Case Corporation

Craig R Eike

Guy T Stoever

Kevin Douglas McKee

Bradley A Nielsen

A work vehicle configured for selectively applying power to a load and comprising a frame, a plurality of ground support devices movably secured to the frame, an engine supported by the frame, a source of hydraulic fluid at a pressure, a clutch for selectively coupling the engine to the load in response to a control signal, the clutch including a clutch actuator configured for engaging the clutch upon receipt of an actuating fluid at least a first predetermined pressure, the clutch configured to dissipate heat of engagement to a flow of a lube fluid; and a clutch control valve located intermediate the fluid source and the clutch and disposed in the path of the actuating fluid and the lube fluid. The control valve is configured to control flow of the lube fluid to the clutch to a first predetermined rate while the clutch is not engaged, to control flow of the lube fluid to the clutch to a second predetermined rate at least for a predetermined length of time prior to engagement of the clutch, and to control flow of the actuating fluid at a predetermined pressure to the clutch actuator after the flow rate of the lube fluid has been increased.

Clutch control valve

An apparatus and method is disclosed for controlling engagement of a power take-off shaft (PTO) on a vehicle. The apparatus includes a clutch including an input shaft coupled to a power source and an output shaft coupled to the PTO. The apparatus also includes an input speed sensor for sensing a quantity related to the angular velocity of the input shaft, an output shaft speed sensor for sensing angular velocity of the output shaft, and a clutch controller for adjusting pressure of hydraulic fluid applied to the clutch in response to control signals. Torque transmitted between the input and output shafts is responsive to the control signals. The apparatus also includes a control circuit coupled to the speed sensors and the clutch controller. The control circuit is configured to receive signals from the speed sensors and to provide the control signals in response thereto. During engagement of the PTO, the control circuit continuously determines an actual acceleration of the PTO based upon the output shaft velocity, and generates the control signals using a desired acceleration and the actual acceleration. The control circuit may continuously determine the desired acceleration based upon the input speed signal. Alternatively, the control circuit may provide control signals to cause the torque transmitted through the clutch to increase at a rate depending upon the difference between the desired and actual accelerations when the actual acceleration is more than a threshold proportion of the desired acceleration, and to cause the torque to increase at a rate independent of the difference when the actual acceleration is less than the threshold proportion.

Power take-off engagement control system

There is provided in accord with the present invention a work vehicle having a transmission and a clutch control system controlling the vehicle clutches, with the clutch control system including a flow restrictor assembly. The flow restrictor assembly comprises a modulator valve and an unloading valve in fluid communication with the fluid supply and the clutch control system. The unloading valve is selectively in fluid communication with the modulator valve through a modulator tank orifice and is responsive to fluid pressure changes acting on the modulator valve, as the clutch control system operates to control the length of time the modulator valve regulates the rate of flow of fluid to the clutch control system through the modulator tank orifice. In one embodiment the unloading valve spool is nested inside the modulator valve spool.

Flow restrictor assembly in transmission clutch control system

A simplified brake control system comprises a source of pressurized fluid, a spring-set brake with a hydraulic release mechanism and a control valve connected between the brake and the source. The control valve has a valve body and a flow control mechanism in the body and mounted for movement between a first (solenoid-energized) position and a second (solenoid-de-energized) position. A one-way check valve is built into the valve body. How the system operates depends upon two factors, namely, (a) whether the valve flow control mechanism is in its first or its second position, and (b) the relationship of the pressure of the source, i.e., the first pressure, and the second pressure in the release mechanism. When the flow control mechanism is in the first position, the release mechanism may be pressurized for brake release. And when such mechanism is in the second position, the release mechanism is vented to the reservoir through the brake port, the second passage and the drain port. A new method for controlling a brake is also disclosed.

Brake control system and related method

In a vehicle having a power shift transmission engageable in a plurality of forward gear ratios by engaging and disengaging first and second fluid clutches with a fluid from a fluid supply, a manifold apparatus for measuring a pressure of the fluid and simultaneously filling the first and second clutches with the fluid supply having a first clutch fill valve fluidly coupled to the first clutch to control the flow of the fluid to the first clutch; a second clutch fill valve fluidly coupled to the second clutch to control the flow of the fluid to the second clutch; a manifold fluidly coupled to the first and second clutch valves to conduct the fluid from the fluid supply to the first and second clutch valves; a first flow restrictor disposed between the manifold and the fluid supply to restrict the flow of the fluid from the fluid supply to the manifold; and a pressure transducer fluidly communicating with the manifold to generate a signal representative of the pressure of the fluid within the manifold, where the first and second clutches are not simultaneously engaged to provide any of the plurality of forward gear ratios.

Manifold apparatus for calibrating clutch fill times

This invention includes an apparatus for calibrating fluid clutch fill times including a valve, a clutch connected to the valve, a fluid supply connected to the valve, a pressure transducer connected between the fluid supply and the valve, and a processor adapted to control the valve, read the pressure transducer, and calculate the time required to fill the clutch. The invention further includes a method for adaptively controlling clutch engagement and disengagement in a clutch control system including signalling a first clutch valve to fill a clutch, measuring the time required to fill the clutch, signalling a second clutch valve to empty a second clutch, and saving the time value. The invention also includes a transmission system for a work vehicle that includes a transmission, two fluid clutches that engage the transmission in two gear ratios, respectively and a transmission controller that will calibrate the clutches and shift the transmission while the vehicle is in motion by engaging one clutch and disengaging another clutch while calculating the time required to fill the first clutch.

Method and apparatus for calibrating clutch fill rates

A 2-position, 3-way directional control valve is described which prevents reverse flow from an actuator port to a pressure port in one position. In the preferred embodiment described, the valve is solenoid actuated and is spring biased to a drain position, wherein an extension central to a spool assembly penetrates through a check valve seat and lifts a check valve ball from its seat to permit flow from an actuator port to a drain port. In the actuated or energized position, an armature assembly is shifted by a solenoid, drawing the spool assembly within the valve body and establishing a fluid path between a pressure port and the actuator port. In this position the extension of the spool assembly is withdrawn from the check valve seat. The check valve can be unseated by pressure from the pressure port to permit flow from the pressure port, through the spool and the check valve assembly. In the event of loss of pressure from the pressure port, such as due to shifting of other valves coupled to a pressure source, the check valve reseats to prevent reverse flow from the actuator port to the pressure port. The valve assembly is preferably configured as a cartridge valve for use in pre-drilled manifolds.

Growing community of inventors

DeKalb, IL, United States of America

Craig R Eike