Hydromechanical transmission

Claim 2

A hydromechanical transmission, comprising, a. an input shaft, b. an output shaft, c. a mechanical differential connected to the output shaft, d. a first hydraulic unit connected to the input shaft, e. a second hydraulic unit in closed hydraulic circuit with the first hydraulic unit and connected to the differential, f. a first clutch for connecting the second hydraulic unit to drive the output shaft in a low range hydrostatic mode, g. a second clutch for connecting the input shaft to the differential to drive the output shaft in a high range hydromechanical mode with split power paths through the second clutch and the hydraulic units, h. an engine for driving the input shaft including a throttle for controlling engine power, i. fluid operable means for varying the displacement of one of the hydraulic units to vary the speed of the output shaft relative to the input shaft, j. a governor valve for controlling the flow of control fluid relative to the displacement varying means to control displacement, k. acceleration control means for applying a predetermined resilient bias to the governor valve and simultaneously establishing an engine throttle setting to provide a predetermined engine speed, l. means providing a bias signal proportional to engine speed to the governor valve in opposition to the manual bias for establishing a transmission ratio for controlling eNgine speed, m. means for energizing the low range clutch, n. shift valve means for energizing the high range clutch and deenergizing the low range clutch to shift the transmission into the high range, and o. valve means responsive to the speed of the engine and providing a fluid pressure signal proportional to engine speed to operate the shift valve means at predetermined engine speed.

Claim 3

A transmission as defined in claim 1, wherein the engine speed responsive means comprises a valve having an inlet communicating with a source of charge fluid under pressure, an outlet for supplying fluid under pressure to the shift valve means, and a valve member controlling communication between the inlet and outlet responsive to the speed of the engine.

Claim 4

A transmission as defined in claim 2, including an outlet from the speed responsive valve means for supplying a fluid pressure signal proportional to engine speed to the governor valve in opposition to the manual bias.

Claim 5

A transmission as defined in claim 2, including a pressure regulating valve for supplying control fluid under pressure to the governor valve, and an outlet from said engine speed responsive valve means for supplying a fluid pressure signal to the pressure regulating valve for establishing maximum control fluid pressure at a predetermined engine speed.

Claim 6

A transmission as defined in claim 1, including a shift valve for energizing the high range clutch, a shift qualifying valve controlled by the engine speed responsive valve for delivering fluid to pressurize the shift valve at a predetermined engine speed, valving controlled by the shift valve for supplying a signal to reset the shift qualifying valve preparatory for downshift, and means for delaying the reset signal from the shift valve to the shift qualifying valve to prevent immediate downshift due to transitory signals.

Claim 7

A transmission as defined in claim 5, wherein the delay means comprises a reshift delay valve, means normally biasing the valve to a position blocking communication between the shift valve and the shift qualifying valve, and a restricted passage from the shift valve to provide fluid under pressure at a limited rate for moving the valve member to a position communicating the shift valve and the shift qualifying valve.

Claim 8

A hydromechanical transmission, comprising, a. an input shaft, b. an output shaft, c. a mechanical differential connected to the output shaft, d. a first hydraulic unit connected to the input shaft, e. a second hydraulic unit in closed hydraulic circuit with the first hydraulic unit and connected to the differential, f. a first clutch for connecting the second hydraulic unit to drive the output shaft in a low range hydrostatic mode, g. a second clutch for connecting the input shaft to the differential to drive the output shaft in a high range hydromechanical mode with split power paths through the second clutch and the hydraulic units, h. an engine for driving the input shaft including a throttle for controlling engine power, i. fluid operable means for varying the displacement of one of the hydraulic units to vary the speed of the output shaft relative to the input shaft, j. a governor valve for controlling the flow of control fluid relative to the displacement varying means to control displacement, k. acceleration control means for applying a predetermined resilient bias to the governor valve and simultaneously establishing an engine throttle setting to provide a predetermined engine speed, l. means providing a bias signal proportional to engine speed to the governor valve in opposition to the manual bias for establishing a transmission ratio for controlling engine speed, m. means for energizing the low range clutch, n. a shift valve for energizing the high range clutch and deenergizing the low range clutch to shift the transmission into the high range, o. means for providing a bias urging the shift valve toward a positioN for providing high range operation, p. means providing a bias holding the shift valve in the position providing for low range operation, and q. means for sensing the speed of the input shaft and the speed of the output shaft and withdrawing the holding bias when the speed of the output shaft exceeds the speed of the input shaft.

Claim 9

A hydromechanical transmission, comprising, a. an input shaft, b. an output shaft, c. a mechanical differential connected to the output shaft, d. a first hydraulic unit connected to the input shaft, e. a second hydraulic unit in closed hydraulic circuit with the first hydraulic unit and connected to the differential, f. a first clutch for connecting the second hydraulic unit to drive the output shaft in a low range hydrostatic mode, g. a second clutch for connecting the input shaft to the differential to drive the output shaft in a high range hydromechanical mode with split power paths through the second clutch and the hydraulic units, h. an engine for driving the input shaft including a throttle for controlling engine power, i. fluid operable means for varying the displacement of one of the hydraulic units to vary the speed of the output shaft relative to the input shaft, j. a governor valve for controlling the flow of control fluid relative to the displacement varying means to control displacement, k. acceleration control means for applying a predetermined resilient bias to the governor valve and simultaneously establishing an engine throttle setting to provide a predetermined engine speed, l. means providing a bias signal proportional to engine speed to the governor valve in opposition to the manual bias for establishing a transmission ratio for controlling engine speed, m. means for energizing the low range clutch, n. a shift valve for energizing the high range clutch and deenergizing the low range clutch to shift the transmission into the high range, o. means for providing a bias urging the shift valve toward a positioN for providing high range operation, p. means providing a bias holding the shift valve in the position providing for low range operation, and q. means for sensing the speed of the input shaft and the speed of the output shaft and withdrawing the holding bias when the speed of the output shaft exceeds the speed of the input shaft.

Claim 10

A transmission as defined in claim 7, including means responsive to operation of the shift valve to the high range position for providing a holding signal for maintaining the shift valve in the high range position.

Claim 11

A transmission as defined in claim 7, including a synchronous speed sensor valve having an inlet communicating with a source of charge fluid under pressure, an outlet for supplying said holding bias to said shift valve, and a valve member normally positioned to communicate the inlet and outlet when the input shaft speed exceeds the output shaft speed and operative to communicate the outlet with drain when the output shaft speed exceeds the input shaft speed.

Claim 12

A transmission as defined in claim 7, including valve means responsive to the speed of the engine for providing said shifting bias to said shift valve at predetermined engine speed.

Claim 13

A transmission as defined in claim 10, wherein said engine speed responsive valve means includes a shift qualifying valve for supplying said shift bias to the shift valve, and a speed sensor valve for providing a signal to actuate the shift qualifying valve at a predetermined engine speed.

Claim 14

A transmission as defined in claim 11, including valving controlled by the shift valve on movement to the high range position for supplying a signal to reset the shift qualifying valve preparatory for downshift.

Claim 15

A transmission as defined in claim 12, including means for delaying the reset signal from the shift valve to the shift qualifying valve to prevent immediate downshift due to transitory signals.

Claim 16

A hydromechanical transmission, comprising, a. an input shaft, b. an output shaft, c. a mechanical differential connected to the output shaft, d. a first hydraulic unit connected to the input shaft, e. a second hydraulic unit in closed hydraulic circuit with the first hydraulic unit and connected to the differential, f. a first clutch for connecting the second hydraulic unit to drive the output shaft in a low range hydrostatic mode, g. a second clutch for connecting the input shaft to the differential to drive the output shaft in a high range hydromechanical mode with split power paths through the second clutch and the hydraulic units, h. an engine for driving the input shaft including a throttle for controlling engine power, i. fluid operable means for varying the displacement of one of the hydraulic units to vary the speed of the output shaft relative to the input shaft, j. a governor valve for controlling the flow of control fluid relative to the displacement varying means to control displacement, k. acceleration control means for applying a predetermined resilient bias to the governor valve and simultaneously establishing an engine throttle setting to provide a predetermined engine speed, l. means providing a bias signal proportional to engine speed to the governor valve in opposition to the manual bias for establishing a transmission ratio for controlling engine speed, m. means for energizing the low range clutch, n. shift valve means for energizing the high range clutch and deenergizing the low range clutch to shift the transmission into the high range, o. valve means responsive to the speed of the engine for providing a fluid pressure signal for operating the shift valve means, and p. a drive selector valve having a first position for communicating said fluid pressure signal from said speed responsive valve means to said shift valve means to permit automatic shifting to high range operation and a second position blocking communication between the speed responsive valve means and tHe shift valve means to prevent shifting to high range.

Claim 17

A hydromechanical transmission, comprising, a. an input shaft, b. an output shaft, c. a mechanical differential connected to the output shaft, d. a first hydraulic unit connected to the input shaft, e. a second hydraulic unit in closed hydraulic circuit with the first hydraulic unit and connected to the differential, f. a first clutch for connecting the second hydraulic unit to drive the output shaft in a low range hydrostatic mode, g. a second clutch for connecting the input shaft to the differential to drive the output shaft in a high range hydromechanical mode with split power paths through the second clutch and the hydraulic units, h. an engine for driving the input shaft including a throttle for controlling engine power, i. fluid operable means for varying the displacement of one of the hydraulic units to vary the speed of the output shaft relative to the input shaft, j. a governor valve for controlling the flow of control fluid relative to the displacement varying means to control displacement, k. acceleration control means for applying a predetermined resilient bias to the governor valve and simultaneously establishing an engine throttle setting to provide a predetermined engine speed, l. means providing a bias signal proportional to engine speed to the governor valve in opposition to the manual bias for establishing a transmission ratio for controlling engine speed, m. means for energizing the low range clutch, n. shift valve means for energizing the high range clutch and deenergizing the low range clutch to shift the transmission into the high range, o. valve means responsive to the speed of the engine for providing a fluid pressure signal for operating the shift valve means, and p. a drive selector valve having a first position for communicating said fluid pressure signal from said speed responsive valve means to said shift valve means to permit automatic shifting to high range operation and a second position blocking communication between the speed responsive valve means and tHe shift valve means to prevent shifting to high range.

Claim 18

A transmission as defined in claim 14, wherein the drive selector valve is movable to a third ''''neutral'''' position for communicating opposite sides of the displacement varying means to prevent transmission operation.

Claim 19

A transmission as defined in claim 14, wherein the drive selector valve is movable to a third position for inverting signals from the governor valve to the displacement varying means for obtaining transmission operation in reverse direction.

Claim 20

A hydromechanical transmission, comprising, a. an input shaft, b. an output shaft, c. a mechanical differential connected to the output shaft, d. a first hydraulic unit connected to the input shaft, e. a second hydraulic unit in closed hydraulic circuit with the first hydraulic unit and connected to the differential, f. a first clutch for connecting the second hydraulic unit to drive the output shaft in a low range hydrostatic mode, g. a second clutch for connecting the input shaft to the differential to drive the output shaft in a high range hydromechanical mode for split power paths through the second clutch and the hydraulic units, h. an engine for driving the input shaft including a throttle for controlling engine power, i. fluid operable means for varying the displacement of one of the hydraulic units to vary the speed of the output shaft relative to the input shaft, j. a governor valve for controlling the flow of control fluid relative to the displacement varying means to control displacement, k. acceleration control means for applying a predetermined resilient bias to the governor valve and simultaneously establishing an engine throttle setting to provide a predetermined engine speed, l. means providing a bias signal proportional to engine speed to the governor valve in opposition to the manual bias for establishing a transmission ratio for controlling engine speed, m. a sequence valve positionable for energizing the low range clutch, n. a shift valve positionable for energizing the high range clutch, o. a synchronous speed sensor valve providing a signal holding the shift valve in the low range position when the speed of the input shaft exceeds the speed of the output shaft and withdrawing the holding signal when the output shaft speed exceeds the input shaft speed, p. a shift qualifying valve responsive to engine speed for providing a signal to move the shift valve to the high range position when the engine attains a predetermined speed and the output shaft speed equals the input shaft speed, q. valving on the shift valve for porting fluid to shift the sequence valve to the high range position when the shift valve moves to the high range position and for porting fluid to shift the sequence valve to the low range position when the shift valve moves to the low range position, and r. valving on the sequence valve porting fluid to hold the sequence valve in the high range position when moved to the high range position and to hold the sequence valve in the low range position when moved to the low range position.

Claim 21

A hydromechanical transmission, comprising, a. an input shaft, b. an output shaft, c. a mechanical differential connected to the output shaft, d. a first hydraulic unit connected to the input shaft, e. a second hydraulic unit in closed hydraulic circuit with the first hydraulic unit and connected to the differential, f. a first clutch for connecting the second hydraulic unit to drive the output shaft in a low range hydrostatic mode, g. a second clutch for connecting the input shaft to the differential to drive the output shaft in a high range hydromechanical mode for split power paths through the second clutch and the hydraulic units, h. an engine for driving the input shaft including a throttle for controlling engine power, i. fluid operable means for varying the displacement of one of the hydraulic units to vary the speed of the output shaft relative to the input shaft, j. a governor valve for controlling the flow of control fluid relative to the displacement varying means to control displacement, k. acceleration control means for applying a predetermined resilient bias to the governor valve and simultaneously establishing an engine throttle setting to provide a predetermined engine speed, l. means providing a bias signal proportional to engine speed to the governor valve in opposition to the manual bias for establishing a transmission ratio for controlling engine speed, m. a sequence valve positionable for energizing the low range clutch, n. a shift valve positionable for energizing the high range clutch, o. a synchronous speed sensor valve providing a signal holding the shift valve in the low range position when the speed of the input shaft exceeds the speed of the output shaft and withdrawing the holding signal when the output shaft speed exceeds the input shaft speed, p. a shift qualifying valve responsive to engine speed for providing a signal to move the shift valve to the high range position when the engine attains a predetermined speed and the output shaft speed equals the input shaft speed, q. valving on the shift valve for porting fluid to shift the sequence valve to the high range position when the shift valve moves to the high range position and for porting fluid to shift the sequence valve to the low range position when the shift valve moves to the low range position, and r. valving on the sequence valve porting fluid to hold the sequence valve in the high range position when moved to the high range position and to hold the sequence valve in the low range position when moved to the low range position.

Claim 22

A transmission as defined in claim 7, including valving on the sequence valve for porting fluid to hold the shift valve in the high range position when moved to the high range position and to hold the shift valve in low range position when moved to the low range position.

Claim 23

A hydromechanical transmission, comprising, a. an input shaft, b. an output shaft, c. a mechanical differential connected to the output shaft, d. a first hydraulic unit connected to the input shaft, e. a second hydraulic unit in closed hydraulic circuit with the first hydraulic unit and connected to the differential, f. a first clutch for connecting the second hydraulic unit to drive the output shaft in a low range hydrostatic mode, g. a second clutch for connecting the input shaft to the differential to drive the output shaft in a high range hydromechanical mode with split power paths through the second clutch and the hydraulic units, h. an engine for driving the input shaft including a throttle for controlling engine power, i. fluid operable means for varying the displacement of one of the hydraulic units to vary the speed of the output shaft relative to the input shaft, j. a governor valve for controlling the flow of control fluid relative to the displacement varying means to control displacement, k. acceleration control means for applying a predetermined resilient bias to the governor valve and simultaneously establishing an engine throttle setting to provide a predetermined engine speed, l. means providing a bias signal proportional to engine speed to the governor valve in opposition to the manual bias for establishing a transmission ratio for controlling engine speed, m. means for energizing the low range clutch, n. shift valve means for energizing the high range clutch and deenergizing the low range clutch to shift the transmission into the high range, o. valve means responsive to the speed of the engine for providing a fluid pressure signal for operating the shift valve means, and p. means actuated when the high range clutch is actuated for applying a predetermined bias to the governor valve additional to the bias applied by the acceleration control means for holding a minimum setting on the governor even if the acceleration control is released.

Claim 24

A hydromechanical transmission, comprising, a. an input shaft, b. an output shaft, c. a mechanical differential connected to the output shaft, d. a first hydraulic unit connected to the input shaft, e. a second hydraulic unit in closed hydraulic circuit with the first hydraulic unit and connected to the differential, f. a first clutch for connecting the second hydraulic unit to drive the output shaft in a low range hydrostatic mode, g. a second clutch for connecting the input shaft to the differential to drive the output shaft in a high range hydromechanical mode with split power paths through the second clutch and the hydraulic units, h. an engine for driving the input shaft including a throttle for controlling engine power, i. fluid operable means for varying the displacement of one of the hydraulic units to vary the speed of the output shaft relative to the input shaft, j. a governor valve for controlling the flow of control fluid relative to the displacement varying means to control displacement, k. acceleration control means for applying a predetermined resilient bias to the governor valve and simultaneously establishing an engine throttle setting to provide a predetermined engine speed, l. means providing a bias signal proportional to engine speed to the governor valve in opposition to the manual bias for establishing a transmission ratio for controlling engine speed, m. means for energizing the low range clutch, n. shift valve means for energizing the high range clutch and deenergizing the low range clutch to shift the transmission into the high range, o. valve means responsive to the speed of the engine for providing a fluid pressure signal for operating the shift valve means, and p. means actuated when the high range clutch is actuated for applying a predetermined bias to the governor valve additional to the bias applied by the acceleration control means for holding a minimum setting on the governor even if the acceleration control is released.

Claim 25

A transmission as defined in claim 19, including a spring acting on the governor valve, a plunger engaging the spring for establishing a predetermined spring setting on operation of said acceleration control means, a sleeve surrounding the plunger and engaging the spring for establishing said additional bias, and valving on the shift valve means for porting fluid under pressure to actuate said sleeve when the high range clutch is energized.