Method of and apparatus for transmitting torque in vehicular power trains
First Claim
1. A method of operating a torque transmitting apparatus which receives torque from a rotary output element of a prime mover and transmits torque to a rotary input element of an automatic transmission in a power train of a vehicle, wherein the torque transmitting apparatus comprises a hydrokinetic torque converter and a slip clutch arranged in parallel to transmit torque between the output and input elements and wherein the amount of torque being transmitted by the clutch is controlled by a computerized regulating unit, the method comprising the steps of:
- regulating the amount of torque to be transmitted by the clutch as a function of the magnitude of torque being transmitted by the output element of the prime mover;
calculating what amount of force will have to be applied to the clutch, so that the clutch will transmit said predetermined amount of torque, wherein the amount of torque is determined and the amount of force is calculated so that the clutch operates with a desired minimum amount of slip, andcarrying out a compensation for long-term departures of the torque actually transmitted by the clutch from the predetermined torque.
1 Assignment
0 Petitions
Accused Products
Abstract
The magnitude of torque which can be transmitted by a bypass clutch between the housing and the turbine of a torque converter between a prime mover, such as an engine, and an automatic transmission in the power train of a motor vehicle is selectively regulatable by a computerized regulating unit. The regulation involves the transmission of torque by the clutch in dependency upon the magnitude of the torque being transmitted by the output element of the engine and ascertaining as well as adaptively applying to the clutch a variable force so that the clutch can transmit a predetermined torque. This entails automatic selection of a minimum slip between a torque receiving and a torque transmitting part of the power train. Compensation, particularly long-range compensation, is carried out for the existence of possible differences between the predetermined and actual torques being transmitted by the clutch.
77 Citations
39 Claims
-
1. A method of operating a torque transmitting apparatus which receives torque from a rotary output element of a prime mover and transmits torque to a rotary input element of an automatic transmission in a power train of a vehicle, wherein the torque transmitting apparatus comprises a hydrokinetic torque converter and a slip clutch arranged in parallel to transmit torque between the output and input elements and wherein the amount of torque being transmitted by the clutch is controlled by a computerized regulating unit, the method comprising the steps of:
-
regulating the amount of torque to be transmitted by the clutch as a function of the magnitude of torque being transmitted by the output element of the prime mover; calculating what amount of force will have to be applied to the clutch, so that the clutch will transmit said predetermined amount of torque, wherein the amount of torque is determined and the amount of force is calculated so that the clutch operates with a desired minimum amount of slip, and carrying out a compensation for long-term departures of the torque actually transmitted by the clutch from the predetermined torque. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
-
-
25. A method of operating a torque transmitting apparatus which receives torque from a rotary output element of a prime mover and transmits torque to a rotary input element of an automatic transmission in a power train of a vehicle, wherein a hydrokinetic torque converter is arranged to transmit torque between the output and input elements in parallel with a slip clutch, wherein the magnitude of torque being transmitted by the clutch is detectable by a monitoring unit in conjunction with a central computer unit, and wherein the application of force to, and hence the magnitude of torque being transmitted by, the clutch is controllable by the computer unit, comprising the steps of:
-
ascertaining the magnitude of torque to be transmitted by the clutch in dependency upon the operating condition of the power train in accordance with the equation
Mclutch=ke·
kcorr·
Mpm, whereinke=kme is a torque dividing factor for apportioning respective amounts of torque being transmitted by the slip clutch and the torque converter, Kcorr is a correction factor that is dependent on a current operating point of the power train, Mclutch is the torque being transmitted by the clutch and Mpm is the torque being transmitted by the rotary output element of the prime mover, (b) ascertaining the magnitude of the force to be applied to the clutch for the transmission of a predetermined torque, and (c) applying the thus ascertained force to the clutch, wherein the slip between the output and input elements adjusts itself automatically as a function of the torque dividing factor ke and possible deviations of an individual power train from an ideal behavior are corrected by the correction factor kcorr.
-
-
26. A method of operating a torque transmitting apparatus which receives torque from a rotary output element of a prime mover and transmits torque to a rotary input element of an automatic transmission, wherein a hydrokinetic torque converter is arranged to transmit torque between the output and input elements in parallel with a slip clutch and wherein the magnitude of torque being transmitted by the clutch is detectable by a monitoring device in conjunction with a central computer unit, comprising the steps of:
-
(a) ascertaining the magnitude of torque to be transmitted by the clutch in dependency upon the operating condition of the power train in accordance with the equation
Mclutch=ke·
kcorr·
Mpm, whereinke=Kme is a torque dividing factor which is independent of a characteristic field of the prime mover, kcorr is a correction factor that is dependent on a current operating point of the power train, and Mpm is the torque being transmitted by the prime mover, (b) ascertaining the magnitude of the force to be applied to the clutch for the transmission of a predetermined torque, and (c) applying the thus ascertained force to the clutch, wherein the slip between the output and input elements adjusts itself automatically as a function of the torque dividing factor ke and possible deviations of an individual power train from an ideal behavior are corrected by the correction factor kcorr.
-
-
27. A method of operating a torque transmitting apparatus which receives torque from a rotary output element of a prime mover and transmits torque to a rotary input element of an automatic transmission, wherein a hydrokinetic torque converter is arranged to transmit torque between the output and input elements in parallel with a slip clutch and wherein the magnitude of torque being transmitted by the clutch is detectable by a monitoring device in conjunction with a central computer unit, comprising the steps of
(a) ascertaining the magnitude of torque Mclutch to be transmitted by the clutch in dependency upon the operating condition of the torque transmitting apparatus in accordance with the equation
Mclutch=ke·- kcorr·
Mpm, wherein ke=kmeke=kme is a torque dividing factor which is dependent only upon the RPM of the output element of the prime mover, kcorr is a correction factor that is dependent on a current operating point of the power train, and Mpm is the torque being transmitted by the prime mover, (b) ascertaining the magnitude of the force to be applied to the clutch for the transmission of a predetermined torque, and (c) applying the thus ascertained force to the clutch, wherein the slip between the output and input elements adjusts itself automatically as a function of the torque dividing factor ke and possible deviations of an individual power train from an ideal behavior are corrected by the correction factor kcorr.
- kcorr·
-
28. A method of operating a torque transmitting apparatus which receives torque from a rotary output element of a prime mover and transmits torque to a rotary input element of an automatic transmission, wherein a hydrokinetic torque converter is arranged to transmit torque between the output and input elements in parallel with a slip clutch and wherein the magnitude of torque being transmitted by the clutch is detectable by a monitoring device in conjunction with a central computer unit, comprising the steps of
(a) ascertaining the magnitude of torque Mclutch to be transmitted by the clutch in dependency upon the operating condition of the torque transmitting apparatus in accordance with the equation
Mclutch=ke·- kcorr·
Mpm, wherein ke=kmeke=kme is a torque dividing factor which is dependent only upon the RPM of the output element of the prime mover and the magnitude of torque being transmitted by the output element of the prime mover, kcorr is a correction factor that is dependent on a current operating point of the power train, and Mpm is the torque being transmitted by the prime mover, (b) ascertaining the magnitude of the force to be applied to the clutch for the transmission of a predetermined torque, and (c) applying the thus ascertained force to the clutch, wherein the slip between the output and input elements adjusts itself automatically as a function of the torque dividing factor ke and possible deviations of an individual power train from an ideal behavior are corrected by the correction factor kcorr.
- kcorr·
-
29. A method of operating a torque transmitting apparatus which receives torque from a rotary output element of a prime mover and transmits torque to a rotary input element of an automatic transmission in a power train of a vehicle, wherein a hydrokinetic torque converter is arranged to transmit torque between the output and input elements in parallel with a slip clutch, and wherein the magnitude of torque being transmitted by the clutch is variable by a pressure differential between two bodies of a hydraulic fluid one of which is confined in a first compartment between a housing of the torque converter and the slip clutch and the other of which is confined in a separate second compartment between the housing and the clutch, and wherein the pressure differential is detectable by a monitoring unit in conjunction with a central computer unit and, and wherein the application of force to, and hence the magnitude of torque being transmitted by, the clutch is controllable by the computer unit, comprising the steps of
(A) determining the RPM of said output element, (B) ascertaining the magnitude of torque to be transmitted by the clutch in dependency upon the operating condition of the power train in accordance with the equation Mclutch=ke· - kcorr·
Mpm, wherein ke=kme is a torque dividing factor which satisfies at least one of the requirements including (a) at least substantial constancy within the entire operating range of the power train, (b) independence from a characteristic field of the prime mover, (c) dependency exclusively upon the RPM of the output element of the prime mover, and (d) dependency upon the RPM of the prime mover and the magnitude of torque being transmitted by the output element, kcorr is a correction factor, Mclutch is the torque being transmitted by the clutch and Mpm is the torque being transmitted by the rotary output element of the prime mover,(C) ascertaining the magnitude of the force to be applied to the clutch for the transmission of a predetermined torque, and (D) applying the thus ascertained force to the clutch, wherein the slip between the output and input elements adjusts itself automatically as a function of the torque dividing factor ke and possible deviations of an individual power train from an ideal behavior are corrected by the correction factor kcorr ascertaining the magnitude of the force to be applied to the clutch for the transmission of a predetermined torque, and applying the thus ascertained force to the clutch with attendant automatic selection of the slip between the output and input elements as a function of the torque dividing factor ke and compensation for eventual departures from the desired torque transmission, as a function of the correction factor kcorr, due to the characteristics of the selected power train. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
(D) repeating the steps (A), (B) and (C) until the parameter X at least closely approximates the desired parameter.
- kcorr·
-
34. The method of claim 29, wherein further in response to changes of the torque being transmitted by the power train a new torque is to be transmitted by the clutch is implemented through the following measures:
-
(A) determining a gradient Δ
X of a parameter X which determines the torque being transmitted by the clutch in accordance with a function that excludes undesirable phenomena including at least a short-lasting blocking of the clutch,(B) applying the gradient Δ
X with a hydraulic system, wherein a gradient Δ
Δ
P of a pressure differential Δ
P between two bodies of a hydraulic fluid at opposite sides of a pressure plate of the clutch in a housing of the torque converter is arrived at in accordance with the equation Δ
Δ
P=C1·
(Δ
Pdesird−
Δ
Pn), wherein C1 is a proportionality factor, and(C) repeating the steps (A) and (B) until the parameter X at least approximates a desired value.
-
-
35. The method of claim 29, wherein when a reduction of torque being transmitted by the apparatus can be predicted as a result of at least one of a plurality of occurrences including shifting of the transmission into a different drive ratio and attachment of at least one aggregate to an output element of the transmission and said predicted reduction of torque can cause short-lasting blockage of the clutch, the method further comprising the step of reducing the magnitude of torque being transmitted by the clutch by reducing the factor ke by a predetermined value, and thereupon gradually increasing each reduced factor as a function of time to a level where the amount of the torque being transmitted by the clutch is compatible with adequate insulation of the transmission from vibrations and economical fuel consumption by the prime mover.
-
36. The method of claim 29, wherein when a reduction of torque being transmitted by the apparatus can be predicted as a result of at least one of a plurality of occurrences including shifting of the transmission into a different drive ratio and attachment of at least one aggregate to an output element of the transmission and said predicted reduction of torque can cause short-lasting blockage of the clutch, the method further comprises the step of reducing the magnitude of torque being transmitted by the clutch through at least one of the following measures:
- (A) reducing the factor ke by a predetermined value, and (B) reducing the factor kcorr by a predetermined value and thereupon increasing each reduced factor as a function of time to a level where the amount of the torque being transmitted by the clutch is compatible with adequate insulation of the transmission from vibrations and economical fuel consumption by the prime mover.
-
37. The method of claim 29, wherein the factor Kcorr is indicative of a power train of a specific vehicle, and wherein the steps for selecting the factor kcorr to compensate for deviations of the characteristics of said power train of the specific vehicle from desired characteristics include:
-
(a) monitoring the slip of the clutch in a predetermined substantially stationary range of operation of the apparatus with a time delay which is sufficient to prevent the transmission of fluctuations of transmitted torque, (c) comparing the monitored slip with a reference value which is selected to ensure optimal insulation of the transmission from vibrations and economical fuel consumption by the prime mover, and (d) altering the slip of the clutch when the monitored slip departs from the reference value.
-
-
38. The method of claim 29, further comprising the steps of (a) detecting an impending acceleration of the prime mover based on a throttle valve position, and (b) if an impending acceleration is detected, reducing at least one of the factors ke and kcorr so that the slip of the clutch increases and the torque boost offered by the torque converter is available as an additional torque reserve.
-
39. The method of claim 29, wherein the transmission has a plurality of drive ratios and the torque-transmitting apparatus has a combined slip0 resulting from the slip of the clutch and from a less than perfect torque-transmitting efficiency of the torque converter, and wherein at each of said drive ratios said combined slip is determined primarily by the slip of the clutch, so that the efficiency of the torque converter becomes a less important factor for transmission of torque from the rotary output element to the rotary input element so that the torque converter can be designed for a wide torque conversion range.
Specification