Patent Application
20100228462
The present disclosure relates generally to engine controls and, more particularly, to a method and apparatus for determining engine brake torque.
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Engine brake torque is determined in various manners. Typically, an estimate of engine brake torque is created by collecting a large matrix of steady state engine operating points and regressing the measured engine brake torque against available engine operating variables, such as engine speed, mass airflow, spark and the like. Typically, the engine brake torque estimate is good to within plus or minus 15 Newton meters or about 10 percent. A more accurate determination of torque may allow a more precise control of the engine. More precise control of the engine may lead to increased power and increased fuel economy.
The present disclosure determines a torsional deflection of a friction clutch disk to provide a measurement of engine brake torque. This may be performed in real time to provide an accurate determination of engine torque that may later be used by the engine controller for controlling various engine functions.
In one aspect of the disclosure, a method includes generating a clutch deflection signal and controlling an engine function in response to the clutch deflection signal.
In a further aspect of the disclosure, a control module for controlling an engine function includes a deflection determination module generating a clutch deflection signal. The system further includes an engine function module controlling an engine function in response to the clutch deflection signal. The clutch deflection signal may be generated by sensors associated with the transmission shaft such as within the clutch housing or the friction disk.
In yet another aspect of the disclosure, a method includes generating a clutch spring force signal and controlling an engine function in response to the clutch spring force signal.
Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.
The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical or. It should be understood that steps within a method may be executed in different order without altering the principles of the present disclosure.
As used herein, the term module refers to an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.
Referring now to
The engine 12 may be various types of engines, including a diesel engine, a direct-injection engine, or the like.
The clutch 14 and transmission 20 are illustrated as separate components. The transmission 20 may be a manual transmission having a manually operated clutch with a clutch pedal and stick shift. The transmission 20 may also be automatic transmission and therefore clutch 14 may actually be incorporated within a transmission housing. A typical automatic transmission has several clutches to actuate various gears.
The driveline 24 may include a drive shaft, a differential and various other components.
The control module 26 may comprise one module or several modules combined together. The control module 26 may include the functions of an engine control module and a transmission control module if the transmission is an automatic transmission. As will be described below, the control module 26 may receive various signals for controlling the engine and the transmission. In particular, the present disclosure is directed to determining the engine brake torque which is the torque provided by the engine at the crankshaft 16. As will be described below, the engine brake torque may be determined using the torsional deflection of the friction disk of the clutch 14.
Referring now to
The clutch 14 illustrated in
The crankshaft 16 has a flywheel 46 coupled thereto. The transmission input shaft 22 has a clutch disk or clutch plate 48 coupled thereto. A pressure plate 50 is in communication with a diaphragm spring 52. When the clutch pedal is depressed, a cable or hydraulic piston pushes a piston or the like which is now shown which in turn pushes the diaphragm spring 52 toward the engine 12 and thus pushes the pressure place 50 to move the clutch disk 48 against the flywheel 46.
A clutch disk position sensor 60 may be positioned on the clutch housing 62. The clutch disk position sensor 60 may generate a clutch disk position signal corresponding to the deflection of the friction or clutch disk 48. The sensor 60 may be one of a number of different types of sensors, including a hall-effect sensor. The hall-effect sensor 60 may generate a signal from magnets, teeth, or the like positioned on the clutch disk 48.
Referring now to
A spring sensor 74 may be disposed to generate a spring-force signal or a spring deflection signal. The sensor 74 may be coupled directly to the spring and measure the force of force acting on the spring or a deflection of the spring. The spring deflection or the spring force sensed by the spring sensor 74 corresponds to the torsional deflection of the clutch and disk. The spring sensor 74 may be used instead of the sensor 60 illustrated in
Referring now to
A crankshaft position module 84 generates a crankshaft position signal corresponding to the crankshaft position measured or determined by the crankshaft position signal. The crankshaft position signal is communicated to the deflection determination module 82.
A deflection determination module 82 may compare the transmission shaft position signal and the crankshaft position signal. In one embodiment, the transmission shaft position signal may be subtracted from the crankshaft position module to determine an amount of torsional deflection of the clutch friction disk. The output of the deflection determination module may be provided to a torque determination module 84. The amount of torque or torsional deflection from the deflection signal provided by the deflection determination module 82 may correspond directly to a torque as determined in the torque determination module 84. The torque determined in the torque determination module 84 corresponds to the engine brake torque or the crankshaft torque. The engine brake torque determined in the torque determination module 84 may be communicated to the engine function module 86 using a torque signal. The engine function module 86 may be one of a variety of different types of engine functions using the engine brake torque.
A spring measurement module 90 may also be included in the control module. The spring measurement module 90 receives a spring deflection or spring force. The spring signal may be communicated to the deflection module 82 where an amount of spring deflection is determined based upon the spring signal. The spring measurement module 90 may also correspond to a spring force. The spring force may be converted to a deflection in the deflection module 82. The spring measurement module 90 may also generate a spring signal that corresponds to a spring force. The spring force may be converted directly to a torque in the torque determination module 84. As mentioned above, the spring measurement module 90 may be used instead of or in addition to the transmission shaft position modules 80 and the crankshaft position module 84.
Referring now to
Referring back to step 114, the clutch angular displacement may also be determined by a spring deflection signal. A spring deflection signal may be generated in step 140. This is an optional step or a replacement for steps 110 and 112. The spring deflection signal may generate a spring deflection corresponding to the deflection of the clutch disk in response to the torsion of the engine through the crankshaft. The clutch angular displacement may thus be determined in step 114 and the remainder of steps 116 and 118 may be performed.
Referring back to step 116, the engine brake torque is determined. The engine brake torque may be determined directly from a spring force signal. A spring force signal may be generated in step 150. Steps 150, 116 and 118 may thus be used to control an engine function. From the spring force generated in step 150, the engine brake torque may be determined. The brake torques in step 116 may be determined using a look-up table or through a calculated formula.
The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification, and the following claims.
