Caterpillar Inc.

Caterpillar Tractor Co.

Other

Weldon L Phelps

Alan L Stahl

Robert G Miller

John P Hoffman

Javad Hosseini

Randall M Mitchell

Larry Ellis Kendrick

Giles Kent Sorrells

Alfred W Sieving

James E Schimpf

Gregory L Williamson

Stephen J Morey

Eric A Hutchison

Allen D Myers

Val G Boucher

James P Mueller

Steven W Judy

Daniel R Ekstrand

April D Ohlson

An apparatus, for controllably driving a plurality of solenoids is provided. The apparatus includes a plurality of driver circuits. The plurality of driver circuits are configurable as one of proportional and binary driver circuits. A first number of the plurality of driver circuits include proportional driver circuits and a second number of the plurality of driver circuits include binary driver circuits. The apparatus controllably actuates the proportional driver circuits and the binary driver circuits. The apparatus detects failure conditions on the proportional driver circuits and the binary driver circuits and responsively produces respective failure condition signals. The apparatus is adapted to perform a proportional diagnostics routine on the proportional driver circuits and to perform a binary diagnostics routine on the binary driver circuits via the failure conditions detecting means.

Solenoid driver circuit and diagnostics

Vehicles having implements are typically used to perform repetitive functions in work cycles. An implement control system raises and lowers an implement relative to the vehicle and reduces the stresses applied to the vehicle from abruptly stopping the motion of the implement. A lever pilot signal is produced in response to the pivotal position of a control lever. An electrohydraulic pilot signal is also produced. The pilot signal having the greater pressure is directed to a main valve for controlling the position of the implement. The method and apparatus of the instant invention are applicable to a number of vehicles having a hydraulically operated implement.

Method and apparatus for controlling an implement

A communications network is adapted to provide communication between control modules on a vehicle. Each control module includes a first and second transceiver. A control module checks for the presence of a data message from another control module before transmitting a data message. If there is no other data message present, the control module transmits the data message around the network in both directions using the first and second transceivers. The other control modules receive the data message from the previous control module and pass the data message to the next control module in the network.

Fault tolerant serial communications network

An electrical transmission control mechanism includes first and second control members which are individually limitedly rotatable to respectively select the directional and neutral modes or the speed ratio modes of a transmission. First and second electrical rotary type switching devices which are respectively responsive to the movement of the control members are disposed within the mechanism for controllably disconnecting the supply and ground side leads of one of a plurality of transmission clutch actuating solenoids and connecting the supply and ground side leads of another one to minimize the possibility of any inadvertent electrical short in causing unexpected operation of the transmission. Each of the compact and reliable rotary switching devices has a plurality of upstanding contact members arranged at preselected radii and a plurality of radially oriented wiper members that make selected contact with pairs of the contact members to provide a multitude of desirable operating functions. The mechanism features a simple and yet rugged arrangement of the control members and the switching devices that is easy to operate.

Electrical transmission control mechanism

Anti-spin control systems are useful, for example, in industrial off-road vehicles. It is desirable that such systems exhibit rapid response to adverse working conditions, and be capable of quickly applying braking forces to whichever driven wheel is rotating at a higher velocity at a given time. The instant invention includes an electrical circuit for producing first and second brake control signals having values responsive to a working condition wherein one of the vehicle wheels loses traction and rotates more rapidly than the other vehicle wheel. A first controllable valve receives the first brake control signal and responsively controllably engages a brake mechanism associated with the faster rotating wheel, while a second controllable valve receives the second brake control signal and responsively controllably moves a brake mechanism associated with the slower rotating wheel from a brake released position to a brake pre-engaged position. Therefore, upon detecting a slippery working condition, each of the brake mechanisms associated with the driven wheels of the vehicle is brought into a state of readiness for immediate braking effort with minimal time delay.

Anti-spin control apparatus and method

Clutch-brake steering systems are known to operate on track vehicles which are highly reliable and cost effective, but lacked the fine degree of controllability found in the more expensive differential steering. An electronically controlled clutch-brake steering control apparatus provides control signals to electrohydraulic proportional valves for accurately modulating the control pressures of a set of steering clutches and brakes. A pair of sensors deliver signals, which are indicative of track speed, to the control apparatus. The apparatus acts to adaptively adjust selected ones of the valves to maintain a desired track speed differential. Thus, the controllability of the clutch-brake steering system is enhanced to effectively compete with more expensive and complex systems.

Clutch brake steering control

A hybridized solenoid driver circuit includes a first and second current sensing resistor. The first current sensing resistor is disposed within the flyback current path of the windings of an electrically actuated solenoid and provides a signal proportional to the flyback current only. Control of the solenoid current is effected by operation of a power transistor to controllably connect and disconnect the solenoid from the power supply at a preselected duty cycle. Operation of the driver circuit in the energization mode has no effect on the first current sensing resistor. Conversely, the second current sensing resistor is disposed within the energization current path and provides a signal proportional to the energization current only. Operation of the driver circuit in the flyback mode has no effect on the second current sensing resistor. A summing amplifier receives the first signal directly from the first current sensing resistor as it is referenced to ground; however, the second current sensing resistor is referenced to positive battery and the second signal must be passed through a current mirror prior to delivery to the summing amplifier. The signal provided by the summing amplifier is used by a control circuit to maintain the solenoid current at a desired level by constantly adjusting the duty cycle of a biasing signal delivered to the power transistor.

Dual current sensing driver circuit

Anti-wheel spin control systems are useful, for example, in industrial off-road vehicles. It is desirable that such systems operate automatically and not be unduly influenced by false slip signals caused by steering of the vehicle. It is further desirable that the operability of the control be readily determined by the operator. The instant anti-spin control includes an apparatus for producing a slip signal having a value responsive to the difference in rotational velocity between the vehicle wheels, and for producing a test signal. A processor receives the slip signal and test signal, compares the slip signal value with a first predetermined reference value in response to receiving the slip signal in the absence of the test signal, and compares the slip signal value with a second predetermined reference value in response to receiving both the slip signal and the test signal. A brake control signal is produced in response to the slip signal value exceeding the compared reference value, and the braking mechanism corresponding to the slipping wheel is activated. In a second embodiment of the invention, a steer signal is also produced and applied to the processor. The steer signal is utilized to negate the effect of steering the vehicle on the produced slip signal. Thus, the disclosed anti-spin system accounts for false slip indications produced by steering the vehicle, and provides a ready means for the operator to test the operability of the control system.

Multiple threshold wheel slip control apparatus and method

Pulse width modulated constant current servo driver

Failsafe wheel slip control system and method of operating same

Method and apparatus for controlling differentially driven wheel slip

Lift trucks (10) have many hand control levers which are manipulated to hoist a load, propel the lift truck (10) forward and rearward, and steer the lift truck (10). Some operations must be performed sequentially rather than simultaneously which increases loading time. An electronic directional control circuit (34) includes apparatus (36) for producing first and second command signals, apparatus (38) for producing first and second outputs in response to the first and second command signals, and apparatus (40) for delaying production of a preselected one of the first and second outputs a preselected time sufficient for the selected output to decrease to a preselected magnitude prior to the production of the other of the first and second outputs. The electronic directional control circuit (34) is useable with vehicles (10) which initiate the command signals with a foot operated pedal (12) while leaving the hands free for simultaneously operating other controls.

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Dunlap, IL, United States of America

Weldon L Phelps