Hydraulic control systems for dual clutch transmissions

The present invention comprehends a plurality of embodiments of a hydraulic control system for various configurations of dual clutch transmissions. The hydraulic control systems all include a regulated source of pressurized hydraulic fluid including an electric pump, a filter and an accumulator, a pair of pressure control valves and a branching hydraulic circuit including pressure or flow control valves, spool or logic valves and two position valves which collectively supply and exhaust hydraulic fluid from a plurality of shift actuators. The actuators are connected to shift rails which include shift forks and are slidable to engage synchronizers and positive clutches associated with the various gear ratios.

FIELD

The present disclosure relates to hydraulic control systems and more particularly to hydraulic control systems and their components for dual clutch transmissions.

BACKGROUND

In automotive transmission art, the dual clutch transmission (DCT) is a relatively new concept. A typical dual clutch transmission configuration includes a pair of mutually exclusively operating input clutches which drive a pair of input shafts. The input shafts may be disposed on opposite sides of an output shaft or may be disposed concentrically between spaced-apart output shafts. One of each of a plurality of pairs of constantly meshing gears which provide the various forward and reverse gear ratios is freely rotatably disposed on one of the shafts and the other of each pair of gears is coupled to one of the other shafts. A plurality of synchronizer clutches selectively couple the freely rotatable gears to the associated shaft to achieve forward and reverse gear ratios. After the synchronizer clutch is engaged, the input clutch associated with the input shaft having the engaged synchronizer clutch is applied to transmit power through the transmission. Reverse gear is similarly achieved except that it includes an additional (idler) gear to provide torque reversal.

Dual clutch transmissions are known for their sporty, performance oriented operating characteristics which mimic those of a conventional mechanical (manual) transmission. They also typically exhibit good fuel economy due to their good gear mesh efficiency, ratio selection flexibility, reduced clutch losses and the lack of a torque converter.

There are, however, design considerations unique to dual clutch transmissions. For example, because of heat generated during clutch slip, the input clutches must be of relatively large size. Furthermore, such heat generation typically requires correspondingly larger and more complex cooling components capable of dissipating relatively large quantities of heat. Finally, because such transmissions typically have many sets of axially aligned, meshing gears, their overall length may limit their use to certain vehicle designs.

Control of the input clutches and selection and engagement of a particular gear by translation of a synchronizer and associated positive clutch is typically achieved by a hydraulic control system. Such a system, itself under the control of an electronic transmission control module (TCM), includes hydraulic valves and actuators which engage the synchronizers and gear clutches. Optimum operating efficiency and thus fuel efficiency and minimal heat generation can be achieved by designing such hydraulic control systems to exhibit low leakage and positive control characteristics. The present invention is so directed.

SUMMARY

The present invention comprehends a plurality of embodiments of a hydraulic control system for various configurations of dual clutch transmissions having two or three countershafts, a third, idler shaft and four or five shift rails and hydraulic actuators. The hydraulic control systems all include a regulated source of pressurized hydraulic fluid including an electric pump, a filter and an accumulator, a pair of pressure control valves and a branching hydraulic circuit including pressure or flow control valves, spool or logic valves and two position valves which collectively supply and exhaust hydraulic fluid from a plurality of shift actuators. The actuators are connected to shift rails which include shift forks and are slidable to engage synchronizers and positive clutches associated with the various gear ratios.

Several of the embodiments define two essentially independent control systems supplied with hydraulic fluid through two independently operating valves. The two independent control systems are associated with respective transmission countershafts and, generally speaking, one countershaft is associated with the even-numbered gears (second, fourth, etc.) and the other countershaft is associated with the odd-numbered gears (first, third, etc.). When the transmission is operating in a normal ascending or descending gear selection sequence, this configuration permits pre-staging or pre-selection of a gear associated with one countershaft while a gear associated with the other countershaft is engaged and transmitting torque. Furthermore, if a component or components associated with one countershaft fail, the other countershaft and the alternating (i.e., first, third, fifth) selection of gear ratios it provides will still be fully operational—a highly desirable failure mode.

The hydraulic control systems according to the present invention are less complex and expensive relative to competing systems, provide improved control through interconnected logic valves which reduce the likelihood of engaging a wrong or multiple gears and provide reduced energy consumption by allowing shut-down of portions of the control system during steady state operation. Certain embodiments of the control system utilize pairs of pressure valves, flow control valves, on/offs or a combination of same to control pressure on both sides of shift actuator pistons which provides better control and improved shifts.

Thus it is an object of the present invention to provide a hydraulic control system for a dual clutch automatic transmission.

It is a further object of the present invention to provide a hydraulic control system for a dual clutch transmission having a plurality of spool or logic valves and hydraulic actuators.

It is a still further object of the present invention to provide a hydraulic control system for a dual clutch transmission having a plurality of two position solenoid valves (on/offs), spool valves and hydraulic actuators.

It is a still further object of the present invention to provide a hydraulic control system for a dual clutch transmission having a plurality of flow or pressure control valves, two position solenoid valves, logic or spool valves and hydraulic actuators.

It is a still further object of the present invention to provide a hydraulic control system for a dual clutch transmission comprising two essentially independent hydraulic systems, each associated with a respective transmission countershaft.

It is a still further object of the present invention to provide a hydraulic control system for a dual clutch transmission having a pair of input clutches associated with a pair of concentric input shafts and a pair of countershafts.

DETAILED DESCRIPTION

With reference now toFIG. 1A, an exemplary dual clutch automatic transmission having four shift actuators and incorporating the present invention is illustrated and generally designated by the reference number10. The dual clutch transmission10includes a typically cast, metal housing12which encloses and protects the various components of the transmission10. The housing12includes a variety of apertures, passageways, shoulders and flanges which position and support these components. The transmission10includes an input shaft14which receives motive power from a prime mover (not illustrated) such as an internal combustion gas or Diesel engine or a hybrid or electric power plant and a single or double output shaft16which is coupled to a single or double output assembly18which may include, for example, propshafts, differential assemblies and drive axles. The input shaft14is coupled to and drives an input drive gear20which is in constant mesh with and drives a pair of driven gears, a first driven gear20A and a second driven gear20B. A variety of torque transmitting, rotating devices can be used and are within the scope of this invention. The driven gears20A and20B, in turn, drive a pair of dry input clutches, a first input clutch22A and a second input clutch22B which are mutually exclusively engaged to provide drive torque to a respective pair of layshafts or countershafts, a first countershaft shaft24A and a second countershaft24B. The input clutches22A and22B may also be a pair of concentric input clutches as illustrated inFIG. 1Band described below.

Freely rotatably disposed about each of the countershafts24A and24B are a plurality of helical or spur gears (not illustrated) which are in constant mesh with helical or spur gears which are secured to and rotate with the output shaft16. A first driven gear on the output shaft16meshes with both a drive gear30A on the first countershaft24A and a drive gear30B on the second countershaft24B. A second driven gear on the output shaft16meshes with both a drive gear32A on the first countershaft24A and a drive gear32B on the second countershaft24B. A third driven gear on the output shaft16meshes with both a drive gear34A on the first countershaft24A and a drive gear34B on the second countershaft24B. A fourth driven gear in the output shaft16meshes with both a drive gear36A on the first countershaft24A and an idler gear36B. The idler gear36B, in turn, meshes with a drive gear36C the second countershaft24B to provide torque reversal and thus reverse gear. Other numbers of gear meshes are within the scope of this invention.

Disposed between each adjacent pair of gears on each countershaft24A and24B is a shift actuator and synchronizer clutch assembly. Each shift actuator and synchronizer clutch assembly, in accordance with conventional practice, includes a synchronizer assembly which, when activated, synchronizes the speed of a gear to that of the countershaft and a positive clutch, such as a dog or face clutch, which positively connects or couples the gear to the countershaft. Thus, between the gears30A and32A on the first countershaft24A is a first shift actuator and synchronizer clutch assembly40A having a double, i.e., back-to-back, synchronizer clutch42A which selectively and exclusively synchronizes and engages one of the gears30A and32A to the first countershaft24A. The first synchronizer clutch42A is bi-directionally translated by a first shift rail and fork assembly44A which, in turn, is translated by a first shift actuator assembly46A. The real time linear position of the first synchronizer clutch42A and the first shift rail and fork assembly44A is sensed by a first linear position sensor48A which preferably provides a continuous, i.e., proportional, output to a transmission control module TCM indicating the present position of the first synchronizer clutch42A.

Between the gears34A and36A on the first countershaft24A is a second shift actuator and synchronizer clutch assembly50A having a double, i.e., back-to-back, synchronizer clutch52A which selectively and exclusively synchronizes and engages one of the gears34A and36A to the first countershaft24A. The second synchronizer clutch52A is bi-directionally translated by a second shift rail and fork assembly54A which, in turn, is translated by a second shift actuator assembly56A. The real time linear position of the second synchronizer clutch52A and the second shift rail and fork assembly54A is sensed by a second linear position sensor58A which preferably provides a continuous, i.e., proportional, output to the transmission control module TCM indicating the present position of the second synchronizer clutch52A.

Between the gears30B and32B on the second countershaft24B is a third shift actuator and synchronizer clutch assembly40B having a double, i.e., back-to-back, synchronizer clutch42B which selectively and exclusively synchronizes and engages one of the gears30B and32B to the second countershaft24B. The third synchronizer clutch42B is bi-directionally translated by a third shift rail and fork assembly44B which, in turn, is translated by a third shift actuator assembly46B. The real time linear position of the third synchronizer clutch42B and the third shift rail and fork assembly44B is sensed by a third linear position sensor48B which preferably provides a continuous, i.e., proportional, output to the transmission control module TCM indicating the present position of the third synchronizer clutch42B.

Between the gears34B and36C on the second countershaft24B is a fourth shift actuator and synchronizer clutch assembly50B having a double, i.e., back-to-back, synchronizer clutch52B which selectively and exclusively synchronizes and engages one of the gears34B and36C to the second countershaft24B. The fourth synchronizer clutch52B is bi-directionally translated by a fourth rail and fork assembly54B which, in turn, is translated by a fourth actuator assembly56B. The real time linear position of the fourth synchronizer clutch52B and the fourth shift rail and fork assembly54B is sensed by a fourth linear position sensor58B which preferably provides a continuous, i.e., proportional, output to the transmission control module TCM indicating the present position of the fourth synchronizer clutch52B. It should be appreciated that the linear position sensors48A,48B,58A and58B may be replaced with two or three position switches or open loop control with system characterization.

Additionally, a detent mechanism may be employed with each of the shift assemblies to assist obtaining and maintaining a given gear or speed ratio once it is selected and to assist obtaining and maintaining the synchronizer clutch in neutral, i.e., an unengaged position. Thus, a first detent assembly49A may be operatively associated with the first shift actuator and synchronizer clutch assembly40A. A second detent assembly59A may be operatively associated with the second shift actuator and synchronizer clutch assembly50A. A third detent assembly49B may be operatively associated with the third shift actuator and synchronizer clutch assembly40B and a fourth detent assembly59B may be operatively associated with the fourth shift actuator and synchronizer clutch assembly50B.

With reference toFIG. 1B, a second exemplary dual clutch automatic transmission incorporating the present invention is illustrated and generally designated by the reference number60. The dual clutch transmission60includes a typically cast, metal housing12′ which encloses and protects the various components of the transmission60. The housing12′ includes a variety of apertures, passageways, shoulders and flanges (not illustrated) which position and support the components of the transmission60. The transmission60includes an input shaft14′ which receives motive power from a prime mover (not illustrated) such as an internal combustion gas or Diesel engine or a hybrid or electric power plant and a single or double output shaft16′ which drives a final drive assembly18′ which may include a propshaft, a differential and drive axles. The input shaft14′ is coupled to and drives a clutch housing62. The clutch housing62, in turn, drives a pair of concentrically disposed dry input clutches, a first input clutch64A and a second input clutch64B which are mutually exclusively engaged to provide drive torque to a respective pair of concentric input members, a first or inner input shaft66A and a second or outer hollow input shaft or quill66B.

Secured to and rotating with each of the input members66A and66B are a plurality of helical or spur gears (not illustrated) which are in constant mesh with helical or spur gears which are freely rotatably disposed on a first layshaft or countershaft68A and a parallel, second layshaft or countershaft68B. Adjacent and parallel to the second countershaft is a third layshaft or countershaft68C. A first drive gear meshes with a first driven gear70A on the first countershaft68A. A second drive gear meshes with a second driven gear72A on the first countershaft68A. A third drive gear meshes with a third driven gear74A on the first countershaft68A. A fourth drive gear meshes with a fourth driven gear76A on the first countershaft68A. A fifth driven gear70B on the second countershaft68B meshes with a fifth drive gear70C on the third countershaft68C. The second drive gear also meshes with a sixth driven gear72B on the second countershaft68B which meshes with a seventh driven gear72C on the third countershaft68C. An eighth drive gear meshes with an eighth driven gear74B on the second countershaft68B.

Disposed either adjacent certain single gears or between adjacent pairs of gears on the countershafts68A,68B and68C are synchronizer clutch assemblies. Each synchronizer clutch assembly, in accordance with conventional practice, includes a synchronizer assembly which, when activated, synchronizes the speed of a gear to that of the associated countershaft and a positive clutch, such as a dog or face clutch, which positively connects the gear to the shaft. Thus, between the driven gears70A and72A on the first countershaft68A is a first shift actuator and synchronizer clutch assembly80A having a double, i.e., back-to-back, first synchronizer clutch82A which selectively and exclusively synchronizes and engages one of the gears70A and72A to the first countershaft68A. The first synchronizer clutch82A is bi-directionally translated by a first shift rail and fork assembly84A which, in turn, is translated by a first shift actuator assembly86A. The real time position of the first synchronizer clutch82A and the first shift rail and fork assembly84A is sensed by a first linear position sensor88A which preferably provides a continuous, i.e., proportional, output signal to a transmission control module TCM indicating the position of the first synchronizer clutch82A.

Between the fifth driven gear70B and the sixth driven gear72B on the second countershaft68B is a second shift actuator and synchronizer clutch assembly80B having a single synchronizer clutch82B which synchronizes and couples the driven gears70B and72B together. The second synchronizer clutch82B is bi-directionally translated by a second shift rail and fork assembly84B which, in turn, is translated by a second shift actuator assembly86B. The real time position of the second synchronizer clutch82B and the second shift rail and fork assembly84B is sensed by a second linear position sensor88B which preferably provides a continuous, i.e., proportional, output signal to the transmission control module TCM indicating the position of the second synchronizer clutch82B.

Between the driven gears74A and76A on the first countershaft68A is a third shift actuator and synchronizer clutch assembly90A having a double, i.e., back-to-back, third synchronizer clutch92A which selectively and exclusively synchronizes and engages one of the gears74A and76A to the first countershaft68A. The third synchronizer clutch92A is bi-directionally translated by a third shift rail and fork assembly94A which, in turn, is translated by a third shift actuator assembly96A. The real time position of the third synchronizer clutch92A and the third shift rail and fork assembly94A is sensed by a third linear position sensor98A which preferably provides a continuous, i.e., proportional, output signal to the transmission control module TCM indicating the position of the third synchronizer clutch92A.

Adjacent the eighth driven gear74B on the second countershaft68B is a fourth shift actuator and synchronizer clutch assembly90B having a single synchronizer clutch92B which synchronizes and couples the eighth driven gear74B to the second countershaft68B. The fourth synchronizer clutch92B is bi-directionally translated by a fourth shift rail and fork assembly94B which, in turn, is translated by a fourth shift actuator assembly96B. The real time position of the fourth synchronizer clutch92B and the fourth shift rail and fork assembly94B is sensed by a fourth linear position sensor98B which preferably provides a continuous, i.e., proportional, output signal to the transmission control module TCM indicating the position of the fourth synchronizer clutch92B.

Finally, between the fifth drive gear70C and the seventh driven gear72C on the third countershaft68C is a fifth shift actuator and synchronizer clutch assembly90C having a double, i.e., back-to-back, synchronizer clutch92C which selectively and exclusively synchronizes and engages the driven gear72C to the third countershaft68C or couples the drive gear70C to the driven gear72C. The fifth synchronizer clutch92C is bi-directionally translated by a fifth shift rail and fork assembly94C which, in turn, is translated by a fifth shift actuator assembly96C. The real time position of the fifth synchronizer clutch92C and the fifth shift rail and fork assembly94C is sensed by a fifth linear position sensor98C which preferably provides a continuous, i.e., proportional, output signal to the transmission control module TCM indicating the position of the fifth synchronizer clutch92C. It should be appreciated that the linear position sensors88A,88B,98A,98B and98C may be replaced with other sensors such as two or three position switches or open loop control with system characterization.

Additionally, a detent mechanism may be employed with each of the shift assemblies to assist obtaining and maintaining a gear or speed ratio once it is selected and to assist obtaining and maintaining the synchronizer clutch in neutral, i.e., an unengaged position. Thus, a first detent assembly89A may be operatively associated with the first shift actuator and synchronizer clutch assembly80A. A second detent assembly89B may be operatively associated with the second shift actuator and synchronizer clutch assembly80B. A third detent assembly99A may be operatively associated with the third shift actuator and synchronizer clutch assembly90A. A fourth detent assembly99B may be operatively associated with the fourth shift actuator and synchronizer clutch assembly90B and a fifth detent assembly99C may be operatively associated with the fifth shift actuator and synchronizer clutch assembly90C.

It will be appreciated that the transmission60illustrated and described above is laid out with four forward gears on one countershaft and the remaining (three) forward gears and reverse on two other countershafts. It is thus capable of providing seven forward speeds and reverse. Similar configurations, all deemed to be within the scope of this invention may, for example, include six forward speeds (or gears) and one or two reverse speeds (or gears) or five forward speeds and one or two reverse speeds.

It should be understood that while the present invention is directed to hydraulic control systems for dual clutch transmissions, such systems are typically controlled by sensor signals and memory, software and one or more microprocessors contained in a transmission control module TCM. Thus, the transmission control module TCM includes a plurality of inputs which receive data from, for example, the linear position sensors, the pressure sensor, speed sensors and temperature sensors and a plurality of outputs which control and modulate, for example, the positions of the clutches, shift rails and logic solenoid valves.

Just, as noted above, the transmission may include various numbers of forward and reverse speeds or gear ratios, various embodiments of the transmission may include four shift actuators and shift rails or five shift actuators and shift rails and single or double synchronizer clutch assemblies as described herein. Embodiments having four shift rails include four double synchronizer clutch assemblies, typically disposed in pairs on two countershafts, as illustrated in the transmission10inFIG. 1A. Embodiments having five shift rails include two single and three double synchronizer clutch assemblies disposed on three countershafts, as illustrated in the transmission60inFIG. 1B. Similarly, it should be appreciated that variations in actuator piston design and sensor configuration may result from performance requirements and cost constraints but are considered to be within the purview of the present invention.

Referring now toFIGS. 1A,2A and2B, a first embodiment of a hydraulic control system for the dual clutch automatic transmission10described above is illustrated and designated by the reference number1400. The hydraulic control system1400includes a sump102to which hydraulic fluid returns and collects from various components and regions of the automatic transmission10. A suction line104which may include a filter106communicates with the inlet port108of an engine driven or electric pump110which may be, for example, a gear pump, a vane pump, a gerotor pump or other positive displacement pump. An outlet port112of the pump110provides hydraulic fluid under pressure in a supply line114to a spring biased blow-off safety valve116and to a pressure side filter118which is disposed in parallel with a spring biased check valve120. The safety valve116is set at a relatively high predetermined pressure and if the pressure in the supply line114exceeds this pressure, the safety valve116opens momentarily to relieve and reduce it. If pressure ahead of the filter118rises to a predetermined differential pressure, indicating a partial blockage or flow restriction when cold of the filter118and the possibility that insufficient hydraulic fluid may be provided in an outlet line122to the remainder of the control system1400, the check valve120opens to allow hydraulic fluid to bypass the filter118. A second check valve124, in the outlet line122, is configured to maintain hydraulic pressure in a main supply line126and to prevent backflow through the pump110. The main supply line126supplies pressurized hydraulic fluid to an accumulator130having a piston132and a biasing compression spring134. The accumulator130may be one of many other designs including a gas filled piston accumulator.

The accumulator130stores pressurized hydraulic fluid and supplies it to the main supply line126, to a main or system pressure sensor136and to the other components of the control system1400thereby eliminating the need for an engine driven pump or for the electric pump110to run continuously. The main pressure sensor136reads the delivered hydraulic system pressure in real time and provides this data to the transmission control module TCM. It should be appreciated that all of the other embodiments of the hydraulic control system according to the present invention preferably include the same hydraulic supply, filtration and control components just described. Accordingly, these components will be only briefly described in connection with the subsequent figures and embodiments, it being understood that the above description may be referenced to provide details of these components.

The main supply line126communicates with a plurality of smaller supply lines. The first supply line126A communicates with an inlet port140A of a first electric pressure control solenoid valve140. The first pressure control solenoid valve140also includes an outlet port140B that communicates with the inlet port140A when the first control valve140is activated or energized and an exhaust port140C that communicates with the outlet port140B when the first pressure control valve140is de-energized. The exhaust port140C communicates with the sump102. The outlet port140B of the pressure control solenoid valve140communicates with a first line1420that communicates with the first electric pressure or flow clutch control solenoid valve154. The first clutch control solenoid valve154also includes an outlet port154B and an exhaust port154C which communicates with the sump102. It should be understood that the various exhaust ports may be connected directly to the sump102or, if desired, they may be connected to a common exhaust backfill circuit (not illustrated).

When the first clutch control solenoid valve154is energized, pressurized hydraulic fluid is provided through a flow restricting orifice156in the line158to the first clutch piston and cylinder assembly160. Slidably disposed within a cylinder162is a single acting piston164which translates to the right inFIG. 2Aunder hydraulic pressure to engage the first input clutch22A. To disengage the first input clutch22A, hydraulic fluid is exhausted through the first clutch control solenoid154. Disposed in a hydraulic line extending between the first line1420and the line158is a first clutch pressure limit control valve166. If pressure within the first clutch piston and cylinder assembly160exceeds a predetermined pressure determined by the first pressure control valve140, the first clutch pressure limit valve166opens to relieve and reduce the pressure.

It should be understood that the first clutch pressure limit valve166(as well as the second clutch pressure limit valve216described below) may be eliminated depending upon various requirements of the control system1400. It should also be understood that the incorporation or omission of flow control orifices such as the orifice156in all the hydraulic lines of the various embodiments is within the scope this invention. The locations and sizes of the flow control orifices are based on operational, software and algorithm requirements.

The second supply line126B communicates with an inlet port190A of a second electric pressure control solenoid valve190. The second pressure control solenoid valve190also includes an outlet port190B that communicates with the inlet port190A when the first control valve190is activated or energized and an exhaust port190C that communicates with the outlet port190B when the second pressure control valve190is de-energized. The exhaust port190C communicates with the sump102. The outlet port190B communicates with a second line1422which communicates with an inlet port204A of a second electric pressure or flow clutch control solenoid valve204. The second clutch control solenoid valve204also includes an outlet port204B and an exhaust port204C which communicates with the sump102.

When the clutch control solenoid valve204is energized, pressurized hydraulic fluid is provided through an orifice206in a line208to the second clutch piston and cylinder assembly210. Slidably disposed within a cylinder212is a single acting piston214which translates to the right inFIG. 2Aunder hydraulic pressure to engage the second input clutch22B, illustrated inFIG. 1Aand vice versa. Disposed in a hydraulic line extending between the second line1422and the line208is a second clutch pressure limit control valve216. If pressure within the second clutch piston and cylinder assembly210exceeds a predetermined pressure determined by the second pressure control valve190, the second clutch pressure limit valve216opens to relieve and reduce the pressure.

The first embodiment1400of the hydraulic control system also includes a third main supply line126C which communicates with an inlet port1030A of a first electric pressure or flow control solenoid valve1030. An exhaust port1030C communicates with the sump102. A fourth supply line126D communicates with an inlet port1430A of a second electric pressure or flow control solenoid valve1430. An exhaust port1430C communicates with the sump102. A first line1432communicates between an outlet port1030B of the first electric pressure or flow control solenoid valve1030and a first inlet port1040A of a first spool or logic valve1040and a second line1434communicates between an outlet port1430B of the second electric pressure or flow control solenoid valve1430and a second inlet port1040B of the first spool or logic valve1040.

The first spool or logic valve1040includes a control port1040C, three exhaust ports1040D,1040E, and1040F and four outlet ports1040G,1040H,1040I and1040J. The fourth supply line126D also communicates with an inlet port1042A of a first two position (on-off) solenoid valve1042. An outlet port1042B of the first two position solenoid valve1042communicates with the control port1040C at the end of the first logic valve1040. When the two position solenoid valve1042is activated or energized, pressurized hydraulic fluid is supplied to the control port1040C of the first logic valve1040, translating the spool to the left as illustrated inFIG. 2B; when the two position solenoid valve1042is inactive or de-energized, hydraulic fluid is exhausted from the first logic valve1040, through the outlet port1042B and out an exhaust port1042C to the sump102, allowing the spool to translate to the right. It should be understood that the devices which translate the spools of the logic valves are not limited to hydraulic on/off valves. For example, the armature of a solenoid may act directly on the logic valve spool. Additionally, a single on/off valve may be multiplexed to actuate multiple logic valves simultaneously. It should also be understood that modifications may be made to the logic valves and ports without changing their function in the control system1400.

The first spool or logic control valve1040includes a first outlet port1040G which communicates with a first inlet port1060A of a second spool or logic valve1060through a line1046and a third outlet port1040H which communicates with a second inlet port1060B of the second spool or logic valve1060through a line1048. A fifth supply line126E connects to an inlet port1062A of a second two position (on-off) solenoid valve1062. An outlet port1062B of the second two position solenoid valve1062communicates with a control port1060C at the end of the second logic valve1060. It should be appreciated that instead of feeding supply lines126C,126D and126E directly from the accumulator130, they can be fed by a check valve that multiplexes between the outputs of the electric pressure control valves140B and190B in a manner similar to the control system1500illustrated inFIG. 3B.

When the second two position solenoid valve1062is activated or energized, pressurized hydraulic fluid is supplied to control port1060C of the second logic valve1060, translating the spool to the left as illustrated inFIG. 2B; when the two position solenoid valve1062is inactive or de-energized, hydraulic fluid is exhausted from the second logic valve1060, through the outlet port1062B and out an exhaust port1062C to the sump102, allowing the spool to translate to the right. Three exhaust ports1060D,1060E and1060F alternate with the two inlet ports1060A and1060B and, although not indicated for reasons of clarity, communicate with the sump102. The hydraulic lines connecting the logic valves and shift actuators may be in any order or arrangement as long as system operation and functionality is maintained.

A first outlet port1060G of the second logic valve1060communicates through a line1064with a first port1068A of a cylinder1068of a first shift actuator piston and cylinder assembly1070. The first shift actuator piston and cylinder assembly1070includes a piston1072that is coupled to and drives, for example, the first shift rail and fork assembly44A and the first synchronizer clutch assembly42A. The cylinder1068also includes a second port1068B which communicates through a line1073with a third outlet port1060H of the second logic valve1060. A second outlet port10601of the second logic valve1060communicates through a line1074with a first port1078A of a cylinder1078of a second shift actuator piston and cylinder assembly1080. The second shift actuator piston and cylinder assembly1080includes a piston1082that is coupled to and drives, for example, the second shift rail and fork assembly54A and the second synchronizer clutch assembly52A. The cylinder1078also includes a second port1078B which communicates through a line1083with a fourth outlet port1060J of the second logic valve1060. It should be appreciated that the various shift actuator piston and cylinder assemblies may incorporate various designs and geometry, for example, two area pistons and positive neutral, three area pistons, all of which are considered to be within the scope of the present invention. Furthermore, it should be appreciated that a determination of which synchronizer clutch is associated with which shift actuator is dependent upon packaging, failure modes and other design and engineering criteria and that, accordingly, alternate and interchanged configurations of this and the other embodiments are considered to be within the scope of this invention.

Returning to the first spool or logic control valve1040, it includes a second outlet port1040I which communicates with a first inlet port1090A of a third spool or logic valve1090through a line1052and a fourth outlet port1040J which communicates with a second inlet port1090B of the third spool or logic valve1090through a line1054. The fourth supply line126D connects to an inlet port1092A of a third two position (on-off) solenoid valve1092. An outlet port1092B of the second two position solenoid valve1092communicates with a control port1090C at the end of the third logic valve1090. Alternatively, the logic valve1090can be actuated by the second two position (on-off) solenoid valve102if desired.

When the third two position solenoid valve1092is activated or energized, pressurized hydraulic fluid is supplied to the control port1090C of the third logic valve1090, translating the spool to the left as illustrated inFIG. 2B. When the third two position (on-off) solenoid valve1092is de-energized, hydraulic fluid is exhausted from the third logic valve1090, through the outlet port1092B of the third two position (on-off) solenoid valve1092and out an exhaust port1092C to the sump102, allowing the spool to translate to the right. Three exhaust ports1090D,1090E and1090F alternate with the two inlet ports1090A and1090B and, although not indicated for reasons of clarity, communicate with the sump102.

A first outlet port1090G of the third logic valve1090communicates through a line1094with a first port1098A of a cylinder1098of a third shift actuator piston and cylinder assembly1100. The third shift actuator piston and cylinder assembly1100includes a piston1102that is coupled to and drives, for example, the third shift rail and fork assembly44B and the third synchronizer clutch assembly42B. The cylinder1098also includes a second port1098B which communicates through a line1103with a third outlet port1090H of the third logic valve1090. A second outlet port1090I of the third logic valve1090communicates through a line1104with a first port1108A of a cylinder1108of a fourth shift actuator piston and cylinder assembly1110. The fourth shift actuator piston and cylinder assembly1110includes a piston1112that is coupled to and drives, for example, the fourth shift rail and fork assembly54B and the fourth synchronizer clutch assembly52B. The cylinder1108also includes a second port1108B which communicates through a line1113with a fourth outlet port1090J of the third logic valve1090.

Operation of the first embodiment of the hydraulic control system1400essentially involves the selection of a desired gear ratio in the transmission10by the transmission control module TCM, selection and activation of the pressure control solenoid valves140and190to provide pressurized hydraulic fluid to the input clutch hydraulic circuits, activation of the pressure or flow control solenoid valves1030and1430to provide controlled flow and pressure of hydraulic fluid to the logic valves1040,1060and1090and activation of the two position (on-off) solenoid valves1042,1062and1092to position the logic valve spools to direct pressurized hydraulic fluid flow to the correct sides of the piston and cylinder assemblies1070,1080,1100and1110to translate the shift rails44A,44B,54A and54B to engage the desired gear. Once this has occurred, the input clutch22A or22B associated with the countershaft24A or24B of the selected gear is engaged by activation of one of the piston and cylinder assemblies160or210.

A convenient example of operation may be presented by describing same with the spools of the logic valves1040,1060and1090in the positions illustrated inFIG. 2B. Activation of the first pressure or flow control solenoid valve1030provides hydraulic fluid to the line1432, through the first logic valve1040, through the line1046to the second logic valve1060and through the line1064to the port1068A in the first piston and cylinder assembly1070. The piston1072and the first shift rail44A will then translate to the right and engage, for example, seventh gear. The shift is completed by engaging the appropriate input clutch. If, on the other hand, the second pressure or flow control solenoid valve1430is activated, hydraulic fluid flow occurs through the lines1434,1048and1073, either returning the first shift rail44A to neutral or moving the shift rail44A all the way to the left to the position illustrated inFIG. 2Bto engage, for example, fifth gear. The choice of the center (neutral) or left position is commanded by the transmission control module TCM with linear position information from, for example, the first linear position sensor48A illustrated inFIG. 1A. A similar pattern of valve activation and logic valve spool translation provides the seven forward and reverse gears of the transmission10. For example, if the first two position solenoid valve1042is energized, the spool of the first logic valve1040translates to the left, providing all hydraulic fluid flows to the lines1052and1054and the third logic valve1090associated with the third and fourth piston and cylinder assemblies1100and1110.

Referring now toFIGS. 1B,3A,3B and3C, a second embodiment of a hydraulic control system according to the present invention is illustrated and generally designated by the reference number1500. The second embodiment1500, while sharing many components with the first embodiment1000, is intended for use with the seven speed transmission60illustrated inFIG. 1Bhaving five shift rails and shift actuators. The second embodiment1500of the hydraulic control system, as stated, includes, in common with the other embodiments, the pump110, preferably electric, the filters106and118, the accumulator130and the other components of the hydraulic fluid supply and thus they will not be further described.

The second embodiment1500of the hydraulic control system includes the main supply line126which bifurcates into a first main supply line126A and a second main supply line126B. The first main supply line126A communicates with the inlet port140A of the first pressure control solenoid valve140and the second main supply line126B communicates with the inlet port190A of the second pressure control solenoid valve190. The outlet port140B of the first pressure control solenoid valve140communicates with the first manifold1002and the outlet port190B of the second pressure control solenoid valve190communicates with the second manifold1004.

Similarly, the second embodiment1500includes the components associated with activation of the first clutch64A, such as the first electric pressure or flow clutch control solenoid valve154which receives hydraulic fluid from a first branch1002A of the first manifold1002, the orifice156, the first clutch piston and cylinder assembly160and the first clutch pressure limit control valve166which communicates with the second branch1002B of the first manifold1002as well as the components associated with activation of the second clutch64B, such as the second electric pressure or flow clutch control solenoid valve204which receives hydraulic fluid from the second branch1004B of the second manifold1004, the orifice206, the second clutch piston and cylinder assembly210and the second clutch pressure limit control valve216which communicates with the third branch1004C of the second manifold1004. It should be noted that the first and the second pressure limit control valves166and212may be eliminated depending upon the requirements of the control system1500.

Disposed between the first manifold1002and the second manifold1004is a ball check valve1510. The ball check valve1510includes a first inlet port1512connected to the first manifold1002, a second inlet port1514connected to the second manifold1004and an outlet port1516connected to a branching supply line1520. The ball check valve1510closes off the inlet port delivering the lower hydraulic pressure and provides communication between the inlet port having or delivering the higher hydraulic pressure and the outlet port1516and the branching supply line1520. Cutting off the flow allows either pressure control solenoid140or190to feed the solenoid valves used for gear actuation and thus allows either pressure control solenoid140or190to be shut off or operate at lower line pressure while still maintaining the selection of all gear ratios at any time. This configuration also allows the gear actuators to be fed with a lower pressure than the accumulator130and will reduce overall system leakage and provide additional failure mode protection.

A first branch1520A of the branching supply line1520communicates with the inlet port1030A of the first electric pressure or flow control solenoid valve1030. The outlet port1030B of the first pressure or flow control solenoid valve1030is connected by the line1432with the first inlet port1040A of the first spool or logic control valve1040. The exhaust port1030C communicates with the sump102. The second main supply line1520B communicates with the inlet port1430A of the second electric pressure or flow control solenoid valve1430. The second line1434communicates between the outlet port1430B of the second electric pressure or flow control solenoid valve1430and the second inlet port1040B of the first spool or logic valve1040. The exhaust port1430C communicates with the sump102. As noted above, it should be understood that the exhaust ports throughout the system may be connected directly to the sump102or may be connected to a common exhaust backfill circuit (not illustrated).

The first spool or logic valve1040includes the control port1040C which is selectively supplied pressurized hydraulic fluid from the first two position solenoid (on-off) valve1042which, in turn, is supplied with hydraulic fluid from a third branch1520C of the manifold1520. The first spool or logic valve1040also includes the three exhaust ports1040D,1040E, and1040F disposed between and alternating with the inlet ports1040A and1040B.

Similar to the first embodiment1400, the second embodiment1500includes the hydraulic lines1046and1048which communicate between the first and the third outlet ports1040G and1040H, respectively, of the first logic valve1040and the first and second input ports1060A and1060B, respectively, of the second spool or logic valve1060. The hydraulic lines1052and1054connect the fourth and the second outlet ports1040J and1040I of the first logic valve1040to the first and second inlet ports1090A and1090B of the third spool or logic valve1090. Likewise, the second spool or logic valve1060includes the control port1060C, the second two position (on-off) solenoid valve1062and the exhaust ports1060D,1060E, and1060F. The inlet port1062A of the second two position solenoid valve1062receives hydraulic fluid through a third branch1520C of the manifold1520. The hydraulic line1064and the line1073communicate with opposite ends of the first, preferably dual area piston and cylinder assembly1070which translates the first shift rail and fork assembly84A and the hydraulic line1074and the line1083communicate with opposite ends of the second piston and cylinder assembly1080which translates the second shift rail and fork assembly84B.

Similarly, the third spool or logic valve1090includes the control port1090C, the third two-position (on-off) solenoid valve1092and the exhaust ports1090D,1090E, and1090F. The inlet port1092A of the third two position solenoid valve1092receives hydraulic fluid through a fourth branch1520D of the manifold1520. The hydraulic lines1094and1103communicate between the first and the third outlet ports1090G and1090H, respectively, of the third logic valve1090and opposite ends of a third, preferably dual area piston and cylinder assembly1100which translates the third shift rail and fork assembly94A.

The hydraulic line1104connected to the second outlet port1090I communicates with a first inlet port1530A of a fourth spool or logic valve1530and the line1113connected to the fourth outlet port1090J communicates with a second inlet port1530B of the fourth logic valve1530. The right end of the fourth logic valve1530is selectively supplied with pressurized hydraulic fluid from the output of the second two position (on-off) solenoid valve1062in a line1532. Thus, the spool of the fourth logic valve1530translates in unison with the spool of the second logic valve1060. When the second two position solenoid valve1062is energized, both spools translate to the left as viewed inFIGS. 3B and 3C. When the second two position solenoid valve1062is de-energized, both spools translate to the right. It should be apparent that actuation of the fourth logic valve1530may also be controlled by an fourth two position (on-off) solenoid valve (not illustrated) for better failure modes. This multiplexing of the on-off is possible if the logic valves being controlled are used for controlling a synchronizer clutch in the opposite state of the upstream logic valve1040.

The fourth logic valve1530includes a first outlet port1530G which communicates through a line1536to one end of a fourth piston and cylinder assembly1540having a piston1542which is coupled to the fourth shift rail and fork assembly94B. The other end of the fourth piston and cylinder assembly1542communicates through a line1544to a third outlet port1530H. Similarly, a second outlet port15301communicates through a line1546to one end of a fifth, preferably dual area piston and cylinder assembly1550having a piston1552which is coupled to the fifth shift rail and fork assembly94C. The other end of the fifth piston and cylinder assembly1550communicates through a line1554to a fourth outlet port1530J.

Referring now toFIGS. 1B,4A,4B and4C, a third embodiment of a hydraulic control system according to the present invention is illustrated and generally designated by the reference number1600. The third embodiment1600of the hydraulic control system, as stated, includes, in common with the other embodiments, the pump110, the filters106and118, the accumulator130and the other components of the hydraulic fluid supply and thus they will not be further described.

The third embodiment1600is essentially the same as the second embodiment1500of the hydraulic control system. The primary difference is the incorporation of spool or logic valves having integrated on-off solenoid operators or solenoids in which the solenoid pendal or plunger acts directly on the logic valve spool instead of controlling a flow of hydraulic fluid into a control port at one end of the spool or logic valve. This reduces the hydraulic circuits and packaging, while potentially reducing leakage. The logic valves themselves are also slightly different and include a central, common exhaust and can be hydraulically actuated. However, there are other logic valves that will achieve the same function and all are deemed to be within the scope of the present invention. Thus, the third embodiment1600includes the main supply line126which bifurcates into the first main supply line126A and the second main supply line126B. The first main supply line126A communicates with the inlet port140A of the first pressure control solenoid valve140and the second main supply line126B communicates with the inlet port190A of the second pressure control solenoid valve190. The outlet port140B of the first pressure control solenoid valve140communicates with the first manifold1002and the outlet port190B of the second pressure control solenoid valve190communicates with the second manifold1004.

Similarly, the third embodiment1600includes the components associated with activation of the first clutch64A, such as the first electric pressure or flow clutch control solenoid valve154which receives hydraulic fluid from the first branch1002A of the first manifold1002, the first clutch piston and cylinder assembly160and the first clutch pressure limit control valve166which communicates with the second branch1002B of the first manifold1002as well as the components associated with activation of the second clutch64B, such as the second electric pressure or flow clutch control solenoid valve204which receives hydraulic fluid from the first branch1004B′ of the second manifold1004, the second clutch piston and cylinder assembly210and the second clutch pressure limit control valve216which communicates with the second branch1004C′ of the second manifold1004.

Disposed between the first manifold1002and the second manifold1004is the check valve1510. The check valve1510feeds the higher pressure hydraulic fluid into the branching supply line1520, as noted above. This permits relaxation of hydraulic fluid pressure in part of the transmission60, while allowing gear ratio selection at any time, lowers leakage by feeding the gear actuator controls with lower pressure hydraulic fluid compared to that provided by the accumulator130and provides additional failure mode protection. The first branch1520A of the branching supply line1520communicates with the inlet port1030A of the first electric pressure or flow control solenoid valve1030. An outlet port1030B of the first pressure or flow control solenoid valve1030is connected by the line1432with the first inlet port1040A of the first spool or logic control valve1040. The exhaust port1030C communicates with the sump102. The second main supply line1520B communicates with the inlet port1430A of the second electric pressure or flow control solenoid valve1430. The second line1434communicates between the outlet port1430B of the second electric pressure or flow control solenoid valve1430and the second inlet port1040B of the first spool or logic valve1040. The exhaust port1430C communicates with the sump102. Similar to the previous embodiments, the exhaust ports may be connected directly to the sump102or, if desired, they may be connected to a common exhaust backfill circuit (not illustrated).

The right end of the spool of the first spool or logic valve1040is directly acted upon by a plunger or pendal of the first two position (on-off) solenoid1042. The first two position solenoid1042associated with the first logic valve1040may be replaced by a single, cartridge style, direct acting solenoid similar to a pressure control solenoid. The first spool or logic valve1040also includes a common exhaust port1040D disposed at an end opposite the on-off solenoid1042.

Similar to the second embodiment1500, the third embodiment1600also includes the hydraulic lines1046and1048to the first and second input ports1060A and1060B, respectively, of the second spool or logic valve1060and the hydraulic lines1052and1054to the first and second inlet ports1090A and1090B of the third spool or logic valve1090.

Likewise, the second spool or logic valve1060includes the integrated second two position (on-off) solenoid1062and the common exhaust port1060D. The second two position solenoid valve1062associated with the second logic valve1060may be replaced with a single, cartridge style, direct acting solenoid similar to a pressure control solenoid. The hydraulic lines1064and1073connected to the first outlet port1060G and the third outlet port1060H, respectively, communicate with opposite ends of the first, preferably dual area piston and cylinder assembly1070which translates the first shift rail and fork assembly84A to engage, for example, second and six gears. The lines1074and1083connected to the second outlet port10601and the fourth outlet port1060J, respectively, communicate with opposite ends of the second piston and cylinder assembly1080which translates the second shift rail and fork assembly84B to engage, for example, fourth gear.

Similarly, the third spool or logic valve1090includes the third two position (on-off) solenoid1092and the common exhaust port1090D. The third two position solenoid1092associated with the third logic valve1090may be replaced with a single, cartridge style, direct acting solenoid similar to a pressure control solenoid. The hydraulic lines1094and1103connected to the first outlet port1090G and the third outlet port1090H, respectively, communicate with opposite ends of the third, preferably dual area piston and cylinder assembly1100which translates the third shift rail and fork assembly94A to engage, for example, fifth and seventh gears.

The hydraulic lines1104and1113connected to the second outlet port1090I and the fourth outlet port1090J, respectively, communicate with the first inlet port1530A and the second inlet port1530B, respectively, of the fourth spool or logic valve1530. A fourth two position (on-off) solenoid1532is directly coupled to the spool of the fourth logic valve1530and bi-directionally translates it. The fourth two position (on-off) solenoid1532associated with the fourth logic valve1530may be replaced with a single, cartridge style, direct acting solenoid similar to a pressure control solenoid. The fourth spool or logic valve1530includes a common exhaust port1530D.

The fourth logic valve1530includes the first outlet port1530G which communicates through the line1536to one end of the fourth piston and cylinder assembly1540having a piston1542which is coupled to the fourth shift rail and fork assembly94B which engages, for example, third gear. The other end of the piston and cylinder assembly1540communicates through the line1544to the third outlet port1530H. Similarly, the second outlet port15301communicates through the line1546to one end of a fifth, preferably dual area piston and cylinder assembly1550having a piston1552which is coupled to the fifth shift rail and fork assembly94C which engages, for example, first and reverse gears. The other end of the fifth piston and cylinder assembly1550communicates through a line1554to a fourth outlet port1530J.

Referring now toFIGS. 1B,5A,5B and5C, a fourth embodiment of a hydraulic control system according to the present invention is illustrated and generally designated by the reference number1900. The fourth embodiment1900of the hydraulic control system, as stated, includes, in common with the other embodiments, the electric pump110, the filters106and118, the accumulator130and the other components of the hydraulic fluid supply and thus they will not be further described.

The fourth embodiment1900is also similar to the second embodiment1500illustrated inFIGS. 3A,3B and3C except that the gear actuator control solenoids and the two position control valves are fed directly from the output of the accumulator130rather than by either of the pressure control valves140or190through the check valve1510. The fourth embodiment1900is also similar to the first embodiment1400illustrated inFIGS. 2A and 2Bwith regard to the clutch control circuitry. As such, the main supply line126communicates with a manifold1902which branches into a plurality of smaller main supply lines. The first branch1902A communicates with the inlet port140A of the first electric pressure control solenoid valve140which includes an outlet port140B that communicates with the inlet port140A when the first control valve140is energized. The exhaust port140C communicates with the outlet port140B and the sump102when the first pressure control valve140is de-energized. The outlet port140B is connected to the first line1420which communicates with the inlet port154A of the first electric pressure or flow clutch control solenoid valve154. The first clutch control solenoid valve154also includes the inlet port154A, the outlet port154B and the exhaust port154C which communicates with the sump102or an exhaust backfill circuit.

When the clutch control solenoid valve154is energized, pressurized hydraulic fluid is provided through the orifice156in the line158to the first clutch piston and cylinder assembly160. Slidably disposed within the cylinder162is a single acting piston164which translates to the right inFIG. 5Aunder hydraulic pressure to engage the first input clutch64A and vice versa.

The fourth branch1902D of the manifold1902communicates with the inlet port190A of the second electric pressure control solenoid valve190. The second pressure control solenoid valve190also includes the outlet port190B that communicates with the inlet port190A when the first control valve190is energized and the exhaust port140C that communicates with the outlet port190B and the sump102when the second pressure control valve190is de-energized. The outlet port190B connects to the second line1422which communicates with the inlet port204A of the second electric pressure or flow clutch control solenoid valve204. The second clutch control solenoid valve204also includes the outlet port204B and the exhaust port204C which communicates with the sump102.

When the clutch control solenoid valve204is activated or energized, pressurized hydraulic fluid is provided through the orifice206in the line208to the second clutch piston and cylinder assembly210. Slidably disposed within the cylinder212is the single acting piston214which translates to the right inFIG. 5Aunder hydraulic pressure to engage the second input clutch64B and vice versa.

As noted, the main supply line126communicates with the branching manifold1902. The manifold1902has a second branch1902B which supplies hydraulic fluid to the inlet port1030A of the first pressure or flow control solenoid valve1030. The branching manifold includes a third branch1902C which communicates with the inlet port1430A of the second pressure or flow control solenoid valve1430, the inlet port1042A of the first two position (on-off) solenoid valve1042, the inlet port1062A of the second two position (on-off) solenoid valve1062and the inlet port1092A of the third two position (on-off) solenoid valve1092.

An outlet port1030B of the first pressure or flow control solenoid valve1030is connected by the line1432with the first inlet port1040A of the first spool or logic control valve1040. The exhaust port1030C communicates with the sump102. The line1434communicates between the outlet port1430B of the second electric pressure or flow control solenoid valve1430and the second inlet port1040B of the first spool or logic valve1040. The exhaust port1430C communicates with the sump102.

The right end of the first logic valve1040is selectively supplied pressurized hydraulic fluid from the first two position (on-off) solenoid valve1042which, in turn, is supplied with hydraulic fluid from the third branch1902C of the manifold1902. The first logic valve1040also includes three exhaust ports1040D,1040E, and1040F disposed between and alternating with the inlet ports1040A and1040B.

The fourth embodiment1900also includes the hydraulic lines1046and1048connected to the first outlet port1040G and the third outlet port1040H, respectively, which communicate with the first and second input ports1060A and10608, respectively, of the second spool or logic valve1060and the hydraulic lines1052and1054connected to the fourth outlet port1040J and the second outlet port1040I, respectively, which communicate with to the first and second inlet ports1090A and1090B of the third spool or logic valve1090.

Likewise, the second logic valve1060includes the second two position (on-off) solenoid valve1062and the exhaust ports1060D,1060E, and1060F. The inlet port1062A of the second two position solenoid valve1062receives hydraulic fluid through the third branch1902C of the manifold1902. The hydraulic lines1064and1073connected to the first outlet port1060G and the third outlet port1060H, respectively, of the second logic valve1060communicate with the ports1068A and1068B at opposite ends of the first, preferably dual area piston and cylinder assembly1070which translates the first shift rail and fork assembly84A. The hydraulic lines1074and1083connected to the second outlet port10601and the fourth outlet port1060J, respectively, communicate with the ports1078A and1078B at opposite ends of the second piston and cylinder assembly1080which translates the second shift rail and fork assembly84B.

Similarly, the third spool or logic valve1090includes the control port1090C and the three exhaust ports1090D,1090E, and1090F. The inlet port1092A of the third two position (on-off) solenoid valve1092receives hydraulic fluid through the third branch1902C of the manifold1902and it selectively supplies hydraulic fluid through an outlet port1092B to the control port1090C of the third logic valve1090. The lines1094and1103connected to the first outlet port1090G and the third outlet port1090H, respectively, of the third logic valve1090communicate with the ports1098A and1098B at opposite ends of the third, preferably dual area piston and cylinder assembly1100which translates the third shift rail and fork assembly94A.

The hydraulic lines1104and1113connected to the second outlet port1090I and the fourth outlet port1090J, respectively, of the third logic valve1090communicate with the first inlet port1530A and the second inlet port1530B, respectively, of the fourth spool or logic valve1530. The fourth logic valve1530includes a control port1530C which selectively receives hydraulic fluid from the outlet port1062B of the second two position (on-off) solenoid valve1062through the line1532. The spool of the second logic valve1060and the spool of the fourth logic valve1530thus translate in unison. When the second two position solenoid valve1062is energized, both spools translate to the left as viewed inFIGS. 5B and 5C. When the second two position solenoid valve1062is de-energized, both spools translate to the right. The fourth logic valve1530also includes three exhaust ports1530D,1530E and1530F which are interleaved with the inlet ports1530A and1530B.

The fourth logic valve1530includes the first outlet port1530G which communicates through the line1536to the port1538A at one end of the fourth piston and cylinder assembly1540having a piston1542which is coupled to the fourth shift rail and fork assembly94B. The other end of the fourth piston and cylinder assembly1540communicates through the port1538B and the line1544to the third outlet port1530H. Similarly, the second outlet port15301communicates through the line1546to the port1548A at one end of the fifth, preferably dual area piston and cylinder assembly1550having the piston1552which is coupled to the fifth shift rail and fork assembly94C. The other end of the fifth piston and cylinder assembly1550communicates through the port1548B and the line1554to the fourth outlet port1530J.

It will be appreciated that the hydraulic control systems according to various embodiments of the present invention achieve significant improvements in reduced energy consumption and shift performance not only because of the incorporation of the dedicated electric pump and accumulator but also because of the use of pressure and flow control solenoid valves which allow the majority of the hydraulic system components to be turned off in normal, steady-state, operation. Additionally, these solenoid valves and the linear position sensors on each piston and cylinder shift actuator assembly which provide real time data to the transmission control module regarding the instantaneous positions of the actuators, shift rails and clutches, achieve gear selection and clutch operation that is rapid, positive and efficient without overshoot and wasted energy.

Similarly, the configurations of the various embodiments and the position feedback provided by the linear position sensors permits and facilitates rapid gear sequencing and improved, i.e., reduced, shift times.

Finally, the separation of hydraulic fluid supply and control functions into two regions or sections corresponding to the odd and even gear selecting portions of the transmissions, reduces the likelihood of inaccurate or multiple gear selection and further improves efficiency by permitting shutting down the non-active region or section of the transmission during certain operating situations such as extended operation in the highest gear.