Control system for split axle drive mechanism

Abstract

A part-time four-wheel drive vehicle has a transfer case and a split axle drive mechanism for the selectively driving two vehicle wheels. The slit axle drive mechanism has a clutch associated with one of the differential side gears for preventing back drive to the transfer case in the two-wheel drive mode. A control system for operating the clutch responsive to the operational mode of the transfer case comprises a vacuum motor and a solenoid operated two-way valve energized by way of a switch in the transfer case. The control system also includes a pneumatic time delay and a vacuum check valve.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. A control system for automatically operating the clutch in a single clutch split axle drive mechanism responsive to an operational mode of a transfer case, with which the split axle drive mechanism is used in a part-time four-wheel drive vehicle powered by an internal combustion engine, comprising: a vacuum motor mechanically connected to the clutch so that the clutch is biased toward disengagement when the vacuum motor is vented and biased toward engagement when the vacuum motor is evacuated,   conduit means connecting the vacuum motor to a vacuum source provided by the internal combustion engine,   said conduit means including a two-way valve which has a first operative position when the vacuum motor is connected to a vent and a second operative position where the vacuum motor is connected to the vacuum source for evacuating the vacuum motor,   means operatively connected to the transfer case positioning the two-way valve in the second operative position when the transfer case is in a four-wheel drive mode whereby the clutch is automatically engaged when four-wheel drive is selected, and   said two-way valve being mechanically positioned in the fist operative position when the transfer case is in the two-wheel drive mode whereby the control system does not require any power for operation in the two-wheel drive mode.   
     
     
       2. A control system for automatically operating the clutch in a single clutch split axle drive mechanism responsive to an operational mode of a transfer case, with which the split axle drive mechanism is used in a part-time four-wheel drive vehicle powered by an internal combustion engine, comprising: a vacuum motor operatively connected to the clutch so that the clutch is biased toward disengagement when the vacuum motor is vented and biased toward engagement when the vacuum motor is evacuated,   conduit means connecting the vacuum motor to a vacuum source provided by the internal combustion engine,   said conduit means including a two-way valve which has a first operative position where the vacuum motor is vented and a second operative position where the vacuum motor is evacuated by the vacuum source,   means positioning the two-way valve in the second position when the transfer case is in a four-wheel drive mode whereby the clutch is automatically engaged when four-wheel drive is selected, and   time delay means in the conduit means for delaying clutch engagement to a time after the transfer case is shifted to four-wheel drive, so that the clutch parts are rotating in the same direction and four-wheel drive can be selected while the vehicle is in motion.   
     
     
       3. A control system for automatically operating the clutch in a single clutch split axle drive mechanism responsive to an operational mode of a transfer case, with which the split axle drive mechanism is used in a part-time four-wheel drive vehicle powered by an internal combustion engine, comprising: a vacuum motor mechanically connected to the clutch so that the clutch is biased toward disengagement when the vacuum motor is vented and biased toward engagement when the vacuum motor is evacuated,   conduit means connecting the vacuum motor to the intake manifold of the internal combustion engine for evacuating the vacuum motor,   said conduit means including a two-way valve which has a first operative position where the vacuum motor is vented and a second operative position where the vacuum motor is connected to the vacuum source,   electric means operatively connected to the transfer case positioning the two-way valve in the second operative position when the transfer case is in a four-wheel drive mode whereby the clutch is automatically engaged when four-wheel drive is selected, and   a vacuum check valve in the conduit means between the two-way valve and the intake manifold for preventing bleed down of the evacuated vacuum motor by the intake manifold.   
     
     
       4. A control system for automatically operating the clutch in a single clutch split axle drive mechanism responsive to an operational mode of a transfer case, with which the split axle drive mechanism is used in a part-time four-wheel drive vehicle powered by an internal combustion engine, comprising: a vacuum motor mechanically connected to the clutch so that the clutch is biased toward disengagement when the vacuum motor is vented and biased toward engagement when the vacuum motor is evacuated,   conduit means connecting the vacuum motor to the intake manifold of the internal combustion engine for evacuating the vacuum motor,   said conduit means including a two-way valve which has a first operative position where the vacuum motor is vented and a second operative position where the vacuum motor is connected to the vacuum source,   spring means positioning the valve in the first operative position,   electric means positioning the two-way valve in the second operative position when the transfer case is in a four-wheel .Iadd.drive .Iaddend.mode whereby the clutch is automatically engaged when four-wheel drive is selected,   pneumatic time delay means in the conduit means between the vacuum motor and the two-way valve for delaying the clutch engagement for a predetermined mininum amount of time after the transfer case is shifted to four-wheel drive so that the clutch parts are rotating in the same direction when four-wheel drive is selected while the vehicle is in motion, and   a vacuum check valve in the .[.condition.]. .Iadd.conduit .Iaddend.means between the two-way valve and the intake manifold for preventing bleed down of the evacuated vacuum motor by the intake manifold.   
     
     
       5. In a part-time four-wheel drive vehicle having a source of vacuum, a transfer case having a two-wheel drive operating mode and a four wheel drive operating mode, and a split axle drive mechanism having a single clutch moveable between disengaged and engaged positions for the two-wheel drive and four-wheel drive operating modes, respectively, a control system for automatically operating the clutch responsive to the operational mode of the transfer case, comprising:   a vacuum motor,   means operatively connecting the vacuum motor to the clutch for biasing the clutch toward the engaged position when the vacuum motor is evacuated, and biasing the clutch toward the disengaged position when the vacuum motor is vented to atmosphere,   conduit means connected between the vacuum motor and the vacuum source,   said conduit means including valve means moveable between first and second positions for alternately connecting the conduit means to atmosphere or to the vacuum source,   means normally locating the valve means in the first position to connect the conduit means to atmosphere and maintain the clutch disengaged,   signal means actuated by the transfer case when in the four-wheel drive operating mode for indicating such mode to the vehicle operator,   and means actuated by the transfer case concurrently with actuation of the signal means for moving the valve means to the second position to connect the vacuum motor to the vacuum source and evacuate the vacuum motor to bias the clutch toward the engaged position when the transfer case is in the four-wheel drive operating mode,   and time delay means delaying evacuation of the vacuum motor by the vacuum source to a time after the transfer case is in the four-wheel drive operating mode so that the clutch parts are rotating in the same direction and four-wheel drive can be selected while the vehicle is in motion.   
     
     
       6. A control system for automatically operating the clutch in a single clutch split axle drive mechanism responsive to an operational mode of a transfer case, with which the split axle drive mechanism is used in a part-time four-wheel drive vehicle powered by an internal combustion engine, comprising: a vacuum motor operatively connected to the clutch so that the clutch is biased toward disengagement when the vacuum motor is vented and biased toward engagement when the vacuum motor is evacuated,   conduit means connecting the vacuum motor to a vacuum source provided by the internal combustion engine,   said conduit means including a two-way valve which has a first operative position where the vacuum motor is vented and a second operative position where the vacuum motor is evacuated by the vacuum source,   means positioning the two-way valve in the second position when the transfer case is in a four-wheel drive mode whereby the clutch is automatically engaged when four-wheel drive is selected, and   time delay means for delaying clutch engagement to a time after the transfer case is shifted to four-wheel drive, so that the clutch parts are rotating in the same direction and four-wheel drive can be selected while the vehicle is in motion.   
     
     
       7. A control system for automatically operating the clutch in a single clutch split axle drive mechanism responsive to an operational mode of a transfer case, with which the split axle drive mechanism is used in a part-time four-wheel drive vehicle powered by an internal combustion engine, comprising: a vacuum motor mechanically connected to the clutch so that .[.that.]. clutch is biased toward disengagement when the vacuum motor is vented and .[.baised.]. .Iadd.biased .Iaddend.toward engagement when the vacuum motor is evacuated,   conduit means connecting the vacuum motor to the intake manifold of the internal combustion engine for evacuating the vacuum motor,   said conduit means including a two-way valve which has a first operative position where the vacuum motor is vented and a second operative position where the vacuum motor is connected to the vacuum source,   spring means positioning the valve in the first operative position,   means positioning the two-way valve in the second operative position when the transfer case is in a four-wheel drive mode whereby the clutch is automatically engaged when four-wheel drive is selected,   pneumatic time delay means for delaying the clutch engagement for a predetermined minimum amount of time after the transfer case is shifted to four-wheel drive so that the clutch parts are rotating in the same direction when four-wheel drive is selected while the vehicle is in motion, and   a vacuum check valve in the conduit means between the two-way valve and the intake manifold for preventing bleed down of the evacuated vacuum motor by the intake manifold.   
     
     
       8. In a part-time four-wheel drive vehicle having a source of vacuum, a transfer case having a two-wheel drive operating mode and a four-wheel drive operating mode, and a split axle drive mechanism having a single clutch moveable between disengaged and engaged positions for the two-wheel drive and four-wheel drive operating modes, respectively, a control system for automatically operating the clutch responsive to the operational mode of the transfer case, comprising:   a vacuum motor;   means operatively connecting the vacuum motor to the clutch for biasing the clutch toward the engaged position when the vacuum motor is evacuated, and biasing the clutch toward the disengaged position when the vacuum motor is vented to atmosphere,   conduit means connected between the vacuum motor and the vacuum source,   said conduit means including valve means moveable between first and second positions for alternately connecting the conduit means to atmosphere or to the vacuum source,   means normally locating the valve means in the first position to connect the conduit means to atmosphere and maintain the clutch disengaged,   means actuated by the transfer case for moving the valve means to the second position to connect the vacuum motor to the vacuum source and evacuate the vacuum motor to bias the clutch toward the engaged position when the transfer case is in the four-wheel drive operating mode,   and time delay means delaying evacuation of the vacuum motor by the vacuum source to a time after the transfer case is in the four-wheel drive operating mode so that the clutch parts are rotating in the same direction and four-wheel drive can be selected while the vehicle is in motion. .Iadd.   
     
     
       9.  A control system for automatically operating the clutch in a single clutch split axle drive mechanism responsive to an operational mode of a transfer case, with which the split axle drive mechanism is used in a part-time four-wheel drive vehicle powered by an internal combustion engine comprising: a motor operatively connected to the clutch so that the clutch is biased toward disengagement when a first signal is communicated to the motor and biased toward engagement when a second signal is communicated to the motor,   control means having a first operative position where the first signal is communicated to the motor and a second operative position where the second signal is communicated to the motor,   means positioning the control means in the second operative position when the transfer case is in a four-wheel drive mode whereby the clutch is automatically engaged when four-wheel drive is selected, and   time delay means for delaying clutch engagement to a time after the transfer case is shifted to four-wheel drive, so that the clutch parts are rotating in the same direction and four-wheel drive can be selected while the vehicle is in motion. .Iaddend. .Iadd.   
     
     
       10.  A control system for automatically operating the clutch in a single clutch split axle drive mechanism responsive to an operational mode of a transfer case, with which the split axle drive mechanism is used in a part-time four-wheel drive vehicle powered by an internal combustion engine comprising: a fluid motor operatively connected to the clutch so that the clutch is biased toward disengagement when a first pressure condition is communicated to the fluid motor and biased toward engagement when a second pressure condition is communicated to the fluid motor,   conduit means connecting the fluid motor to a fluid pressure source,   said conduit means including a valve which has a first operative position where the first pressure condition is communicated to the fluid motor and a second operative position where the second pressure condition is communicated to the fluid motor,   means positioning the valve in the second operative position when the transfer case is in a four-wheel drive mode whereby the clutch is automatically engaged when four-wheel drive is selected, and   time delay means for delaying clutch engagement to a time after the transfer case is shifted to four-wheel drive, so that the clutch parts are rotating in the same direction and four-wheel drive can be selected while the vehicle is in motion. .Iaddend. .Iadd.   
     
     
       11.  A control system enabling selection of four-wheel drive during two-wheel driven motion of a vehicle having a transfer case which includes a clutch or the like actuable to drivingly connect engine torque with a propeller shaft connected with the differential input of a differentially split axle drive mechanism having a first differential output drive coupled with a first wheel and a second differential output disconnectably coupled to a second wheel by an axle clutch enabling the two-wheel drive mode to include disconnection of the axle clutch as well as deactuation of the transfer case clutch so that the propeller shaft and differential input remain at fuel and wear saving rest while the road driven first wheel back drives the second differential output in counterrotation relative to the second wheel, said control system comprising: motor means connected to the axle clutch to actuate the axle clutch to connectably couple the second differential output and the second wheel, and control means operably associated with the transfer case and adapted to operate the motor means and effect axle clutch engagement, said control means having associated time delay means so that axle clutch engagement occurs subsequent to actuation of the transfer case clutch or the like to provide engine driven rotation of the then resting propeller shaft and the differential input and provide reversal of the counterrotation of the second differential output into same direction rotation with the second wheel at a substantially synchronized rate therewith whereby four-wheel drive can be selected while the vehicle is in two-wheel drive motion. .Iaddend. .Iadd.   
     
     
       12.  A control system enabling selection of four-wheel drive during two-wheel driven motion of a vehicle having a transfer case which includes a clutch or the like actuable to drivingly connect engine torque with a propeller shaft connected with the differential input of a differentially split axle drive mechanism having a first differential output drive coupled with one wheel and a second differential output disconnectably coupled to a second wheel by an axle clutch enabling the two-wheel drive mode to include disconnection of the axle clutch as well as deactuation of the transfer case clutch so that the propeller shaft and differential input remain at fuel and wear saving rest while the road driven first wheel back drives the second differential output in counterrotation relative to the second wheel, said control system comprising: motor means operatively connected to the axle clutch for engaging the axle clutch;   motor control means adapted to operate the motor means to engage the axle clutch in response to four-wheel drive selection and attendant actuation of the transfer case clutch to thereby connectably couple the second differential output with the second wheel; and   means for delaying the axle clutch engagement for an amount of time subsequent to transfer case clutch actuation to enable initiation of engine driven rotation of the then resting propeller shaft and differential input and concomitant reversal of the counterrotation of the second differential output into rotation in the same direction with the second wheel and at a substantially synchronized rate therewith whereby the transfer case clutch and axle clutch can be selected to their respective four-wheel drive operating modes while the vehicle is in motion. .Iaddend. .Iadd.13. A control system enabling selection of four-wheel drive during two-wheel driven motion of a vehicle having a transfer case which includes a clutch or the like actuable to drivingly connect engine torque with a propeller shaft connected with the differential input of a differentially split axle drive mechanism having a first differential output coupled with one wheel and a second differential output disconnectably coupled to a second wheel by an axle clutch enabling the two-wheel drive mode to include disconnection of the axle clutch as well as deactuation of the transfer case clutch so that the propeller shaft and differential input remain at fuel and wear saving rest while the road driven first wheel back drives the second differential output in counterrotation relative to the second wheel, said control system comprising:   a fluid motor operatively connected to the axle clutch so that the axle clutch is disengaged in response to a first fluid pressure condition and engaged in response to a second fluid pressure condition;   valve means having a first operative position to communicate the first fluid pressure condition to the fluid motor and a second operative position for communicating the second fluid pressure condition to the fluid motor;   means positioning the valve means in the second operative position when the transfer case clutch is engaged whereby the axle clutch is automatically engaged in response to engagement of the transfer case clutch and attendant engine driven rotation of the propeller shaft and differential input; and   means for delaying axle clutch engagement to a time after the transfer case clutch is engaged to assure reversal of the counterrotation of the second differential output and rotation of the second differential output at a substantially synchronized rate with the second wheel whereby the axle clutch can be engaged while the vehicle is in motion. .Iaddend.