Throttle control for automated mechanical transmission

An improved throttle control assembly (36) in combination with an electronic controller (48) for controlling shifting in an automated mechanical transmission system (10) having a non-electronically controlled engine (14) is provided. The combination of the throttle control assembly and the control allows the non-electronically controlled engine to be subject to throttle blip as well as throttle dip operations while preventing continuing unsafe conditions as a result of single point failures.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to controls for controlling engine fueling in 
a vehicular automated mechanical transmission system. In particular, the 
present invention relates to controls for automatically controlling the 
fueling of non-electronically controlled engines in automated mechanical 
transmission systems during both upshifting and downshifting, which 
provides improved shift quality, and which will not cause unintended full 
fueling of the engine with the driveline engaged as the result of a single 
point failure arid will quickly respond to certain multiple point failures 
leading to undesired increased engine fueling by returning fuel control to 
the vehicle operator. 
2. Description of the Prior Art 
Automated mechanical transmission systems and controls therefor are known 
in the prior art, as may be seen by reference to U.S. Pat. Nos. 4,361,060; 
4,595,986; 4,614,126; 4,648,290; 5,063,511; 5,109,729; 5,117,791 and 
5,335,566, the disclosures of which are incorporated herein by reference. 
In automated mechanical transmission systems equipped with electronically 
controlled engines (i.e., engines having dedicated microprocessor 
controllers and communicating with a data bus, such as the data buses 
conforming to the SAE J-1922 or SAE J-1939 protocols), engine fueling 
during both upshift and downshift transients typically is controlled by a 
system controller which causes fuel "dip" (Le., decreased fueling) or fuel 
"blip" (Le., increased fueling), as required, regardless of the operators 
positioning of the throttle pedal. 
In systems with electronically controlled engines, the driver's throttle 
position is one of multiple inputs to a controller, which issues command 
output signals to various actuators, including the engine fuel controller 
(see, for example, U.S. Pat. No. 5,425,284, the disclosure of which is 
incorporated herein by reference). The controller usually communicates 
with the engine fuel control over an electronic data link or data bus of 
the type conforming to a standardized protocol such as SAE J-1922, SAE 
J-1939 or ISO 11898. In systems with non-electronically controlled 
engines, the operator's throttle setting is a direct input to the engine 
fuel controller, which input may be interrupted or modified by various 
devices. 
In vehicles not equipped with electronically controlled engines, automatic 
throttle dip was used to break torque across engaged jaw clutches for 
shifting into neutral and to synchronize for upshifts. However, automatic 
throttle blip was not used during downshift transients to prevent the 
possible occurrence of a single point failure resulting in the dangerous 
condition of continuous unintended increased fueling of the engine, 
especially in conditions of an engaged drivetrain (i.e., master clutch 
engaged and transmission not in neutral). Such systems typically required 
manual synchronizing (i.e., increased engine and input shaft speeds) for 
downshifts and/or used power synchronizer devices (see aforementioned U.S. 
Pat. Nos. 4,614,126 and 5,063,511) and/or required elaborate redundant 
safety features. 
The prior art automated mechanical transmission systems not utilizing 
electronically controlled engines were subject to improvement in the areas 
of control complexity and/or shift rapidity and quality. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, the drawbacks of the prior art 
are minimized or overcome by the provision of a relatively simple and 
inexpensive throttle control mechanism which, in combination with an 
automated mechanical transmission system control, allows automatic control 
of engine fueling for both upshifts (throttle dip) and downshifts 
(throttle blip) in systems not utilizing electronically controlled 
engines, while maintaining protection against single point failures 
causing continued, potentially dangerous conditions. Accordingly, it is an 
object of the present invention to provide a new and improved throttle 
control mechanism and automated mechanical transmission system control for 
transmission systems having nonelectronically controlled engines. 
This and other objects and advantages of the present invention will become 
apparent from a reading of the detailed description of the preferred 
embodiment taken in connection with the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 schematically illustrates a vehicular automated mechanical 
transmission system 10 including an automated, multiple-speed, changegear 
transmission 12 driven by a non-electronically controlled, fuel-controlled 
engine 14, such as a well-known diesel engine, through a non-positive 
coupling such as a master friction clutch or torque converter disconnect 
clutch 16. The output of the automated transmission 12 is output shaft 18, 
which is adapted for driving connection to an appropriate vehicle 
component, such as the differential of a drive axle, a transfer case or 
the like, as is well known in the prior art. 
The crank shaft 20 of engine 14 will drive the driving plates 22 of the 
friction clutch 16, which are frictionally engageable to the driven plates 
24 for driving the input shaft 26 of the transmission 12. An upshift or 
inertia brake 28 may be provided for slowing the rotational speed of the 
input shaft and the transmission components driven thereby for more rapid 
upshifting. 
While Fig. I illustrates the clutch 16 as a master friction clutch, clutch 
10 may be a torque converter disconnect or interrupt clutch of the type 
illustrated in aforementioned U.S. Pat. No. 4,784,019. 
The aforementioned power train components are acted upon, monitored by 
and/or controlled by several devices, each of which will be discussed 
briefly below. These devices include a throttle pedal position or throttle 
opening monitor assembly 30, which senses the operator-set position of the 
operator-controlled throttle pedal 32 and may provide an output signal 
indicative thereof, and a shift control monitor assembly 34 by which the 
operator may select a reverse (R), a neutral (N), a forward drive (D) or a 
low (L) mode of operation of the vehicle. The devices also may include a 
throttle control assembly 36 for controlling the amount of fuel to be 
supplied to the engine 14, an engine speed sensor 38 for providing an 
input signal (ES) indicative of the rotational speed of the engine, a 
clutch operator 40 which engages and disengages the friction clutch 16 and 
which also may provide information as to the status of the clutch, an 
input shaft speed sensor 42 for sensing the rotational speed of the 
transmission input shaft 26 and for providing an input signal (IS) 
indicative thereof, a transmission operator 44 effective to shift the 
transmission 12 into a selected gear ratio and to provide a signal 
indicative of the gear neutral position and/or the currently engaged gear 
ratio of the transmission, and an output shaft speed sensor 46 for sensing 
the rotational speed of the transmission output shaft 18 and for providing 
a signal (OS) indicative thereof. 
Drive components and controls therefor of the type described above are 
known in the prior art and may be appreciated in greater detail by 
reference to U.S. Pat. Nos. 4,959,986; 4,576,065 and 4,445,393, the 
disclosures of which are incorporated herein by reference. The sensors may 
be of any known type of construction for generating analog and/or digital 
signals proportional to the parameter monitored thereby. Similarly, the 
operators may be of any known electric, hydraulic, pneumatic or 
combination type for executing operations in response to command output 
signals. 
The aforementioned devices supply information to and/or accept command 
output signals from a central processing unit or controller 48. The 
central processing unit 48 may include analog and/or digital electronic 
calculation and logic circuitry, as is well known in the prior art. An 
electric power source (not shown) and/or a source of pressurized fluid 
(not shown) provides electrical and/or fluid power to the various sensing 
and/or operating and/or processing units. As is well known, and as 
disclosed in aforementioned U.S. Pat. No. 4,595,986, central processing 
unit 48 is preferably microprocessor-based and is adapted to receive 
various input signals 50 from the sensors and to process same according to 
predetermined logic rules to issue command output signals 52 to the 
appropriate system actuators. 
In automated mechanical transmission systems of the type illustrated in 
FIG. 1, synchronization of the jaw clutch members associated with 
engagement of a target gear ratio (GR.sub.T) is normally accomplished, 
after a shift into transmission neutral, by increasing or decreasing the 
input shaft speed to cause the input shaft to rotate at a rotational speed 
generally equal to the product of the output shaft speed multiplied by the 
numerical ratio of the target gear ratio (IS=OS.times.GR.sub.T). For 
downshifts, where input shaft speed must generally be increased, increased 
fueling of the engine 14 with the master clutch 16 fully engaged will 
provide the desired increase in input shaft speed 
(ES=IS=OS.times.GR.sub.T). For upshifts, where input shaft speed must 
generally be decreased, reduced fueling of the engine with the clutch 16 
engaged and/or application of the inertia brake 28 with the master clutch 
16 disengaged will accomplish the necessary decrease in input shaft speed, 
as well as providing a torque break. Alternatively, as is known in the 
prior art, input shaft speed may be decreased for upshifting by 
maintaining the clutch 16 engaged while applying an engine brake, such as 
an engine compression brake or an exhaust brake, such as a well-known 
"Jake brake," as is well known in the heavy truck industry (see 
aforementioned U.S. Pat. No. 5,409,432). As a further prior art 
alternative embodiment, increasing and decreasing of the input shaft 
rotational speed and the rotational speed of the transmission members 
rotating therewith was accomplished by means of a power synchronizing 
device of the type illustrated in aforementioned U.S. Pat. No. 4,614126. 
When an initial throttle dip is commanded to allow a shift into neutral, 
the clutch is also commanded to be disengaged and is expected to disengage 
in about 0.20 to 0.50 seconds. Upon sensing transmission neutral, for 
downshifts, the clutch is commanded to reengage. 
The throttle control system or assembly 36 of the present invention for 
controlling the fueling of non-electronically controlled engine 14 may be 
seen by reference to FIG. 2. The throttle control assembly 36 includes a 
throttle control piston and cylinder assembly 54 comprising a throttle 
control piston 56, which is slidably received in a cylinder 58 and is 
displaceable rightwardly to increase fueling of the engine and leftwardly 
to decrease fueling of the engine. A spring 60 biases the actuator piston 
56 leftwardly toward the idle fueling position thereof. The piston 56 is 
responsive to pressurization in chamber 62 to move rightwardly against the 
bias of spring 60 to increase the fueling of the engine. 
A three-way, two-position, solenoid-controlled valve S2 is provided to 
connect conduit 64, which is in fluid communication with piston chamber 
62, with either a conduit 66 selectively pressurized in accordance with 
the output 68 from the throttle control module 30 or with a conduit 70 
controlled by a further solenoid-controlled valve S1, to be described in 
greater detail below. With the solenoid 72 of the solenoid-controlled 
valve S2 in the non-energized condition, conduit 66 is connected to 
conduit 64, conduit 70 is blocked, and the fueling of the engine 14 is 
under the direct control of the operator by means of manipulation of the 
throttle pedal 32. 
A further three-way, two-position, solenoid-controlled valve S1 is 
operative to connect the conduit 70 to either an exhaust or to a source of 
pressurized fluid, such as air supply 74 via conduit 76. With solenoid 78 
of the solenoid-controlled valve S1 in the non-energized or deenergized 
position, conduit 70 is connected to exhaust and the pressurized conduit 
76 is blocked. When the solenoid 78 of valve S1 is energized, pressurized 
conduit 76 is fluidly communicated with conduit 70 while the exhaust is 
blocked. 
FIG. 3 illustrates the throttle control system 36 in its normal condition 
thereof with solenoid-controlled valves S1 and S2 in their deenergized 
positions wherein the positioning of the throttle-control piston 56 is 
controlled directly in accordance with output 68 from the throttle pedal 
32. 
FIG. 4 illustates the throttle control assembly 36 in the throttle dip mode 
of operation wherein fueling to engine 14 is decreased, regardless of the 
magnitude of signal 68, allowing the engine speed to decrease toward the 
idle speed thereof. In the throttle dip mode of operation, solenoid valve 
S1 remains deenergized, while solenoid 72 of valve S2 is energized. This 
causes the solenoid valve S2 to connect conduit 64 and chamber 62 to 
exhaust through conduit 70 and solenoid-controlled valve S1 , while the 
conduit 66 connected to the operator's pneumatic signal 68 is blocked by 
the solenoid-controlled valve S2. As may be seen and as may be appreciated 
in greater detail by reference to logic block 80 and/or to FIGS. 9A and 9B 
(which illustrate the shift control logic of transmission system 10 in a 
flow chart format), solenoid-controlled valves S1 and S2 may be commanded 
to assume the throttle dip positions thereof without requiring that master 
clutch 16 be disengaged and/or that transmission 12 be in neutral. 
FIG. 5 illustates the throttle control assembly 36 of the present invention 
in the throttle blip or fuel increasing condition thereof. In the throttle 
blip mode of operation, solenoid valves S1 and S2 both assume the 
energized positions thereof, causing piston chamber 62 to be connected to 
the air supply 74 by a conduit 76, solenoid-controlled valve S1, conduit 
70, solenoid-controlled valve S2 and conduit 64. In this position, conduit 
66 pressurized in accordance with the operator pedal position signal 68 is 
blocked by solenoid-controlled valve S2 and the throttle-controlled piston 
56 is moved rightwardly toward the full throttle position thereof, 
regardless of the magnitude of signal 68. It is noted that energization of 
both solenoidcontrolled valves S1 and S2 requires that the driveline be 
disengaged by means of disengaging either clutch 16 or transmission 12 by 
causing transmission 12 to assume the neutral condition thereof. The 
requirement for disengagement of the driveline is symbolically illustrated 
in logic block 82 in FIG. 5. Preferably, during throttle boost operations, 
if target engine speed is not achieved within a period of time (such as 
five seconds, for example), control of fueling is returned to the 
operator. 
Valves S1 and S2 may be pulse-width-modulation-controlled to control the 
rate of increased and decreased fueling of the engine. 
FIGS. 6-8 illustrate the throttle control system of the present invention 
in various single point failure modes thereof. Not illustrated is a 
failure mode wherein, during a throttle blip, both solenoid-controlled 
valves S1 and S2 fail in the off position. In such a situation, the 
throttle control system will assume the normally non-energized condition 
illustrated in FIG. 3 and the engine 14 will be fueled in accordance with 
the operator's setting of the throttle pedal 32. Upon sensing a failure at 
one or both of the valves S1, S2, the driver or maintenance department 
will be notified and appropriate fault tolerance and/or failsafe routines 
implemented. 
FIG. 6 illustrates a single point failure wherein solenoid-controlled valve 
S1 has failed to the on or energized position, which may be the result of 
an improperly energized solenoid 74 or may be result of the valve's 
sticking in the illustrated position. Solenoid-controlled valve S2 is 
properly in the deenergized position. In this situation, piston chamber 62 
will continue to be operated in accordance with the output signal 68 from 
the throttle pedal, while the solenoid-controlled valve S2 will block 
pressurized air in the conduit 70 from the air supply and conduit 76 
through failed valve S1 from reaching the conduit 64. Accordingly, in this 
position, the single point failure of the solenoid-controlled valve S1 
will not affect the fueling of the engine under normal operating 
conditions. 
In Fig. 7, a failure mode is indicated wherein the solenoid-controlled 
valve S1 is in the off position and the other solenoid-controlled valve, 
S2, has failed to the on or energized position. In this situation, the 
throttle control system 36 assumes the "fuel dip" configuration, as 
illustrated in FIG. 4, and the engine is caused to assume the idle fueled 
condition. While this is a highly undesirable and inconvenient situation, 
it is not considered to be a safety problem, as the engine is not caused 
to be unintentionally fueled in a maximum manner with the drivetrain 
engaged. 
As a safety feature, see FIGS. 9A and 9B, which are flow chart 
representations of the shift control logic rules for controlling automated 
mechanical transmission system 10, when a throttle dip has been commanded 
(i.e., when solenoid-controlled valve S1 is caused to assume the off or 
deenergized position and solenoid-controlled valve S2 is caused to assume 
the on or energized position), a throttle dip flag is set, a timer is 
started, and an initial engine speed, ES.sub.o, is memorized. At the 
expiration of a referenced period of time (such as, for example, one 
second) and during continued throttle dip conditions, if the engine speed 
equals or exceeds the initial engine speed or a decremental value thereof 
(T&gt;REF and ES&gt;ES.sub.o ?), an engine control error is declared and the 
solenoid-controlled valve S2 is commanded to assume the off or deenergized 
position thereof. Alternatively and/or additionally, upon sensing an 
engine control error, the master clutch 16 may be commanded to the 
disengaged position thereof. Further energization of valves S1 and S2 is 
prevented and/or further shifting prohibited. 
FIG. 8 illustrates a single point failure of throttle control assembly 36 
wherein, during a throttle dip operation in which the solenoid-controlled 
valve S2 is in the on or energized position, the other solenoid-controlled 
valve, S1, fails to the on or energized position. In this situation, as a 
result of the single point failure at solenoid S1, the throttle control 
system 36 will assume the undesirable configuration wherein, during a 
desired throttle dip operation, engine fueling is increased rather than 
decreased, while the drivetrain may be momentarily in an engaged 
condition. While this is highly undesirable, the single point failure at 
solenoid-controlled valve S1 will cause this condition to exist only until 
such time as is required to cause the transmission to shift to neutral or 
the master clutch 16 to disengage or to declare an engine control error, 
which will result in the solenoid-controlled valve S2's being returned to 
the off or deenergized condition (see FIG. 6) wherein the fueling of the 
engine will again be controlled by the operator's setting of the throttle 
pedal. 
Of course, when one or more throttle control system faults are sensed, the 
driver will be notified of a potentially unsafe condition and should pull 
off the road in a safe manner and/or seek maintenance at the earliest 
opportunity. Alternatively, upon sensing a single point failure, the 
driver may be notified that the vehicle will remain operational only for a 
limited period of time (such as five or ten minutes) to allow him to bring 
the vehicle safely to a more desirable location. 
The control logic for controlling automated mechanical transmission 10 
during up- and downshifts into a target gear ratio are schematically 
illustrated in flow chart format in FIGS. 9A and 9B. 
While the fuel control assembly 36 is illustrated as pneumatically 
controlled, it could be hydraulically and/or electrically actuated. In an 
electrically actuated embodiment, the valves S1 and S2 may be replaced by 
switches or the like, and the piston/cylinder assembly may be replaced by 
a stepper motor or the like. 
Although the present invention has been described with a certain degree of 
particularity, it is understood that various modifications are possible 
without departing from the spirit and the scope of the invention as 
hereinafter claimed.