Control arrangement for four-wheel drive vehicles

Claim 2

A control arrangement for a four-wheel drive vehicle having a main axle provided with a first differential and having an auxiliary axle provided with a second differential, with the first differential driven directly and the second differential driven by coupling means having adjustable power transmission characteristics, comprising: adjustment on said coupling means for receiving a control signal and for adjusting the power transmission characteristics of the coupling means in response thereto; means for determining a vehicle driving speed; means for determining a desired power output; means for determining a magnitude of a desired traction force as a function of the vehicle driving speed and the desired power output; means for determining a vehicle driving resistance as a function of the vehicle driving speed; means for determining a magnitude of a traction force difference by subtracting the vehicle driving resistance from the magnitude of the desired traction force; and means for producing said control signal as a function of the traction force difference and for supplying said control signal to said adjustment means.

Claim 3

A control arrangement according to claim 1, further comprising means for communicating with at least one digital computer system used in the vehicle for at least one of control, measuring, and data processing purposes.

Claim 4

A control arrangement according to claim 2, wherein said means for communicating with a digital computer system comprises a digital bus system.

Claim 5

A control arrangement according to claim 1, wherein said control arrangement is implemented at least partially in hardware technology.

Claim 6

A control arrangement according to claim 1, further comprising self-testing means for monitoring an operating condition of the control arrangement, and means for indicating an error condition.

Claim 7

A control arrangement according to claim 1, further comprising means for manually adjusting the power transmission characteristics of the coupling means independently of said control signal.

Claim 8

A control arrangement according to claim 1, wherein the four-wheel drive vehicle has an additional gear box or differential with adjustable power transmission characteristics, and further comprising means on said additional gear box or differential for receiving said control signal and for adjusting the power transmission characteristics in response thereto.

Claim 9

A control arrangement according to claim 1, wherein said means for determining a vehicle driving speed includes means for determining a mean value of the speeds of the wheels of the auxiliary driving axle.

Claim 10

A control arrangement according to claim 1, wherein the differential which drives the main axle is a transverse differential having a pair of output shafts and adjustable power transmission characteristics, and wherein said arrangement further comprises: means on said transverse differential for receiving said control signal and for adjusting the power transmission characteristics of the transverse differential in response thereto; means for determining a speed difference of the output shafts of the transverse differential; means for producing a control value as a function of the speed difference of the output shafts; and means for varying said control signal as a function of said control value and for supplying said control signal to the means for adjusting the characteristics of the transverse differential.

Claim 11

A control arrangement according to claim 1, wherein the auxiliary axle is provided with a self locking differential.

Claim 12

A control arrangement according to claim 1, wherein the auxiliary axle is provided with a transverse differential having a pair of output shafts and adjustable power transmission characteristics, and wherein said arrangement further comprises: means on said transverse differential for receiving said control signal and for adjusting the power transmission characteristics of the transverse differential in response thereto; means for determining a speed difference of the output shafts of the transverse differential; and means for producing a control value as a function of the speed difference of the output shafts; and means for varying said control signal as a function of said control value and for supplying said control value to the means for adjusting the characteristics of the transverse differential.

Claim 13

A control arrangement according to claim 1, wherein the first and the second differential are driven by a torque splitting gear box or differential with adjustable power transmission characteristics, and further comprising means on said additional gear box or differential for receiving said control signal and for adjusting the power transmission characteristics in response thereto.

Claim 14

A control arrangement according to claim 1, wherein said means for producing said control signal includes means for producing at least one intermediate control value as a function of the magnitude of the traction force difference, and means producing said control signal as a function of said intermediate control value.

Claim 15

A control arrangement according to claim 13, wherein said means for determining a magnitude of a desired traction force includes: means for determining a desired power output as a function of an engine speed and a throttle value angle of a gas pedal angle, and means for combining the desired power output and the vehicle driving speed to determine the desired traction force.

Claim 16

A control arrangement according to claim 14, wherein said desired power output is determined as a function of at least one of a turbo-charger boost pressure and inlet air temperature.

Claim 17

A control arrangement according to claim 14, wherein said means for combining the desired power output and the vehicle driving speed includes means for dividing the desired power output by the driving speed when the driving speed exceeds a predetermined minimum level, and wherein the resulting desired traction force is limited to a predetermined maximum value.

Claim 18

A control arrangement according to claim 16, wherein said dividing means includes means for dividing the desired power output by the predetermined minimum level when the driving speed is below said minimum level.

Claim 19

A control arrangement according to claim 13, further comprising adjusting means for producing an adjusting control value, and means for combining said adjusting control value and said intermediate control value to produce said control signal.

Claim 20

A control arrangement according to claim 18, wherein said combining means includes means for combining said adjusting and intermediate control values in a weighted sum relationship.

Claim 21

A control arrangement according to claim 18, wherein said combining means includes means for selecting a maximum value of said adjusting and intermediate control values.

Claim 22

A control arrangement according to claim 13, wherein said means for producing an intermediate control value includes means for setting said intermediate control value equal to a predetermined minimum value as the magnitude of the traction force difference approaches zero, means for increasing the intermediate control value at a rate as the magnitude of the traction force difference increases, and means for setting said intermediate control value equal to a predetermined maximum value when the magnitude of the pulling force difference exceeds a predetermined level.

Claim 23

A control arrangement according to claim 21, further comprising adjusting means for producing an adjusting control value, and means for varying at least one of said predetermined minimum value, said rate of increase, and said predetermined maximum value as a function of said adjusting control value.

Claim 24

A control arrangement according to claim 21, wherein said adjustment means on said coupling means adjusts the power transmission characteristics of the coupling means such that a traction force is distributed to the main axle and the auxiliary axle in correspondence with a ratio of a stationary axle load distribution when said intermediate control value is equal to said predetermined maximum value.

Claim 25

A control arrangement according to claim 13, wherein said means for producing an intermediate control value includes means for setting said intermedaite control value equal to a constant value.

Claim 26

A control arrangement according to claim 24, further comprising adjusting means for producing an adjusting control value, and means for varying said constant value as a function of said adjusting control value.

Claim 27

A control arrangement according to claim 13, wherein said means for producing an intermediate control value includes means for varying said intermediate control value as a linear fnction of the magnitude of the traction foce difference.

Claim 28

A control arrangement according to claim 26, further comprising adjusting means for producing an adjusting control value, and means for changing the linear relationship existing between the magnitude of the traction force difference and the intermediate control value.

Claim 29

A control arrangement according to claim 13, further comprising adjusting means for producing an adjusting control value, means for sensing a coefficient of friction between wheels of the main and auxiliary axles and a road surface by adjusting said adjusting means, and means for varying said intermediate control value as a function of the coefficient of friction.

Claim 30

A control arrangement according to claim 28, wherein said adjusting means can be adjusted by a driver of the vehicle.

Claim 31

A control arrangement according to claim 1, wherein said four-wheel drive vehicle is equipped with an anti-locking braking system, and wherein said control arrangement includes means for receiving a signal from the anti-locking braking system during a braking operation, and said means for producing said control signal is responsive to said signal from the anti-locking braking system.

Claim 32

A control arrangement according to claim 1, further comprising display means in a dashboard of the vehicle for displaying a current condition of the control arrangement.

Claim 33

A control arrangement for a four-wheel drive vehicle having a main axle provided with a first differential and having an auxiliary axle provided with a second differential with the first differential driven directly and the second differential driven by coupling means having input and output shafts and adjustable between a plurality of power transmission characteristics between fully engaged and disengaged, comprising: adjustment means on said coupling means for receiving a control signal and for adjusting the power transmission characteristics of the coupling in response thereto; means for determining a speed difference of the input and output shafts of the coupling means; and means for producing said control signal as a function of the speed difference and for supplying said control signal to the adjustment means; wherein the control signal varies exponentially with the speed difference.

Claim 34

A control arrangement for a four-wheel drive vehicle having a main axle provided with a first differential and having an auxiliary axle provided with a second differential with the first differential driven directly and the second differential driven by coupling means having input and output shafts and adjustable between a plurality of power transmission characteristics between fully engaged and disengaged, comprising: adjustment means on said coupling means for receiving a control signal and for adjusting the power transmission characteristics of the coupling in response thereto; means for determining a speed difference of the input and output shafts of the coupling means; and means for producing said control signal as a function of the speed difference and for supplying said control signal to the adjustment means; wherein the control signal varies exponentially with the speed difference.

Claim 35

A control arrangement according to claim 32, wherein the differential which drives the main axle is a transverse differential having a pair of output shafts and adjustable power transmission characteristics, and wherein said arrangement further comprises: means on said transverse differential for receiving a control value and for adjusting the power transmission characteristics of the transverse differential in response thereto; means for determining a speed difference of the output shafts of the transverse differential; and means for producing said control value as a function of an exponential power of the speed difference of the output shafts and for supplying said control value to the means for adjusting the characteristics of the transverse differential.

Claim 36

A control arrangement according to claim 32, wherein the auxiliary axle is provided with a transverse differential having a pair of output shafts and adjustable power transmission characteristics, and wherein said arrangement further comprises: means on said transverse differential for receiving a control value and for adjusting the power transmission characteristics of the transverse differential in response thereto; means for determining a speed difference of the output shafts of the transverse differential; and means for producing said control value as a function of the speed difference of the output shafts and for supplying said control value to the means for adjusting the characteristics of the transverse differential.

Claim 37

A control arrangement according to claim 32, further comprising display means in a dashboard of the vehicle for displaying a current condition of the control arrangement.

Claim 38

A control arrangement according to claim 32, further comprising means for communicating with at least one digital computer system used in the vehicle for at least one of control, measuring, and data processing purposes.

Claim 39

A control arrangement according to claim 36, wherein said means for communicating with a digital computer system comprises a digital bus system.

Claim 40

A control arrangement according to claim 32, wherein said control arrangement is implemented at least partially in hardware technology.

Claim 41

A control arrangement according to claim 32, further comprising self-testing means for monitoring an operating condition of the control arrangement, and means for indicating an error condition.

Claim 42

A control arrangement according to claim 32, further comprising means for manually adjusting the power transmission characteristics of the coupling means independently of said control signal.

Claim 43

A control arrangement according to claim 32, wherein the first and the second differential are driven by a torque splitting gar box or differential with adjustable power transmission characteristics, and further comprising means on said additional gear box or differential for receiving said control signal and for adjusting the power transmission characteristics in response thereto.

Claim 44

A control arrangement for a four-wheel drive vehicle having a main axle provided with a first differential and having an auxiliary axle provided with a second differential, with the first differential driven directly and the second differential driven by coupling means having input and output shafts and adjustable power transmission characteristics, comprising: adjustment means on said coupling means for receiving a control signal and for adjusting the power transmission characteristics of the coupling in response thereto; means for determining a speed difference of the input and the output shafts of the coupling means; and means for producing said control signal as a function of the speed difference and for supplying said control signal to the adjustment means; wherein the control signal varies exponentially with the speed difference; and wherein said means for producing said control signal includes means for producing at least one intermediate control value as a function of a combination of an exponential power of the speed difference and a first control factor which is used to produce said control signal.

Claim 45

A control arrangement for a four-wheel drive vehicle having a main axle provided with a first differential and having an auxiliary axle provided with a second differential, with the first differential driven directly and the second differential driven by coupling means having input and output shafts and adjustable power transmission characteristics, comprising: adjustment means on said coupling means for receiving a control signal and for adjusting the power transmission characteristics of the coupling in response thereto; means for determining a speed difference of the input and the output shafts of the coupling means; and means for producing said control signal as a function of the speed difference and for supplying said control signal to the adjustment means; wherein the control signal varies exponentially with the speed difference; and wherein said means for producing said control signal includes means for producing at least one intermediate control value as a function of a combination of an exponential power of the speed difference and a first control factor which is used to produce said control signal.

Claim 46

A control arrangement according to claim 42, wherein said first control factor and said exponential power of the speed difference are combined by a multiplication operation.

Claim 47

A control arrangement according to claim 42, further comprising adjusting means for producing an adjusting control value, and means for combining said adjusting value and said intermediate control value to produce said control signal.

Claim 48

A control arrangement according to claim 44, wherein said combining means includes means for combining said adjusting and intermediate control values in a weighted sum relationship.

Claim 49

A control arrangement according to claim 44, wherein said combining means includes means for selecting a maximum value of said adjusting and intermediate control values.

Claim 50

A control arrangement according to claim 42, further comprising display means in a dashboard of the vehicle for displaying a current condition of the control arrangement.

Claim 51

A control arrangement according to claim 42, further comprising means for communicating with at least one digital computer system used in the vehicle for at least one of control, measuring, and data processing purposes.

Claim 52

A control arrangement according to claim 48, wherein said means for communicating with a digital computer system comprises a digital bus system.

Claim 53

A control arrangement according to claim 42, wherein said control arrangement is implemented at least partially in hardware technology.

Claim 54

A control arrangement according to claim 42, further comprising a self-testing means for monitoring an operating condition of the control arrangement, and means for indicating an error condition.

Claim 55

A control arrangement according to claim 42, further comprising means for manually adjusting the power transmission characteristics of the coupling means independentaly of said control signal.

Claim 56

A control arrangement according to claim 42, wherein the first and the second differential are driven by a torque splitting gear box or differential with adjustable power transmission characteristics, and further comprising means on said additional gear box or differential for receiving said control signal and for adjusting the power transmission characteristics in response thereto.

Claim 57

A control arrangement for a four-wheel drive vehicle having a main axle provided with a first differential and having an auxiliary axle provided with a second differential, with the first differential driven directly and the second differential driven by coupling means having input and output shafts and adjustable power transmission characteristics, comprising: adjustment means on said couplng means for receiving a control signal and for adjusting the power transmission characteristics of the coupling in response thereto; means for determining a speed difference of the input and the output shafts of the coupling means; and means for producing said control signal as a function of the speed difference and for supplying said control signal to the adjustment means; wherein the control signal varies exponentially with the speed difference; and wherein said four-wheel drive vehicle is equipped with an anti-locking braking system, and wherein said control arrangement includes means for receiving a signal from the anti-locking braking system during a braking operation, and said means for producing said control signal is reponsive to said signal from the anti-locking braking system.

Claim 58

A control arrangement for a four-wheel drive vehicle having a main axle provided with a first differential and having an auxiliary axle provided with a second differential, with the first differential driven directly and the second differential driven by coupling means having input and output shafts and adjustable power transmission characteristics, comprising: adjustment means on said couplng means for receiving a control signal and for adjusting the power transmission characteristics of the coupling in response thereto; means for determining a speed difference of the input and the output shafts of the coupling means; and means for producing said control signal as a function of the speed difference and for supplying said control signal to the adjustment means; wherein the control signal varies exponentially with the speed difference; and wherein said four-wheel drive vehicle is equipped with an anti-locking braking system, and wherein said control arrangement includes means for receiving a signal from the anti-locking braking system during a braking operation, and said means for producing said control signal is reponsive to said signal from the anti-locking braking system.

Claim 59

A control arrangement for a four-wheel drive vehicle having a main axle provided with a first differential and having an auxiliary axle provided with a second differential, with the first differential driven directly and the second differential driven by coupling means having input and output shafts and adjustable power transmission characteristics, comprising: adjustment means on said coupling means for receiving a control signal and for adjusting the power transmission characteristics of the coupling in response thereto; means for determining a vehicle driving speed; means for determining a desired power output; means for determining a magnitude of a desired traction force as a function of the vehicle driving speed and the desired power output; means for determining a vehicle driving resistance as a function of the vehicle driving speed; means for determining a magnitude of a traction force difference by subtracting the vehicle driving resistance from the magnitude of the desired traction force; means for determining a speed difference of the input and the output shafts of the coupling means; and means for producing said control signal as a function of the pulling force difference and the speed difference and for supplyng said control signal to said adjustment means.

Claim 60

A control arrangement for a four-wheel drive vehicle having a main axle provided with a first differential and having an auxiliary axle provided with a second differential, with the first differential driven directly and the second differential driven by coupling means having input and output shafts and adjustable power transmission characteristics, comprising: adjustment means on said coupling means for receiving a control signal and for adjusting the power transmission characteristics of the coupling in response thereto; means for determining a vehicle driving speed; means for determining a desired power output; means for determining a magnitude of a desired traction force as a function of the vehicle driving speed and the desired power output; means for determining a vehicle driving resistance as a function of the vehicle driving speed; means for determining a magnitude of a traction force difference by subtracting the vehicle driving resistance from the magnitude of the desired traction force; means for determining a speed difference of the input and the output shafts of the coupling means; and means for producing said control signal as a function of the pulling force difference and the speed difference and for supplyng said control signal to said adjustment means.

Claim 61

A control arrangement according to claim 55, wherein said first differential is a transverse differential having a pair of output shafts and adjustable power transmission characteristics, and wherein said arrangement further comprises: means on said first differential for receiving a first control value and for adjusting the power transmission characteristics of the first differential in response thereto; means for determining a speed difference of the output shafts of the first differential; and means for producing said first control value as a function of an exponential power of the speed difference of the output shafts and for supplying said first control value to the means for adjusting the characteristics of the first differential.

Claim 62

A control arrangement according to claim 56, wherein the auxiliary axle is provided with a transverse differential having a pair of output shafts and adjustable power transmission characteristics, and wherein said arrangement further comprises: means on said auxiliary axle differential for receiving a second control value and for adjusting the power transmission characteristics of the auxiliary axle differential in response thereto; means for determining a speed difference of the output shafts of the auxiliary axle differential; and means for producing said second control value as a function of an exponential power of the speed difference of the output shafts and for supplying said second control value to the means for adjusting the characteristics of the auxiliary axle differential.