Electronic control system for powershift transmission with compensation for variation in supply voltage

• US 5,053,960 A
• Filed: 08/27/1990
• Issued: 10/01/1991
• Est. Priority Date: 05/29/1987
• Status: Expired due to Term

• Current Assignee: Blue Leaf IP Incorporated (CNH Industrial N.V.), CNH America Llc (CNH Industrial N.V.)
• Original Assignee: JI Case Company (CNH Industrial N.V.)
• Inventors: Thomas, John C., Brekkestran, Kevin L.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US07/572,285
• Time in Patent Office: 400 Days
• Field of Search: 364/424.1, 74/866
• US Class Current: 701/51
• CPC Class Codes: B60W 2540/14 Clutch pedal position
• CPC Class Codes: F16D 2048/0281 Complex circuits with more than two valves in series or special arrangements thereof not provided for in previous groups
• CPC Class Codes: F16D 2500/1022 Electromagnet
• CPC Class Codes: F16D 2500/1026 Hydraulic
• CPC Class Codes: F16D 2500/111 Agricultural
• CPC Class Codes: F16D 2500/1112 Heavy vehicle
• CPC Class Codes: F16D 2500/3069 Engine ignition switch
• CPC Class Codes: F16D 2500/31413 Clutch pedal position
• CPC Class Codes: F16D 2500/3146 input from levers
• CPC Class Codes: F16D 2500/31473 Parking brake lever
• CPC Class Codes: F16D 2500/5014 Filling the actuator cylinder with fluid
• CPC Class Codes: F16D 2500/50239 Soft clutch engagement
• CPC Class Codes: F16D 2500/5128 Driver workload reduction
• CPC Class Codes: F16D 2500/70217 Pressure
• CPC Class Codes: F16D 2500/70252 Clutch torque
• CPC Class Codes: F16D 2500/70282 Time
• CPC Class Codes: F16D 2500/7042 Voltage
• CPC Class Codes: F16D 2500/70605 Adaptive correction; Modifying control system parameters, e.g. gains, constants, look-up tables
• CPC Class Codes: F16D 2500/70663 State analysis; Analysing potential states of the machine and developing control strategies at each state
• CPC Class Codes: F16D 2500/7109 Pulsed signal; Generating or processing pulsed signals; PWM, width modulation, frequency or amplitude modulation
• CPC Class Codes: F16D 48/062 : of a clutch system with a plurality of fluid actuated clutches
• CPC Class Codes: F16D 48/068 : using signals from a manually actuated gearshift linkage
• CPC Class Codes: F16H 2059/088 : Fast forward-reverse-sequence mode
• CPC Class Codes: F16H 2061/0258 : Proportional solenoid valve
• CPC Class Codes: F16H 2061/0444 : during fast shifting over two gearsteps, e.g. jumping from fourth to second gear
• CPC Class Codes: F16H 59/56 : dependent on signals from the main clutch
• CPC Class Codes: F16H 59/72 : dependent on oil characteristics, e.g. temperature, viscosity
• CPC Class Codes: F16H 61/0206 : Layout of electro-hydraulic control circuits, e.g. arrangement of valves for control of actuators selecting and moving final output members, e.g. shift forks F16H61/2807
• CPC Class Codes: F16H 61/0246 : characterised by initiating reverse gearshift
• CPC Class Codes: F16H 61/061 : using electric control means
• CPC Class Codes: F16H 61/08 : Timing control
• CPC Class Codes: F16H 61/684 : without interruption of drive
• CPC Class Codes: F16H 61/70 : specially adapted for change-speed gearing in group arrangement, i.e. with separate change-speed gear trains arranged in series, e.g. range or overdrive-type gearing arrangements

Abstract

A microprocessor-based electronic control system for a powershift transmission having at least one proportional actuator, such as a solenoid-operated proportional valve, is disclosed. The controller operates a plurality of on-off solenoid valves and the solenoid-operated proportional valve to provide operator-selected gear shifts in both forward and reverse directions having controlled clutch engagements achieved by modulations of clutch engagement pressure by the proportional valve. The key parameters associated with the gradual clutch engagement are all easily varied by the controller, most under program control during operation, to provide for optimized clutch engagements for smooth gearshifts. The key parameters include: fast-fill clutch delay, initial clutch engagement pressure, rate of increase of clutch engagement pressure, and the length of the reduced pressure clutch engagement interval. The electronic controller also automatically modifies selected parameters in accordance with sensed changes in temperature, magnetic flux coupling between solenoids, and variations in the voltage supply provided to the series combination of the solenoid coil of proportional valve and its solenoid driver circuit. Preferred methods of operating the electronic controller and powershift transmission are also disclosed.

Claims

1. An improved electronic control system for use with a powershift transmission having a plurality of hydraulically-actuated clutches and at least one solenoid-operated hydraulic valve means for adjusting at least one parameter within the transmission, such valve means including a solenoid coil to which a first electrical signal is applied, the electronic control system being of the type which includes electronic switching means connectable in series with the coil to form a series combination to which a D.C. supply voltage is applied across, the electronic control system including microprocessor means for operating the powershift transmission in accordance with operating parameters stored in the microprocessor means for:

determining the actual value of the supply voltage provided across the series combination of the solenoid coil and the electronic switching means;

determining the difference between the actual value of the supply voltage and a predetermined nominal voltage value of the supply voltage; and

adjusting the second signal in inverse proportion to the value of the difference, thereby compensating for variation in the supply voltage.

2. A method of operating a power-transmitting apparatus used in or with an off-road vehicle, the apparatus having at least one proportional actuator means for adjusting an operating parameter of the apparatus, the actuator means including a solenoid coil to which a first signal which is an alternating electrical signal is applied, the electronic control system being of the type which includes an electronic switching means connectable in series with the coil for applying the first signal to the coil, and control means for generating a second signal representing the desired operating point of the proportional actuator means, the method comprising:

providing a direct current (DC) voltage from the normal vehicle electrical power supply system across the series combination of solenoid coil and electronic switching means;

sensing the actual value of the DC voltage from the vehicle supply system;

determining the difference between the actual value of the DC voltage and a predetermined nominal voltage value of the DC voltage; and

promptly adjusting the second signal in inverse proportion to the value of the difference, thereby substantially simultaneously compensating for variations in the actual DC voltage as such variations occur.

3. A method as in claim 2, wherein the first and second signals are pulse width modulated signals and the method further comprises the step of:

generating the second signal by means of a programmable timing means which operates concurrently with and is controlled by the microprocessor means.