Electronic Transmission ControlThe case of electronically controlled trans-missions (ECT) is a typical example of power train system control, since it includes almost
all major aspects of vehicle longitudinal dy-namics, described in more detail in [ 7 ] , [8]. In addition to the engine dynamics, the ECT
example includes important dynamic effects
of torque converter and transmission elec-
trohydraulics. Moreover, unlike in the idle speed control case, the power train now can
operate at an almost arbitrary speed/load
point during the usually large transmission shift transients, which can amplify any non- linear effects present in the plant.
ECTs are employed to improve fuel econ-
omy, performance, and drivability, the latter being reflected through shift quality, for ex-
ample. Additional benefits include reduced
hardware complexity and packaging require- ments, creation of new functionality through coordination, creation of diagnostics, fault- detection capabilities and convenience/com-
munication centers, and as the display of
present gear information. Perhaps the great-
est potential benefit is the flexibility offered
by microcomputer software. An example of this can be found in current "adaptive" shift
schedules, which can be tailored for im- proved fuel economy, performance, or com- fort. Potential disadvantages are (at least ini- tially) in the issues of electronic reliability,
software complexity, and cost.
In general, ECTs are characterized by the fact that many hydraulic functions of con-
ventional automatic transmissions are re-
placed by electronic and electrohydraulic
counterparts. Listed below, in an approxi-
mate order of increased complexity, are some
of the possible electronically controlled
functions and their typical implementations:
Torque converter lockup (open loop; on/
off solenoids). The lockup is used to re-
ducc torque converter losses and, thus, improve the fuel economy, particularly
while driving in higher gears.
Lubeiclutch cooling (onioff solenoids).
Cooling is typically used during the shifts.
When-to-shift or shift scheduling [onioff
solenoids, variable force solenoid (VFS), or pulse width modulation (PWM) sole- noids for throttle valve control; rpm sen- sors].
Torque converter bypass clutch slip con-
trol (closed loop).
Neutral idle (strategies for smooth transi-
tion fromito neutral idle).
Speed ratio (SR) control for continuously
variable transmissions (CVTs) (closed
loop; PWM or VFS).
Line pressure control (open or closed loop;
PWM or VFS). The line pressure serves
as the main source of actuation for auto-
matic-transmission hydraulic systems.
CVT belt load control (open or closed
loop; PWM or VFS).
Drive-away or driving from stop for ECTs
without torque converters (open or closed
loop; PWM or VFS; possibly augmented
by drive-by-wire throttle control).
How-to-shift or shift execution (open or
closed loop; PWM or VFS; possibly aug- mented by spark, fuel, and drive-by-wire
throttle control).
As with conventional automatics, ECTs
can be divided into two major groups: dis-
crete and CVTs. The work on electronically controlled CVTs is an ongoing research ac-
tivity in a numbcr of automotive and related
companies. Many of the control principles used for discrete ratio ECTs can be used for CVTs as well. While the discrete ratio ECTs
are characterized by many large transients of short duration (shifts), the CVT control is more of a continuous ("process control")
nature, and, as such, it typically results in
simpler software.
Discrete ECTs can be classified according
to whether only the shift scheduling phase is
done electronically or whether both the shift
scheduling ("when-to") and shift execution
("how-to") are implemented via electron-
ics. Moreover, the shift execution can be im-
plemented by either open- or closed-loop ap-
proachcs. The main emphasis in the
following example will be on discrete ratio
ECTs. where both shift scheduling and ex-
ecution are implemented under computer control, with the shift execution under
closed-loop control.
The schcmatic of an example prototype
four-speed transaxle ECT is shown in Fig.
7 . The example illustrates some basic shift
control principles applicable to many dis-
crete ratio ECTs. The transmission consists
of a torque converter; reverse, low, and high
clutches; and a single shift actuator-a so-
called "dog actuator." The low clutch is
constantly engaged in the first gear and the
high clutch is constantly engaged in the
fourth gear. The dog actuator is used to en- gage the second gear when displaced to the left in Fig. 7, or the third gear when dis-
placed to the right. Finally, the power is
transmitted to the front wheels through the differential and CV-joint-equipped axles.
อิเล็กทรอนิกส์ส่ง ControlThe ควบคุมด้วยอิเล็กทรอนิกส์ทรานส์ภารกิจ (ECT) เป็นตัวอย่างทั่วไปของรถยนต์ระบบควบคุม ตั้งแต่มันรวมถึงเกือบ ประเด็นสำคัญทั้งหมดของรถยาว dy-namics อธิบายรายละเอียดเพิ่มเติมใน [7], [8] นอกจากโปรแกรม dynamics, ECT ตัวอย่างที่มีลักษณะพิเศษแบบไดนามิกที่สำคัญ แรงบิดและส่งไฟฟ้าหนึ่ง- trohydraulics นอกจากนี้ ซึ่งแตกต่างจากในกรณีควบคุมความเร็วในการใช้งาน รถยนต์ตอนนี้สามารถ ทำงานที่มีความเร็ว/โหลดโปรแกรมเกือบ จุดในระหว่างการส่งข้อมูลขนาดใหญ่มักจะกะทรานเซี้ยนต์ ซึ่งสามารถขยายผลใด ๆ ที่ไม่เชิงเส้นในโรงงาน ECTs จะจ้างเพื่อปรับปรุงน้ำมันชโรด- ชนะไิน ประสิทธิภาพ และ drivability หลังสะท้อนผ่านกะคุณภาพ เก่า กว้างขวาง เพิ่มเติมสิทธิประโยชน์ลดลง ความซับซ้อนของฮาร์ดแวร์ และบรรจุภัณฑ์ต้องการยืน การสร้างฟังก์ชันใหม่ผ่านการประสานงาน วินิจฉัย ประสิทธิภาพการตรวจจับข้อบกพร่อง และความสะดวก สบาย/com- ศูนย์ munication และ เป็นการแสดง ข้อมูลปัจจุบันเกียร์ บางทีดี- เอสเกิดประโยชน์เป็นความยืดหยุ่นที่เสนอ ซอฟต์แวร์ไมโครคอมพิวเตอร์ ตัวอย่างนี้สามารถพบได้ในปัจจุบันกะ "ปรับตัว" ตาราง ซึ่งสามารถปรับแต่งสำหรับ im-พิสูจน์แล้วว่าประหยัดเชื้อเพลิง ประสิทธิภาพ หรือ ป้อม com มีข้อเสียที่อาจเกิดขึ้น (น้อย ini - tially) ในเรื่องของความน่าเชื่อถือทางอิเล็กทรอนิกส์ software complexity, and cost. In general, ECTs are characterized by the fact that many hydraulic functions of con- ventional automatic transmissions are re- placed by electronic and electrohydraulic counterparts. Listed below, in an approxi- mate order of increased complexity, are some of the possible electronically controlled functions and their typical implementations: Torque converter lockup (open loop; on/ off solenoids). The lockup is used to re- ducc torque converter losses and, thus, improve the fuel economy, particularly while driving in higher gears. Lubeiclutch cooling (onioff solenoids). Cooling is typically used during the shifts. When-to-shift or shift scheduling [onioff solenoids, variable force solenoid (VFS), or pulse width modulation (PWM) sole- noids for throttle valve control; rpm sen- sors]. Torque converter bypass clutch slip con- trol (closed loop). Neutral idle (strategies for smooth transi- tion fromito neutral idle). Speed ratio (SR) control for continuously variable transmissions (CVTs) (closed loop; PWM or VFS). Line pressure control (open or closed loop; PWM or VFS). The line pressure serves as the main source of actuation for auto- matic-transmission hydraulic systems. CVT belt load control (open or closed loop; PWM or VFS). Drive-away or driving from stop for ECTs without torque converters (open or closed loop; PWM or VFS; possibly augmented by drive-by-wire throttle control). How-to-shift or shift execution (open or closed loop; PWM or VFS; possibly aug- mented by spark, fuel, and drive-by-wire throttle control). As with conventional automatics, ECTs can be divided into two major groups: dis- crete and CVTs. The work on electronically controlled CVTs is an ongoing research ac- tivity in a numbcr of automotive and related companies. Many of the control principles used for discrete ratio ECTs can be used for CVTs as well. While the discrete ratio ECTs are characterized by many large transients of short duration (shifts), the CVT control is more of a continuous ("process control") nature, and, as such, it typically results in simpler software. Discrete ECTs can be classified according to whether only the shift scheduling phase is done electronically or whether both the shift scheduling ("when-to") and shift execution ("how-to") are implemented via electron- ics. Moreover, the shift execution can be im- plemented by either open- or closed-loop ap- proachcs. The main emphasis in the following example will be on discrete ratio ECTs. where both shift scheduling and ex-ecution are implemented under computer control, with the shift execution under closed-loop control. The schcmatic of an example prototype four-speed transaxle ECT is shown in Fig. 7 . The example illustrates some basic shift control principles applicable to many dis- crete ratio ECTs. The transmission consists of a torque converter; reverse, low, and high clutches; and a single shift actuator-a so- called "dog actuator." The low clutch is constantly engaged in the first gear and the high clutch is constantly engaged in the fourth gear. The dog actuator is used to en- gage the second gear when displaced to the left in Fig. 7, or the third gear when dis- placed to the right. Finally, the power is transmitted to the front wheels through the differential and CV-joint-equipped axles.
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