US 7,234,366 B2Granted

Power take-off control system

AssigneeCNH America LLC

InventorYanming Hou

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Abstract

A control system and method for detecting variable load types and controlling the operation of a PTO clutch to effect engagement of the clutch with variable loads, and especially to more optimally effect the engagement of a clutch with a very light load or an associated over-running clutch is disclosed. The control system includes a controller that receives input and output clutch shaft speed signals and generates control signals to control the pressure applied by the clutch. If no appreciable engine droop is detected at the time of initial movement of the output clutch shaft, the load is considered to be of a very light load type, and a set of control signals based upon such load type designation, which control signals define a control curve that is flatter and more gentle than would otherwise be considered desirable, is thereafter applied to the clutch to effect engagement of the load.

Claims24

Dependent claims

In a vehicle having a power source for producing rotational motion, a power take-off shaft for supplying rotational motion to at least one piece of equipment other than the vehicle, and a clutch including an input shaft coupled to the power source and an output shaft coupled to the PTO shaft, wherein the clutch transmits a maximum torque between the input and output shafts in response to a maximum clutch pressure and transmits a selectable torque between the input and output shafts in response to a selected clutch engagement pressure less than the maximum clutch engagement pressure, a power take-off control system comprising:

a first transducer disposed to generate an input shaft speed signal representative of the rotational speed of the input shaft;
a second transducer disposed to generate an output shaft speed signal representative of the rotational speed of the output shaft;
a clutch control configured to effect engagement and disengagement by the clutch in response to engagement control signals applied thereto, the clutch transmitting a selectable torque between the input and output shafts dependent upon a clutch engagement pressure defined by said engagement control signals, wherein the clutch engagement pressure is variable up to the maximum engagement pressure;
a controller coupled to the clutch control, the first transducer, and the second transducer, said controller operable to monitor the input shaft speed signals and the output shaft speed signals generated by said first and second transducers and to produce time-based engagement control signals dependent thereon,
said engagement control signals each including a characteristic representative of an associated amount of clutch pressure to be applied,
said controller operable to generate a first set of time-based engagement control signals during a time period between commencement of an engagement operation and the time at which an output shaft speed signal indicative of movement by the output shaft is detected by said controller, and a second set of engagement signals at times subsequent to said detection of movement by the output shaft,
said controller operable, upon detection of movement of the output shaft, to determine whether the monitored input speed at such time has remained within an established deviation value from the nominal input speed prior to such time and to establish a first load status if the speed has remained within the established deviation value and to establish another load status if the speed has not remained within the established deviation value,
said second set of time-based engagement signals including a subset of engagement control signals dependent, in part, upon the established load status and defining a flattened control curve relative to control curves that are established for loads of said another load status.

5 more elements

A method for engaging and operating variable loads on a power take-off shaft in a system having

a power source for producing rotational motion;
a power take-off shaft for supplying rotational motion to at least one piece of equipment coupled to the power take-off shaft;
a clutch including an input shaft coupled to the power source and an output shaft coupled to the PTO shaft, wherein the clutch transmits a maximum torque between the input and output shafts in response to a maximum clutch pressure and transmits a selectable torque between the input and output shafts in response to a given clutch engagement pressure less than the maximum clutch engagement pressure;
a first transducer disposed to generate an input shaft speed signal representative of the rotational speed of the input shaft;
a second transducer disposed to generate an output shaft speed signal representative of the rotational speed of the output shaft;
a clutch control configured to effect engagement and disengagement by the clutch in response to engagement control signals applied thereto, the clutch transmitting a selectable torque between the input and output shafts dependent upon a given clutch engagement pressure defined by said engagement control signals, wherein the clutch engagement pressure is variable up to the maximum engagement pressure;
a controller coupled to the clutch control, the first transducer, and the second transducer, said controller operable to monitor the input shaft speed signals and the output shaft speed signals generated by said first and second transducers, and to produce time-based engagement control signals dependent thereon,
the engagement control signals each including a characteristic representative of an associated amount of clutch pressure to be applied;
and
the controller operable to generate a first set of time-based engagement control signals during a time period between commencement of an engagement operation and the time at which an output shaft speed signal indicative of movement by the output shaft is detected by said controller, and a second set of engagement signals at times subsequent to said detection of movement by the output shaft;
the method comprising:
(a) monitoring the output shaft speed signals to detect the speeds at given times of the output shaft and initial movement of the output shaft as a result of application of engagement control signals;
(b) monitoring the input shaft speed signals to detect the speeds at given times of the input shaft;
(c) determining, upon detection of initial movement of the output shaft, the deviation of speed of the input shaft and establishing a first load status if the speed deviation has remained within an established deviation value and establishing another load status if the speed has not remained within the established deviation value;
(d) applying, for said first load status, a set of time-based engagement control signals defining a flattened control relative to control curves that would be applied for loads of said another load status.

12 more elements

A method for engaging variable loads on a power take-off shaft in a system having

a power source for producing rotational motion;
a power take-off shaft for supplying rotational motion to at least one piece of equipment coupled to the power take-off shaft;
a clutch including an input shaft coupled to the power source and an output shaft coupled to the PTO shaft, wherein the clutch transmits a maximum torque between the input and output shafts in response to a maximum clutch pressure and transmits a selectable torque between the input and output shafts in response to a given clutch engagement pressure less than the maximum clutch engagement pressure;
a first transducer disposed to generate an input shaft speed signal representative of the rotational speed of the input shaft;
a second transducer disposed to generate an output shaft speed signal representative of the rotational speed of the output shaft;
a clutch control configured to effect engagement and disengagement by the clutch in response to engagement control signals applied thereto, the clutch transmitting a selectable torque between the input and output shafts dependent upon a given clutch engagement pressure defined by said engagement control signals, wherein the clutch engagement pressure is variable up to the maximum engagement pressure;
a controller coupled to the clutch control, the first transducer, and the second transducer, said controller operable to monitor the input shaft speed signals and the output shaft speed signals generated by said first and second transducers, and to produce time-based engagement control signals dependent thereon,
the engagement control signals each including a characteristic representative of an associated amount of clutch pressure to be applied;
and
the controller operable to generate a first set of time-based engagement control signals during a time period between commencement of an engagement operation and the time at which an output shaft speed signal indicative of movement by the output shaft is detected by said controller, and a second set of engagement signals at times subsequent to said detection of movement by the output shaft;
the method comprising:
(a) monitoring the input and output shaft speed signals to detect the speeds at given times of the input and output shafts;
(b) periodically checking to determine if output shaft movement has occurred;
(c) upon detection of initial output shaft movement, checking to determine whether the monitored input speed at such time has remained within an established deviation value from the nominal input speed prior to such time and,
(1) if the input speed has remained within the established deviation value, establishing a first load status and then proceeding to step (d);
or
(2) if the input speed has not remained within the established deviation value, establishing another load status and then proceeding to step (d);
(d) applying a set of time-based engagement control signals, dependent in part upon the established load status, to the clutch;
whereby a set of time-based engagement control signals for the first load status define a flattened control curve relative to control curves that would be applied for loads of said another load status.

16 more elements

Dependencies are inferred from the claim text.