BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a compound change gear vehicular
transmission having an input auxiliary section, preferably of the splitter type,
connected in series with a mechanical main transmission section, preferably of
the synchronized type. In particular, the present invention relates to a compound
change gear transmission having an input auxiliary section utilizing selectively
and modulatably engagable and disengagable friction clutches having an input non-disengagably
drivingly mechanically connected to the vehicle prime mover whereby the auxiliary
section friction clutches, in addition to allowing auxiliary section gear changing,
provide the engagement/disengagement functions of a master clutch.
Description of the Prior Art
Compound mechanical transmissions of the input splitter type and
compound transmissions utilizing input auxiliary sections having friction clutch
devices are known in the art as may be seen by reference to U.S. Patents No. US-A-4
485 692; 2 886 982 and 3 741 035.
Automatic and semi-automatic transmission and clutch controls are
known in the prior art as may be seen by reference to U.S. Patents Nos. US-A-4
648 290; 4 361 060 and 4 081 065.
Synchronized mechanical change gear transmissions and transmission
sections are well known in the prior art as may be seen by reference to U.S. Patents
Nos. US-A-4 432 251; 4 373 403 and 4 018 319.
While compound mechanical (i.e. engaging ratios by means of positive
clutches) change gear transmissions having input auxiliary sections of the splitter
type and/or using friction clutches are know, such transmissions have required
the use of a disconnect member, such as a master clutch or torque converter, between
the transmission and prime move and/or have been of a relatively high inertia
resulting in more difficult and/or higher energy synchronization of the main transmission
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 compound vehicular transmission
comprising an input auxiliary section, preferably of the splitter type, connected
in series between the vehicle engine and the mechanical main transmission section,
preferably a synchronized type transmission section. The auxiliary input section
utilizes a friction clutch, preferably a liquid lubricated and/or cooled friction
clutch having an input that is nondisengagably mechanically connected to the engine.
The auxiliary section friction clutch has at least two selectable engaged positions
for selection of one of two selectable input ratios and a selectable disengaged
position. By moving the auxiliary section friction clutch between its selected
engaged position and the disengaged position, the torque break function of a master
clutch is provided.
The auxiliary section friction clutch is positioned by either the
controller of an automatic/semi-automatic transmission system or by an electrical/mechanical
actuator responsive to manual transmission and clutch control devices. Preferably,
a mechanical disconnect, such as a jaw clutch, is provided between the auxiliary
input section friction elements and the main transmission section input to allow
the rotational inertia of the main transmission section input to be minimized for
easier, quicker, lower energy synchronization of the main transmission section
during a main transmission section ratio change.
Accordingly, it is an object of the present invention to provide
a new and improved compound transmission having an input auxiliary section utilizing
selectively engaged/disengaged friction clutch means and drivingly mechanically
nondisengagably connected to a prime mover.
This and other objects and advantages of the present invention will
become apparent from a reading of the detailed description of the preferred embodiments
taken in connection with the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic illustration of an automatic or semi-automatic
mechanical transmission system utilizing the auxiliary transmission input section
of the present invention.
Figure 2 is a schematic illustration of a manually controlled transmission
system utilizing the auxiliary transmission input section of the present invention.
Figure 3 is an enlarged schematic illustration of the auxiliary transmission
input section of the present invention.
Figure 4 is a schematic illustration of the shift pattern of the
transmission illustrated in Figure 2.
Figure 5 is a sectional view of the auxiliary transmission input
section of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Certain terminology will be used in the following description for
convenience and reference only and will not be limiting. The words "upperly", "downwardly",
"rightwardly" and "leftwardly" will designate directions in the drawings to which
reference is made. The words "forward" and "rearward" will refer respectively
to the front and rear end of the transmission as same as conventionally mounted
in the vehicle, being respectively from left to right sides of the transmission
as illustrated in Figure 1. The words "inwardly" and "outwardly" will refer to
directions toward and away from, respectively, being the geometric center of the
device and designated parts thereof. Said terminology will include the words above
specifically mentioned, derivatives thereof and words with similar import.
The term "compound transmission" is used to designate a transmission
having a main transmission section and an auxiliary transmission section connected
in series whereby the selected gear reduction in the main transmission section
may be compounded by further selected gear reduction in the auxiliary transmission
portion. The term "input auxiliary section" is used to designate auxiliary transmission
section connected in series between the vehicular prime mover, such as a vehicle
engine, and the input to the main transmission section. The term "splitter type
compound transmission" as used herein will designate the compound transmission
wherein the auxiliary transmission is used to provide various selectable steps
for subdivisions of the gear ratio selected in the main transmission section. In
a splitter type compound transmission, the main transmission section is typically
provided with relatively wide ratio steps which are split or subdivided by the
splitter type auxiliary transmission section. Splitter type compound transmissions
are well known in the prior art and examples thereof may be seen by to reference
to the above-mentioned United States Patent Nos. US-A-4 485 692 and 3 741 035 and
by reference to European Patent No. EP-A-0071353.
The term "synchronized transmission section" shall designate a change
gear transmission section wherein a selected gear is non-rotatably coupled to a
shaft by means of a positive clutch, attempted engagement of said clutch is prevented
until the members of said clutch are rotating at a substantially synchronous rotational
speed and frictional means associated with the clutch members are sufficient,
upon the initiation of a clutch engagement, to cause the clutch members, and all
members rotating therewith, to rotate at a substantially synchronous speed of
An automatic/semi-automatic mechanical transmission system 10 utilizing
the auxiliary input section of the present invention may be seen by reference
to Figure 1. Briefly, a vehicular prime mover such as engine 12 is drivingly coupled
to compound change gear transmission 14 which comprises an input auxiliary transmission
section 18 connected in series with mechanical change gear main transmission section
20. A transmission input shaft 22 mechanically drivingly connects, in a nondisengable
manner, the vehicular engine 12 with the transmission 14 while a transmission output
shaft 24 is drivingly connected to the vehicular drive wheels as is well known
in the prior art.
A central processing unit 16 receives input signals from the main
transmission section 20, the auxiliary transmission section 18, the engine 12 and
other input devices 26, such as throttle position, gear selection position and
like sensors and processes the same in accordance with predetermined logic rules
to generate command output signals to actuators provided in the engine and transmission
for automatic or semi-automatic operation of transmission system 10. Automatic/semi-automatic
mechanical transmission systems and the sensors, actuators and controller associated
therewith are known in the prior art and may be appreciated in greater detail by
reference to above-mentioned United States Patent Nos. US-A-4 648 290; 4 361 060
and 4 081 065.
A schematic illustration and a sectional view of the detailed structure
of the input auxiliary transmission section 18 may be seen by reference to Figures
3 and 5. Briefly, transmission input shaft 22 is mechanically nondisengagably
connected to the vehicular engine. A plate 22A may be fixed to shaft 22 for mounting
to the engine flywheel. The transmission input shaft 22 carries an auxiliary section
input gear 30 rotationally movable relative thereto which is constantly meshed
with auxiliary section countershaft gear 32 carried by auxiliary section countershaft
34. Auxiliary section countershaft 34 is supported by bearings 36 in auxiliary
section housing 38 which is preferably attached to and/or integral with main transmission
section housing 40. The auxiliary section countershaft 34 also carries a second
auxiliary section countershaft gear 42 which is constantly meshed with auxiliary
section output gear 44. The auxiliary section output gear 44 is rotatably fixed
to auxiliary section output shaft 46 which defines the input to main transmission
section 20 and carries the main transmission section input gear 48 fixed thereto.
Preferably, main transmission section 20 is a simple transmission of the synchronized
transmission type as is well known in the prior art and as may be appreciated in
greater detail by reference to above-mentioned United States Patent Nos. US-A-4
432 251; 4 373 403 and 4 018 319.
The auxiliary input transmission section 18 includes a friction clutch
assembly 50 having a first position for frictionally drivingly connecting transmission
input shaft 22 to the auxiliary transmission output shaft 46 and output gear 44
while allowing free rotation between the input shaft 22 and input gear 30 to provide
a one-to-one ratio, or direct drive relationship, between input shaft 22 and auxiliary
section output shaft 46. In a second position of clutch assembly 50, input shaft
22 is rotationally disengaged from auxiliary section output shaft 46 and auxiliary
output gear 44 and is rotationally coupled to auxiliary section input gear 30 to
provide a selectable speed reduction between the auxiliary section output shaft
46 as compared to the rotational speed of input shaft 22. Preferably, as discussed
above, the gear reduction obtained in the second position of clutch assembly 50
will be less than the average ratio step of the main transmission section, preferably
equal to approximately the square root of the average main transmission section
ratio step, whereby auxiliary transmission section 18 will be a splitter type
input auxiliary transmission section for main transmission section 20 of compound
The clutch assembly 50 will also have a third disengaged position
wherein the input shaft 22 is independently rotatable of the auxiliary section
output shaft 46.
Preferably, the central processing unit 16 will be provided with
logic rules whereby the clutch assembly 50 may be selectively positioned from the
selected one of the first and second position thereof and the third disengaged
position allowing the clutch assembly to function in a manner functionally comparable
to a vehicular master clutch in providing a break in torque between the vehicle
engine and the main transmission section 20. Preferably, to provide adequate vehicle
start from stop operation, the clutch will be engaged and disengaged in a controlled
modulated manner as set forth in above-mentioned United States Patent No. US-A-4
Referring now specifically to the structure of clutch assembly 50,
auxiliary section input shaft 22, carries a first set 52 and a second set 54 of
clutch discs rotationally fixed thereto, input gear 30 carries a plurality of
clutch discs 56 interleaved with clutch discs 52 to define a clutch disc pack 58.
Auxiliary section output gear 44 carries a plurality of friction clutch discs
60 for rotation therewith which clutch discs are interleaved with clutch disc 54
to define a second clutch disc pack 62. A three position actuator 64 is provided
for engaging disc pack 58 for coupling input shaft 22 to input gear 30, for engaging
disc pack 62 for coupling auxiliary section input shaft 22 to auxiliary section
output shaft 46 or for maintaining both of the disc packs 58 and 62 in the disengaged
positions thereof. Actuator 64 may be mechanical, pneumatic, or the like. Preferably,
clutch assembly 50 is enclosed within a housing 38, is liquid cooled and utilizes
friction material containing substantially pyrolytic carbon. Wet or liquid cooled
friction clutches of this type are known in the prior art and may be seen in greater
detail by reference to United States Patent No. US-A-4 291 754.
Of course, gear 30 could be rotationally fixed to shaft 22 and gear
44 rotatable relative to shaft 46 and frictionally coupable thereto.
To lower the rotational inertia of the auxiliary section output shaft
46 to provide easier, quicker and lower energy synchronization of main transmission
section 20, a positive clutch device, such as jaw clutch 66 (illustrated in Figure
3 only) is provided in auxiliary output shaft 46 interposed the auxiliary section
clutch assembly 50 and the main transmission section input gear 48. Briefly, during
a shift transcend in main transmission section 20, the mechanical coupling 66 will
be opened to disengage the rearward portion of auxiliary section output shaft
46 from the rotational inertia of the auxiliary section clutch assembly 50. Preferably,
with the clutch assembly 50 in the disengaged position, the coupling 66 may be
easily re-engaged after achievement of a synchronous engagement of a selected gear
in the main transmission section 20 without requiring synchronization of the members
thereof due to the relatively low inertia of the forward portion of auxiliary section
output shaft 46.
An alternate embodiment of the present invention may be seen by reference
to Figures 2 and 3. Briefly, Figure 2 illustrates a manually controlled transmission
system 70 utilizing the compound transmission 14 discussed above in connection
with Figure 1. Briefly, control of the auxiliary section clutch 50 and, if utilized,
a positive disconnect coupling 66, is by means of a controller 72 which is responsive
to input signals from the clutch pedal 74 and from the shift selector lever 76
which comprises a shift lever 78 for shifting the main transmission section and
the switch 80 for selecting the direct drive or gear reduction ratio of the input
auxiliary transmission section 18. Briefly, selector switch 80 will determine which
of the clutch packs 58 or 62 is to be selectively engaged or disengaged while
the position of clutch pedal 74 will determine the degree of engagement or disengagement
of the selected clutch pack. Should mechanical disconnect 66 be utilized with
transmission system 70, a sensor may be provided for sensing a gear change in the
main transmission section 20 for causing control 72 to cause the coupling 66 to
assume the disconnect position thereof.
The shift pattern for transmission system 70 may be seen by reference
to Figure 4.