial N.V.)
• Inventors: Bundy, John E.
• Granted Patent: US 6,749,035 B2
• Time in Patent Office: Days
• US Class Current: 280/6.159
• CPC Class Codes: A01B 63/1006 the hydraulic or pneumatic means structurally belonging to the tractor
• CPC Class Codes: A01B 63/11 for controlling weight transfer between implements and tractor wheels
• CPC Class Codes: B60G 17/005 Suspension locking arrangements for retractable wheels B62D61/12
• CPC Class Codes: B60G 17/0152 characterised by the action on a particular type of suspension unit B60G17/01941 takes precedence
• CPC Class Codes: B60G 17/0161 mainly during straight-line motion B60G17/0164 takes precedence
• CPC Class Codes: B60G 17/056 Regulating distributors or valves for hydropneumatic systemsB60G17/044 - B60G17/048, B60G17/0416 take precedence; Fluid interconnection systems to control vehicle inclination B60G21/06, B60G21/10; valves per se F16K
• CPC Class Codes: B60G 2300/082 Tractors
• CPC Class Codes: B60G 2300/083 Boom carrying vehicles, e.g. for crop spraying
• CPC Class Codes: B60G 2400/204 Vehicle speed
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2400/61 Load distribution
• CPC Class Codes: B60G 2400/821 Uneven, rough road sensing affecting vehicle body vibration
• CPC Class Codes: B60G 2400/91 Frequency
• CPC Class Codes: B60G 2401/26 Resistance type, e.g. as level indicator
• CPC Class Codes: B60G 2500/02 Supply or exhaust flow rates; Pump operation
• CPC Class Codes: B60G 2500/20 Spring action or springs
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2600/122 Summation signal
• CPC Class Codes: B60G 2600/182 Active control means
• CPC Class Codes: B60G 2800/014 Pitch; Nose dive
• CPC Class Codes: B60G 2800/214 : by varying the load distribution
• CPC Class Codes: B60G 2800/912 : Attitude Control; levelling control
• CPC Class Codes: B60G 2800/915 : Suspension load distribution
• CPC Class Codes: E02F 9/2207 : for reducing or compensating oscillations
• CPC Class Codes: E02F 9/2217 : with energy recovery arrangements, e.g. using accumulators, flywheels
• CPC Class Codes: E02F 9/2257 : Vehicle levelling or suspension systems suspensions for vehicles in general B60G
• CPC Class Codes: E02F 9/226 : Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating

Abstract

A hitch control system for a work vehicle combines a front suspension position signal, a hitch load signal and a hitch position signal to generate a valve command signal that controls hitch position so as to alleviate pitching and maximize front wheel ground contact time.

Claims

1. A tractor having a ride control system that alleviates tractor pitching, comprising:

a chassis;

an engine mounted on the chassis;

a hydraulic pump coupled to and driven by the engine to provide a flow of pressurized hydraulic fluid;

a front suspension including two front wheels disposed on opposing sides of the chassis and supported by at least one front suspension hydraulic actuator configured to raise and lower the two front wheels with respect to the chassis;

a front suspension sensor coupled to the front suspension to generate a signal indicative of the position of the front suspension with respect to the chassis;

two rear wheels coupled to the chassis to rotate with respect thereto and drive the vehicle over the ground;

a multi-point hitch coupled to the rear of the chassis and configured to be coupled to an overhanging load extending from the rear of the chassis;

a hitch position sensor coupled to the hitch to provide a signal indicative of an elevation of the hitch with respect to the chassis;

a hitch hydraulic actuator coupled to the hitch to raise and lower the hitch with respect to the chassis;

a load sensor coupled to the chassis to provide a signal indicative of a load on the hitch;

at least one electrically actuated hitch control valve coupled to and between the pump and the hitch hydraulic actuator to regulate the flow of pressurized hydraulic fluid to the hitch hydraulic actuator;

an electronic control circuit coupled to and responsive to the front suspension sensor, the load sensor, and the hitch position sensor, and the hitch proportional control valve to control the flow of pressurized hydraulic fluid to the hitch hydraulic actuator in real time to alleviate tractor pitching.

2. The tractor of claim 1, wherein the electronic control circuit includes at least one feedback control circuit configured to automatically, periodically, and repeatedly receive the signals of the front suspension sensor, the load sensor and the hitch position sensor, to combine the signals, to generate a valve control signal therefrom, and to apply the valve control signal to the hitch control valve to vary a degree of opening of the hitch control valve.

3. The tractor of claim 2, wherein the electronic control circuit is configured to sample the signals of the front suspension sensor, the load sensor and the hitch position sensor at least once every 50 milliseconds and to generate the valve control signal at least once every 50 milliseconds.

4. The tractor of claim 3, further comprising at least one front suspension hydraulic control valve coupled to and between the pump and the at least one front suspension hydraulic actuator to control the height of the front suspension, and further wherein the front suspension hydraulic control valve is coupled to and driven by the electronic control circuit.

5. The tractor of claim 4, wherein the electronic control circuit includes:

a first digital microprocessor coupled to the front suspension control valve and the front suspension sensor; and

a second digital microprocessor coupled to the hitch position sensor and the load sensor; and

a CAN bus coupling the first and second digital microprocessors and configured to transmit the signal indicative of the position of the front suspension with respect to the chassis from the first digital microprocessor to the second digital microprocessor.

6. The tractor of claim 5, wherein the second microprocessor is coupled to the hitch control valve and is configured to receive the signal indicative of the position of the front suspension over the CAN bus, to combine that signal with the hitch position sensor signal and the load sensor signal, to generate a valve control signal therefrom, and to apply the valve control signal to the hitch control valve to vary a degree of opening of the hitch control valve.

7. A method of electronically reducing pitching in a tractor, comprising the steps of:

(a) receiving an electrical signal from a front suspension sensor indicating the position of a front suspension;

(b) receiving an electrical signal from a hitch position sensor indicating the height of a hitch with respect to a chassis;

(c) receiving an electrical signal from a load sensor indicative of a load experienced by the hitch;

(d) combining the front suspension sensor signal, the hitch position sensor signal and the load sensor signal;

(e) generating a hitch hydraulic actuator signal calculated to drive the hitch upward or downward with respect to the chassis; and

(f) driving the hitch upward or downward with respect to the chassis to thereby reduce tractor pitching.

8. The method of claim 7, wherein steps (a)-(f) are automatically and repeatedly executed at least once every 50 milliseconds.

9. The method of claim 8, further including the step of transmitting the front suspension sensor signal from a first microprocessor that is coupled to the hitch position sensor to a second microprocessor, and further wherein the step of combining includes the step of combining the front suspension sensor signal, the hitch position sensor signal and the load sensor signal in the second microprocessor.

10. The method of claim 9, wherein the step of generating a hitch hydraulic actuator signal includes the step of generating the hydraulic actuator signal in the second microprocessor and applying the hydraulic actuator signal to a valve that is fluidly coupled to and between a hydraulic pump and a hitch hydraulic actuator to regulate a flow of hydraulic fluid from the pump to the actuator.

11. A work vehicle having a ride control system that alleviates vehicle pitching, comprising:

a chassis;

an engine mounted on the chassis;

a hydraulic pump coupled to and driven by the engine to provide a flow of pressurized hydraulic fluid;

a front suspension including two front wheels disposed on opposing sides of the chassis and supported by at least one front suspension hydraulic actuator configured to raise and lower the two front wheels with respect to the chassis;

a front suspension sensor coupled to the front suspension to generate a signal indicative of the position of the front suspension with respect to the chassis;

two rear wheels coupled to the chassis to rotate with respect thereto and drive the vehicle over the ground;

a hitch coupled to the rear of the chassis and configured to be coupled to an overhanging load extending from the chassis;

a hitch position sensor coupled to the hitch to provide a signal indicative of an elevation of the hitch with respect to the chassis;

a hitch hydraulic actuator coupled to the hitch to raise and lower the hitch with respect to the chassis;

a load sensor coupled to the chassis to provide a signal indicative of a load on the hitch;

at least one electrically actuated hitch control valve coupled to and between the pump and the hitch hydraulic actuator to regulate the flow of pressurized hydraulic fluid to the hitch hydraulic actuator;

an electronic control circuit coupled to and responsive to the front suspension sensor, the load sensor, the hitch position sensor, and the hitch control valve to control the flow of pressurized hydraulic fluid to the hitch hydraulic actuator in real time to alleviate vehicle pitching.

12. The work vehicle of claim 11, wherein the electronic control circuit includes at least one feedback control circuit configured to automatically, periodically, and repeatedly receive the signals of the front suspension sensor, the load sensor and the hitch position sensor, to combine the signals, to generate a valve control signal therefrom, and to apply the valve control signal to the hitch control valve to vary a degree of opening of the hitch control valve.

13. The work vehicle of claim 12, wherein the electronic control circuit is configured to sample the signals of the front suspension sensor, the load sensor and the hitch position sensor at least once every 50 milliseconds and to generate the valve control signal at least once every 50 milliseconds.

14. The work vehicle of claim 13, further comprising at least one front suspension hydraulic control valve coupled to and between the pump and the at least one front suspension hydraulic actuator to control the extension of the front suspension, and further wherein the front suspension hydraulic control valve is coupled to and driven by the electronic control circuit.

15. The work vehicle of claim 14, wherein the electronic control circuit includes:

a first digital microprocessor coupled to the front suspension control valve and the front suspension sensor; and

a second digital microprocessor coupled to the hitch position sensor and the load sensor; and

a CAN bus coupling the first and second digital microprocessors and configured to transmit the signal indicative of the position of the front suspension with respect to the chassis from the first digital microprocessor to the second digital microprocessor.

16. The work vehicle of claim 11, wherein the electronic control circuit is configured to sense a front suspension sensor signal indicative of the front wheels lifting off the ground and to operate the hitch responsively.

17. The work vehicle of claim 16, wherein the signal indicative of the wheels lifting off the ground is generated from the front suspension sensor signal using a dynamic model that predicts that the front wheels will leave the ground.