Manually shifted transmission with enhanced automatic range shift

A manually shifted, range-type compound transmission (110) is provided with enhanced automatic range shifting. A controller (222) receives input signals indicative of shift lever position in the shift pattern (low range/high range) and of vehicle speed (OS) and automatically commands range shifts as a function of both system parameters.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to manually shifted range-type compound 
transmissions having enhanced automatic range shifting mechanisms and 
controls. In particular, the present invention relates to manually shifted 
range-type transmissions of the "H 1/2" or "double-H" type having an 
"autorange" type shift mechanism of the general kind disclosed in U.S. 
Pat. Nos. 3,492,202; 4,275,612; 4,455,883; 5,000,060 and 5,193,410, the 
disclosures of which are incorporated herein by reference, wherein the 
range shift controller will prevent range shifting at vehicle speeds at 
which such shifting is predetermined to be inappropriate. 
2. Description of the Prior Art 
Change-gear transmissions of the range type and of the combined 
range-and-splitter type are well known in the prior art, as may be seen by 
reference to U.S. Pat. Nos. 4,455,883; 4,754,665; 5,193,410; 5,000,060 and 
5,390,561, the disclosures of which are incorporated herein by reference. 
Range-type transmissions having shift controls of the "multiple-H" type, 
as opposed to the "repeat-H" type, which utilize an automatic range shift 
mechanism responsive to movement of a shift lever from a first to a second 
area or portion of the shift pattern, are well known, as may be seen by 
reference to aforementioned U.S. Pat. Nos. 4,455,883; 4,974,468; 5,000,060 
and 5,193,410. 
While the prior art manually shifted, range-type transmissions utilizing 
automatic range shifting controls are widely used and commercially 
successful, they are not totally satisfactory, as, due to error or 
inattention, an operator may select a range shift inappropriate under 
current vehicle speed conditions, which shift will be automatically 
completed by the range actuator and usual synchronized range clutch 
assembly. 
SUMMARY OF THE INVENTION 
According to the present invention, the drawbacks of the prior art are 
minimized or overcome by the provision of an enhanced automatic range 
shifting mechanism and control for manually shifted, range-type 
transmissions which will prevent range shifts from being implemented at 
inappropriate vehicle speeds, regardless of shift lever movement from one 
range section to another range section of the manual shift pattern. The 
foregoing is accomplished in a manually shifted transmission with an 
automatic range shifting system by providing a controller for sensing the 
value of a parameter indicative to vehicle speed, as well as sensing shift 
lever positioning, and for permitting downshifts only if vehicle speed is 
less than a first reference value and/or permitting upshifts only if 
vehicle speed is greater than a second reference value. 
Accordingly, it is an object of the present invention to provide a new and 
improved automatic range shifting mechanism and control for manually 
shifted, range-type transmissions. 
This and other objects and advantages of the present invention will become 
apparent from a reading of the following description of the preferred 
embodiment taken in connection with the attached drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In FIGS. 1, 2 and 3, manually shifted transmission 110 of the type 
advantageously utilizing the enhanced automatic range shifting mechanism 
and control of the present invention is illustrated. Transmission 110 
includes a main section 112 and an auxiliary section 114, both contained 
within housing 116. Housing 116 includes a forward end wall 116A and a 
rearward end wall 116B, but not an intermediate wall. 
Input shaft 118 carries input gear 120 fixed for rotation therewith and 
defines a rearwardly opening pocket 118A wherein a reduced diameter 
extension 158A of output shaft 158 is piloted. A non-friction bushing 118B 
or the like may be provided in pocket or blind bore 118A. The forward end 
of input shah 118 is supported by bearing 118C in front end wall 116A, 
while the rearward end 158C of output shaft 158 is supported by bearing 
assembly 158D in rear and wall 116B. Bearing assembly 158D may be a pair 
of opposed taper bearings or a single roller or ball bearing, as is 
illustrated in FIG. 3. 
The mainshaft 146, which carries mainshaft clutches 148 and 150, and the 
mainshaft splitter clutch 180 is in the form of a generally tubular body 
146A having an externally splined outer surface 146B and an axially 
extending through bore, 146C for passage of output shaft 158. Shift forks 
152 and 154 are provided for shifting clutches 148 and 150, respectively. 
Mainshaft 146 is independently rotatable relative to input shaft 118 and 
output shaft 158 and preferably is free for limited radial movements 
relative thereto. 
The main section 112 includes two substantially identical main section 
countershaft assemblies 122 each comprising a main section countershaft 
124 carrying countershaft gears 130, 132, 134, 136 and 138 fixed thereto. 
Gear pairs 130, 134, 136 and 138 are constantly meshed with input gear 
118, mainshaft gears 140 and 142 and idler 157, which is meshed with 
reverse mainshaft gear 144, respectively. 
Main section countershaft 124 extends rearwardly into the auxiliary 
section, where its rearward end 124A is supported directly or indirectly 
in rear housing end wall 116B. 
The auxiliary section 114 includes two substantially identical auxiliary 
countershaft assemblies 160, each including an auxiliary countershaft 162 
carrying auxiliary countershaft gears 168, 170 and 172 for rotation 
therewith. Auxiliary countershaft gear pairs 168, 170 and 172 are 
constantly meshed with splitter gear 174, splitter/range gear 176 and 
range gear 178, respectively. Splitter, clutch 180 is fixed to mainshaft 
146 for selectively clutching either gear 174 or 176 thereto, while 
synchronized range clutch 182 is fixed to output shaft 158 for selectively 
clutching either gear 176 or gear 178 thereto. 
Auxiliary countershafts 162 are generally tubular in shape, defining a 
through bore 162A for receipt of the rearward extensions of the main 
section countershafts 124. Bearings or bushings 162B and 162C are provided 
to rotatably support auxiliary countershaft 162 on main section 
countershaft 124. Bearing 162D directly or indirectly supports the rear 
ends of countershafts 124 and 162 in the rear end wall 116B. 
The splitter jaw clutch 180 is a two-position, non-synchronized clutch 
assembly which may be selectively positioned in the rightwardmost or 
leftwardmost positions for engaging either gear 176 or gear 174, 
respectively, to the mainshaft 146. Splitter jaw clutch 180 is axially 
positioned by means of a shift fork 184 controlled by a two- or 
three-position piston actuator, which is responsive to a driver selection 
switch such as a button or the like on the shift knob, as is known in the 
prior art. Two-position synchronized range clutch assembly 182 is a 
two-position clutch which may be selectively positioned in either the 
rightwardmost or leftwardmost positions thereof for selectively clutching 
either gear 178 or 176, respectively, to output shaft 158. Clutch assembly 
182 is positioned by means of a shift fork 188 operated by means of a 
two-position piston device 189. 
As may be seen by reference to FIGS. 2 and 3, by selectively axially 
positioning both the splitter clutch 180 and the range clutch 182 in the 
forward and rearward axial positions thereof, four distinct ratios of 
mainshaft rotation to output shaft rotation may be provided. Accordingly, 
auxiliary transmission section 114 is a three-layer auxiliary section of 
the combined range and splitter type providing four selectable speeds or 
drive ratios between the input (mainshaft 146) and output (output shaft 
158) thereof. The main section 112 provides a reverse and three 
potentially selectable forward speeds. However, one of the selectable main 
section forward gear ratios, the low-speed gear ratios associated with 
mainshaft gear 142, is not utilized in the high range. Thus, transmission 
110 is properly designated as a "(2+1).times.(2.times.2)" type 
transmission providing nine or ten selectable forward speeds, depending 
upon the desirability and practicality of splitting the low gear ratio. 
The shift pattern for shifting transmission 110 is schematically 
illustrated in FIG. 3. Divisions in the vertical direction at each gear 
lever position signify splitter shifts, while movement in the horizontal 
direction from the 3/4 and 5/6 leg of the H pattern to the 7/8 and 9/10 
leg of the H pattern signifies a shift from the low range to the high 
range of the transmission. As discussed above, splitter shifting is 
accomplished responsive to a vehicle operator-actuated splitter button or 
the like, usually a button located at the shift lever knob, while 
operation of the range clutch shifting assembly is an automatic response 
to movement of the gear shift lever between the central and rightwardmost 
legs of the shift pattern (i.e., between the low range and high range 
portions, respectively), as illustrated in FIG. 3, and as will be 
described in greater detail below. Automatic range shift devices of this 
general type for manual shift transmissions are known in the prior art and 
may be seen by reference to U.S. Pat. Nos. 3,429,202; 4,275,612; 4,455,883 
and 5,000,060. 
Referring again to FIG. 3, and assuming it is desirable that a transmission 
have generally equal ratio steps, the main section ratio steps should be 
generally equal, the splitter step should be generally equal to the square 
root of the main section ratio steps, and the range step should equal 
about the main section ratio step raised to the N.sup.TH power where 
N.sup.TH equals the number of main section ratio steps occurring in both 
ranges (i.e., N=2 in the (2+1).times.(2.times.2) transmission 110). Given 
the desired ideal ratios, gearing to approximate these ratios is selected. 
In the above example, the splitter steps are about 33.3%, while the range 
step is about 316%, which is generally suitable for a "2+1" main 
transmission section having about 78% steps, as the square root of 1.78 
equals about 1.33 and 1.78 raised to the second power (i.e., N=2) equals 
about 3.16. 
Transmissions similar to transmission 110 may be seen in greater detail by 
reference to aforementioned U.S. Pat. Nos. 4,754,665; 5,368,145 and 
5,390,561. 
Although the present invention is illustrated in the embodiment of a 
compound transmission not having an intermediate wall, the present 
invention is equally applicable to transmissions of the type illustrated 
in U.S. Pat. Nos. 4,754,665; 5,193,410 and 5,368,145. 
As mentioned above, in the prior art, especially for manually shifted, 
range-type transmissions with an automatic range shifting mechanism, the 
synchronized range section clutch occasionally would complete range shifts 
selected in error or due to inattention, even if such shifts were 
undesirable under current vehicle speed conditions. By way of example, if 
during an intended 8th-to-9th speed shift at relatively high vehicle 
speeds, the shift lever is incorrectly moved to the 3/4-5/6 leg, or worse 
yet, to the R.sub.L /R.sub.H -1/2 leg, and then moved downwardly into the 
engaged position, the shift, if completed, will be harsh with potential 
undue wear and/or damage to the synchronizer, the clutch teeth, the 
transmission and/or the vehicle. Similarly, if a range upshift is 
completed at an excessively low vehicle speed, the engine may be stalled 
and/or the shift undesirably harsh. Such inappropriate range shifting may 
become more likely if biasing means are not utilized to inhibit movement 
of the shift lever between legs of the shift pattern. 
The range clutch 182 is moved by a shift fork 188 attached to an actuator 
piston 200 of the piston device 189. The actuator assembly 202 includes 
the piston device 189 and a valve device 203 operated by command output 
signals which may be electrical, fluidic and/or mechanical. The valve 
device 203 controls a selectively pressurized and exhausted chamber 204 to 
achieve the two positions (H, L) of the shift fork. Alternatively, as seen 
in aforementioned U.S. Pat. No. 5,000,060, an additional valve (not shown) 
responsive to command signals may be provided to selectively pressurize 
and exhaust the lefthand chamber of the actuator piston/cylinder assembly. 
FIG. 5 illustrates a vehicular powertrain 206 utilizing the present 
invention. Powertrain 206 includes an internal combustion engine 208, a 
master clutch 210 and manually shifted, range-type transmission 110. A 
shift lever 212 operates a shift mechanism 214, such as a single shift 
shaft mechanism of the type illustrated in U.S. Pat. No. 4,920,815, the 
disclosure of which is incorporated herin by reference. 
The shift lever 214 includes a knob 216 carrying a splitter master valve 
and selector 218 by which splitter high (H) or splitter low (L) may be 
selected. 
A microprocessor-based controller 222 receives input signals 224 and 
processes same according to predetermined logic rules to issue command 
output signals 226 to various system actuators, including the range clutch 
actuator 202. The microprocessor 222 may be of the type illustrated in 
U.S. Pat. No. 4,595,986, the disclosure of which is incorporated herein by 
reference. 
The engine 208 may include an electronic controller 209 communicating over 
an electronic data link DL utilizing the SAE J-1922, SAE J-1939 and/or ISO 
11898 protocol. Sensors also may be provided to provide input signals 
indicative of input shaft (IS) and/or output shaft (OS) rotational speeds 
and/or of the position of the shift lever (GL). Output shaft speed is 
indicative of vehicle ground speed. 
As may be seen by reference to FIG. 6, the controller 222 is provided with 
logic rules under which an automatic range upshift requires that the shift 
lever be moved into the range-high portion of the shift pattern (7/8-9/10 
leg) and that vehicle speed be greater than a reference value 
(OS&gt;REF.sub.2), while an automatic range downshift requires that the shift 
lever be moved into the range-low portion of the shift pattern (R.sub.L 
/R.sub.H -1/2 or 3/4-5/6 leg) and vehicle speed be less than a reference 
value (OS&lt;REF.sub.1). The logic also may require that main section neutral 
exists prior to commanding a range shift. By way of example, for 
heavy-duty diesel engines and transmissions of the type illustrated, no 
automatic range upshift would be permitted below about 5-15 MPH, while no 
automatic range downshift would be permitted above about 25-35 MPH. 
Although the present invention has been described with a certain degree of 
particularity, it is understood that the description of the preferred 
embodiment is by way of example only and that numerous changes to form and 
detail are possible without departing from the spirit and scope of the 
invention as hereinafter claimed.