STANDARD STRATEGY FOR SWITCHING OFF HYDRAULICS

Abstract

A hydraulic control system for a transmission having an input member and an output member (102) operable in at least one forward speed ratio between the output member (104) and the input member (102) and in at least one reverse speed ratio between the output member (104) and the input member (102), comprising: a standard hydraulic control system (260) comprising: a first valve assembly (262) having a first control valve (268) controlled by a first solenoid (266), and a second valve assembly (264) having a second control valve (272) controlled by a second magnet (270), wherein the hydraulic default control system (260) is configured to shift the transmission into a first default speed ratio when the transmission is operating in a first of the at least one forward speed ratio and experiencing a default condition, and to shift the transmission into a second default speed ratio when the transmission is operating in a reverse speed ratio and experiencing the default condition, wherein the first control valve (268) comprises a first spool valve (278) and the second control valve comprises a second spool valve (272) configured to stroke faster than the first spool valve (278).

Description

AREA OF REVELATION

[0001] The present disclosure relates to a hydraulic control strategy for a hydraulic control system of a transmission, and more particularly to a default state strategy for a hydraulic control system of a multi-speed transmission. BACKGROUND OF REVELATION

[0002] Known multi-speed planetary gear sets utilize a plurality of interconnecting members and selective clutches to achieve a plurality of forward and reverse speed ratios between at least one input member and at least one output member connected to the multi-speed transmission. The selective clutches are selectively engaged to establish each of the plurality of forward and reverse speed ratios. The engagement of the selective clutches may be controlled by a hydraulic control system. The hydraulic control system may include a default control subsystem that controls the engagement of the selective clutches during a default condition. SUMMARY OF REVELATION

[0003] The present disclosure relates to a hydraulic control strategy for a hydraulic control system of a transmission. In an exemplary embodiment of the present disclosure, a hydraulic control system for a transmission having an input member and an output member is disclosed, operable in at least one forward speed ratio between the output member and the input member and in at least one reverse speed ratio between the output member and the input member. The hydraulic control system includes a standard hydraulic control system including a first valve assembly having a first control valve controlled by a first solenoid and a second valve assembly having a second control valve controlled by a second solenoid.The hydraulic default control system is configured to shift the transmission into a first default speed ratio when the transmission is operating in a first of the at least one forward speed ratio and a default condition occurs, and to shift the transmission into a second of the at least one default speed ratio when the transmission is operating in a reverse speed ratio and the default condition occurs.

[0004] In one example, the first default speed ratio is a speed ratio corresponding to a forward speed ratio of the direct drive of the transmission, and the second default speed ratio is an idle speed ratio of the transmission.

[0005] In another example, the first and second solenoids each have an energized and a de-energized configuration, and when the transmission is in the first of the at least one forward speed ratio, the first solenoid is in the energized configuration and supplies hydraulic pressure to the first control valve, while the second solenoid is in the energized configuration and does not supply hydraulic pressure to the second control valve. In a variation thereof, the first solenoid is in the de-energized configuration and does not supply hydraulic pressure to the first control valve, while the second solenoid is in the de-energized configuration and supplies hydraulic pressure to the second control valve when the transmission is in the first default speed ratio.

[0006] In another example, the first control valve comprises a first spool valve and the second control valve comprises a second spool valve configured for a faster stroke than the first spool valve.

[0007] In yet another example, the standard condition is a power failure. In a variation of this, the power failure affects a transmission control module electrically connected to the first and second solenoids.

[0008] In another example, the second magnet is a variable force magnet.

[0009] In another example, the control system further includes a plurality of linear force solenoids hydraulically connected to the standard hydraulic control system. In a variation thereof, the standard hydraulic control system is configured to selectively direct hydraulic pressure fluid to at least one of the plurality of linear force solenoid valves in each of the first and second standard speed ratios.

[0010] In another exemplary embodiment of the present disclosure, a hydraulic control system for a transmission is disclosed. The hydraulic control system includes a standard hydraulic control system including a first valve assembly having a first control valve controlled by a first solenoid and a second valve assembly having a second control valve controlled by a second solenoid. The first and second valve assemblies are configured to shift the transmission from a first forward speed ratio to a standard speed ratio based on an electrical signal to at least one of the first and second valve assemblies.

[0011] In one example, the first magnet is configured to receive the electrical signal, and the second magnet is configured to receive the electrical signal. In a variation, the electrical signal is a loss of electrical power for each of the first and second magnets.

[0012] In another example, the control system further includes a pump configured to supply pressurized hydraulic fluid to each of the first and second valve assemblies of the standard hydraulic control system independently of the electrical system.

[0013] In another example, the default speed ratio is a neutral speed ratio or a direct drive speed ratio.

[0014] In another exemplary embodiment of the present disclosure, a transmission is disclosed having an input member and an output member operable in at least one forward speed ratio between the output member and the input member and at least one reverse speed ratio between the output member and the input member. The transmission includes a plurality of planetary gear sets operatively connected to the input member and a plurality of selective clutches operatively connected to the plurality of planetary gear sets.Each of the plurality of selective clutches has an engaged configuration and a disengaged configuration, and the plurality of selective clutches are selectively engageable to establish the at least one forward speed ratio and the at least one reverse speed ratio between the output member and the input member. The transmission further includes a hydraulic control system hydraulically connected to the plurality of selective clutches and including a standard hydraulic control system.The default hydraulic control system is configured to selectively engage at least a first portion of the plurality of selective clutches to establish a first default speed ratio when the transmission is operating in the at least one forward speed ratio and experiencing a default condition, and is configured to selectively engage at least a second portion of the plurality of selective clutches to establish a second default speed ratio when the transmission is operating in the at least one reverse speed ratio and experiencing the default condition.

[0015] In one example thereof, the transmission further includes a pump configured to supply pressurized hydraulic fluid to the standard hydraulic control system. In a variation thereof, the pump is configured to supply hydraulic pressure to at least one of the plurality of selective clutches independently of the standard hydraulic control system, wherein the at least one of the plurality of selective clutches is in the engaged configuration. In another variation, the pump is configured to continue providing pressurized hydraulic fluid even when the transmission assumes the standard state.

[0016] In another example, the plurality of selective clutches includes a first selective clutch, a second selective clutch, a third selective clutch, a fourth selective clutch, a fifth selective clutch, and a sixth selective clutch. In a variation thereof, in the first default speed ratio, the second selective clutch and the third selective clutch are in the engaged configuration, and the first selective clutch, the fourth selective clutch, the fifth selective clutch, and the sixth selective clutch are in the disengaged configuration.In a further variation thereof, in the second standard speed ratio, the third selective clutch is in the engaged configuration and the first selective clutch, the second selective clutch, the fourth selective clutch, the fifth selective clutch, and the sixth selective clutch are in the disengaged configuration.

[0017] In another example, the standard hydraulic control system includes a first valve assembly having a first control valve hydraulically coupled to a first solenoid, and a second valve assembly having a second control valve hydraulically coupled to a second solenoid. In a variation thereof, both the first and second solenoids have an energized configuration and a de-energized configuration, and when the transmission is in the at least one forward speed ratio, the first solenoid is in the energized configuration and supplies hydraulic pressure to the first control valve, and the second solenoid is in the energized configuration and does not supply hydraulic pressure to the second control valve.In another variation, the first solenoid is in the de-energized configuration and does not supply hydraulic pressure to the first control valve, while the second solenoid is in the de-energized configuration and supplies hydraulic pressure to the second control valve when the transmission is in the first standard speed ratio.

[0018] In some instances, this disclosure and the claims use numerical terminology, such as first, second, third, and fourth, to refer to various operative transmission components and other components and features. This is not intended to denote an order of components. Rather, the numerical terminology is provided to assist the reader in identifying the component of interest and should not be narrowly interpreted to establish a particular order of components. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other features and advantages of this disclosure, as well as the manner in which they may be achieved, will become more apparent and better understood by reference to the following description of exemplary embodiments taken in conjunction with the accompanying drawings, in which: Fig. 1 is a schematic representation of a multi-speed transmission with four planetary gear sets, six selective clutches and eight connecting elements, Fig. 2A and Fig. 2B are schematic representations of an exemplary hydraulic control system for a multi-speed transmission with six selective clutches, Fig. 3 a schematic view of a standard hydraulic control system of the hydraulic control system of Fig. 2A and Fig. 2B is, Fig. 4 is a truth table describing the selective engagement of the six selective clutches from the Fig. 2A and Fig. 2B to provide nine forward gears or forward speed ratios, one reverse gear or reverse speed ratio, three neutral gears or speed ratios, and two standard gears or standard speed ratios, Fig. 5 a hydraulic control scheme of the hydraulic control system from the Fig. 2A and Fig. 2B, when the multi-speed planetary gear set operates in a first forward speed ratio, Fig. 6 a hydraulic control scheme of the hydraulic control system from the Fig. 2A and Fig. 2B, when the multi-speed planetary gear set operates in a first standard speed ratio, Fig. 7A is a partial schematic view of a standard hydraulic control system of the hydraulic control system of the Fig. 2A and Fig. 2B, when the multi-speed planetary gear set operates in the first forward speed ratio, Fig. 7B is a partial schematic view of the standard hydraulic control system of the hydraulic control system of the Fig. 2A and Fig. 2B, when the multi-speed planetary gear set operates in the first standard speed ratio, Fig. 8 a hydraulic control scheme of the hydraulic control system from the Fig. 2A and Fig. 2B, when the multi-speed planetary gear set operates in reverse speed ratio, Fig. 9 is a hydraulic control scheme of the hydraulic control system from the Fig. 2A and Fig. 2B, when the multi-speed planetary gear set operates in a second standard speed ratio, Fig. 10A is a partial schematic view of the standard hydraulic control system of the hydraulic control system of the Fig. 2A and Fig. 2B, when the multi-speed planetary gear set operates in the reverse speed ratio, and Fig. 10B is a partial schematic view of the standard hydraulic control system of the hydraulic control system of the Fig. 2A and Fig. 2B, when the multi-speed planetary gear set operates in the second standard speed ratio.

[0020] Like reference numerals indicate corresponding parts throughout the several views. The examples presented herein illustrate exemplary embodiments of the invention, and these examples are not to be construed as limiting the scope of the invention in any way. DETAILED DESCRIPTION OF THE DRAWINGS

[0021] To promote an understanding of the principles of the present disclosure, reference is now made to the embodiments illustrated in the drawings and described below. The embodiments illustrated below are not intended to be exhaustive or to limit the present disclosure to the precise form described in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings. This is not intended to limit the scope of the present disclosure. Corresponding reference characters indicate corresponding parts throughout the several views.

[0022] In the exemplary embodiment of the transmission, torque and rotational motion are transmitted from an input member to an output member via a multi-speed gear train. To facilitate the transmission of torque and rotational motion to the output member at various selected speed ratios, the multi-speed transmission includes a plurality of operative transmission components. Simply stated, an operative transmission component is a device or component that transmits torque and rotational motion within the transmission. One or more portions of the operative transmission component may be rotatable to form a rotatable transmission component. Examples of operative transmission components include selective clutches, interconnecting members, sun gears, planet carriers, and ring gears.

[0023] A clutch is an example of a selective coupling. A clutch connects two or more rotating components together such that, in an engaged configuration, the two or more rotating components rotate as a unit and, in the disengaged position, permit relative rotation between the two or more rotating components. Example clutches may be switchable frictional multi-plate clutches, switchable positive jaw or cone clutches, wet clutches, or any other known form of clutch. The terms "connecting," "connected," "clutch," and variations thereof include arrangements in which the two or more components are in direct physical contact, as well as arrangements in which the two or more components are not in direct contact (e.g.,the components are “connected” via at least one third component, but still work together or interact with each other.

[0024] A second example of a selective coupling is a brake. A brake connects one or more rotatable components to a stationary component to hold the one or more rotatable components fixed relative to the stationary component in the engaged configuration and to allow rotation of the one or more components relative to the stationary component in the disengaged configuration. Example brakes may be embodied as sliding frictional disc brakes, sliding frictional band brakes, sliding positive dog or cone brakes, or any other known form of brake.

[0025] Selective clutches can be actively controlled devices or passive devices. Examples of actively controlled devices include hydraulically actuated clutch or brake elements and electrically actuated clutch or brake elements. Further details on systems and methods for controlling selective clutches are disclosed in US Pat. No. 9,625,007 B2.

[0026] In addition to coupling via selective clutches, various components of the disclosed transmission designs may be rigidly connected to one another throughout operation of the disclosed transmissions. The components may be rigidly connected to one another either permanently or releasably. The components may be rigidly connected to one another by splined joints, fasteners, welding, machined or formed functional parts of a single piece, interference fit joints, or other suitable component connection methods.

[0027] Connecting elements comprise one or more rotating components, such as shafts, drums, and other components, that are rigidly connected to one another. Connecting elements may also be rigidly connected to one or more other operative transmission components.

[0028] Fig. 1 is a schematic representation of an exemplary multi-speed transmission 100. The multi-speed transmission 100 includes an input member 102 and an output member 104. Both the input member 102 and the output member 104 are rotatable relative to at least one stationary member 106. An exemplary input member 102 is a drive shaft or other suitable rotatable member. The input member 102 is rotated by a prime mover. Example prime movers include internal combustion engines, electric motors, hybrid propulsion systems, and other suitable drive systems. In one embodiment, the prime mover drives the input member indirectly via a clutch and / or a torque converter. An exemplary output member 104 is an output shaft or other suitable rotatable member. The output member 104 provides rotational power to one or more working components.Example working components include one or more drive wheels of a motor vehicle, a power take-off shaft, and other suitable devices. The output member 104 is rotated depending on the connections between the operative gear components of the transmission 100. By changing the connections of the operative gear components, the rotational speed of the output member 104 can be varied relative to the rotational speed of the input member 102. An example stationary member 106 is a housing of the multi-speed transmission 100. The housing may include a plurality of interconnected components. In the embodiment shown in FIG. Fig. 1, the drive member 102 enters the stationary member 106 at a first location or end 116 and the output member 104 exits the stationary member 106 at a second location or end 118.

[0029] The multi-speed transmission 100 includes at least one planetary gear set. In the exemplary embodiment of Fig. 1, the multi-speed transmission 100 includes a plurality of planetary gear sets, e.g., a first planetary gear set 108, a second planetary gear set 110, a third planetary gear set 112, and a fourth planetary gear set 114. In another embodiment, additional planetary gear sets may be included. Although the first planetary gear set 108, the second planetary gear set 110, the third planetary gear set 112, and the fourth planetary gear set 114 are illustrated as simple planetary gear sets, compound planetary gear sets may also be provided in some embodiments. Furthermore, the arrangement of the plurality of planetary gear sets is exemplary.

[0030] The first planetary gear set 108 includes a sun gear 120, a planet carrier 122 carrying a plurality of planet gears 124, and a ring gear 126. The second planetary gear set 110 includes a sun gear 130, a planet carrier 132 carrying a plurality of planet gears 134, and a ring gear 136. The third planetary gear set 112 includes a sun gear 140, a planet carrier 142 carrying a plurality of planet gears 144, and a ring gear 146. The fourth planetary gear set 114 includes a sun gear 150, a planet carrier 152 carrying a plurality of planet gears 154, and a ring gear 156.

[0031] The multi-speed transmission 100 further includes a plurality of selective clutches, shown as a first selective clutch 162, a second selective clutch 164, a third selective clutch 166, a fourth selective clutch 168, a fifth selective clutch 170, and a sixth selective clutch 172. In the illustrated embodiment, the first selective clutch 162 and the second selective clutch 164 are shifting clutches, and the third selective clutch 166, the fourth selective clutch 168, the fifth selective clutch 170, and the sixth selective clutch 172 are brakes. The axial positions of the shifting clutches and brakes relative to the plurality of planetary gear sets may vary from the illustrated axial positions. In alternative embodiments, any number of shifting clutches and brakes may be used.

[0032] The multi-speed transmission 100 includes several components that are fixedly connected to one another in the illustration. The input member 102 is fixedly connected to the sun gear member 120 of the first planetary gear set 108. The output member 104 is fixedly connected to fp152 of the fourth planetary gear set 114. The ring gear member 126 of the first planetary gear set 108 is fixedly connected to fp130 of fp110. The planet carrier member 122 of the first planetary gear set 108 is fixedly connected to fp132 of fp110 and the ring gear member 146 of the third planetary gear set 112. In alternative embodiments, one or more of the fixedly connected components are selectively connected to one another via one or more selective clutches.

[0033] The multi-speed transmission 100 can be described as a transmission with six interconnecting elements. The input element 102 is a first interconnecting element that provides both input torque and rotational motion to the multi-speed transmission 100 and is fixedly connected to the sun gear member 120 of the first planetary gear set 108. The input element 102 is also fixedly connected to fp162 and fp164. The output element 104 is a second interconnecting element that provides output torque and rotational motion to the multi-speed transmission 100. A third interconnecting element 180 fixedly connects fp140 of fp112 and fp150 of fp114. The third interconnecting element 180 is also fixedly connected to fp162. A fourth interconnecting element 182 fixedly connects fp142 of fp112 and fp156 of fp114. The fourth connecting element 182 is also firmly connected to fp164 and fp172.A fifth interconnecting element 184 rigidly connects the planet carrier 132 of the second planetary gear set 110 to fp132 of fp110 and fp146 of fp112. The fifth interconnecting element 184 is also rigidly connected to fp170. A sixth interconnecting element 186 rigidly connects fp126 of fp108 to fp130 of fp110. The sixth interconnecting element 186 is also rigidly connected to fp166. Each interconnecting element may include multiple components rigidly connected to one another.

[0034] The multi-speed transmission 100 also includes a plurality of components, shown selectively interconnected by selective clutches. Through the engagement of various combinations of the first selective clutch 162, the second selective clutch 164, the third selective clutch 166, the fourth selective clutch 168, the fifth selective clutch 170, and the sixth selective clutch 172, additional components of the multi-speed transmission 100 may be fixedly interconnected. Thus, the plurality of planetary gear sets and the plurality of selective clutches of the multi-speed transmission 100 may be interconnected in various arrangements to provide torque and rotational motion from the input member 102 to the output member 104 in a plurality of forward gears or forward speed ratios and reverse gears or reverse speed ratios. Fig. 1 is a representative view of an exemplary transmission. Further details of the exemplary transmission are disclosed in US Pat. No. 7,364,527 B2.

[0035] In the Fig. 2A and Fig. 2B, an exemplary hydraulic control system 200 for a multi-speed planetary transmission is illustrated. The control system 200 is configured to control the selective engagement of a plurality of selective clutches, e.g., a first selective clutch 202, a second selective clutch 204, a third selective clutch 206, a fourth selective clutch 208, a fifth selective clutch 210, and a sixth selective clutch 212 (see Fig. 4). The control system 200 is hydraulically connected to each of the selective clutches via an electro-hydraulic valve or a transfer solenoid assembly, e.g., a linear force solenoid assembly. More specifically, the first selective clutch 202 is controlled by a first linear force solenoid assembly 214, the second selective clutch 204 is controlled by a second linear force solenoid assembly 216, the third selective clutch 206 is controlled by a third linear force solenoid assembly 218, the fourth selective clutch 208 is controlled by a fourth linear force solenoid assembly 220, the fifth selective clutch 210 is controlled by a fifth linear force solenoid assembly 222, and the sixth selective clutch 212 is controlled by a sixth linear force solenoid assembly 224.

[0036] The first linear magnet assembly 214, the second linear magnet assembly 216, the third linear magnet assembly 218, the fourth linear magnet assembly 220, the fifth linear magnet assembly 222, and the sixth linear magnet assembly 224 each comprise a magnet assembly and a control valve having a valve body. The valve body has a chamber and associated hydraulic fluid ports. The associated hydraulic fluid ports are further connected to hydraulic channels formed in the valve body. A rotationally symmetrical valve spool is received in the chamber of the valve body and is sized to reciprocate therein. The valve spool includes a plurality of lands arranged along a central shaft of the valve spool. The central shaft is radially smaller than each of the lands.The valve spool is movable within the valve housing due to the forces of hydraulic pressure within the control valve and due to the selective energization of the solenoid assembly. Thus, the valve spool lands can selectively regulate the flow of hydraulic fluid through the fluid ports to control the engagement of the respective selective clutch and thus the operation of the multi-speed transmission. Further details regarding the structure and operation of the first linear solenoid assembly 214, the second linear solenoid assembly 216, the third linear solenoid assembly 218, the fourth linear solenoid assembly 220, the fifth linear solenoid assembly 222, and the sixth linear solenoid assembly 224 can be found in U.S. Patent Application Publication No. 2019 / 0178370, filed on December 6, 2018.

[0037] The control system 200 includes a torque converter 226, a main pump 228, and an auxiliary pump 230. The main pump 228 and the auxiliary pump 230 are configured to provide a primary supply of pressurized hydraulic fluid for selectively engaging the selective clutches. In the exemplary embodiment shown, the main pump 228 is a rotary or vane pump connected to a sump 232, and the auxiliary pump 230 is a gerotor pump connected to the sump 232 and driven by an electric motor. The auxiliary pump 230 is driven by the electric motor to provide the primary supply of pressurized hydraulic fluid when the prime mover is no longer providing rotary motion to the input member 102, e.g., when the prime mover is off.More specifically, the auxiliary pump 230 supplies sufficient hydraulic pressure to at least one of the selective clutches to bring the vehicle to a stop on an inclined surface. Whether the hydraulic pressure is sufficient may depend, for example, on the gross vehicle weight rating (GVWR) or the gross vehicle mass (GVM). While the auxiliary pump 230 is shown connected to the sump 232, the auxiliary pump 230 could also be connected to a sump separate from the sump 232. In other embodiments, the pumps 228, 230 may consist of a different type of positive displacement pump. In further embodiments, the pumps 228, 230 may be identical positive displacement pumps.

[0038] The torque converter 226, the main pump 228, the auxiliary pump 230, the first linear magnet assembly 214, the second linear magnet assembly 216, the third linear magnet assembly 218, the fourth linear magnet assembly 220, the fifth linear magnet assembly 222, and the sixth linear magnet assembly 224 are hydraulically connected to one another via various components, such as a main regulator valve 234, a main accumulator valve 236, a main variable force solenoid valve 238, a torque converter blowoff valve 240, a torque converter feed limit valve 242, a lubricant feed limit valve 246, a torque converter flow valve 248, a thermal cooling bypass valve and cooler 250, a main control valve 252, a torque converter trim valve 254, a first exhaust gas return relief valve 256, and a second Exhaust gas return pressure relief valve 258.

[0039] The control system 200 also includes a standard hydraulic control system 260 hydraulically connected to the main pump 228, the first linear solenoid assembly 214, the second linear solenoid assembly 216, the third linear solenoid assembly 218, the fourth linear solenoid assembly 220, the fifth linear solenoid assembly 222, and the sixth linear solenoid assembly 224. The standard control system 260 includes a first valve assembly 262 and a second valve assembly 264. The first valve assembly 262 includes a solenoid 266 hydraulically connected to a control valve 268. Similarly, the second valve assembly 264 includes a solenoid 270 hydraulically connected to a control valve 272.

[0040] The standard hydraulic control system 260 is in Fig. 3 in more detail. The control valve 268 of the valve assembly 262 includes a valve body 274 having a chamber 276 and associated hydraulic fluid ports connected to hydraulic channels formed in the valve body 274. A rotationally symmetrical valve spool 278 is received in the chamber 276 of the valve body 274 and is dimensioned to move therein along an axis 280 between an actuated position (see Fig. 7A) and an unactuated position (see Fig. 10A). The valve spool 278 includes a plurality of lands arranged along a central shaft of the valve spool 278. The central shaft of the chamber 276 is radially smaller than each of the lands. The valve spool 278 is movable along the axis 280 within the valve housing 274 due to the forces of hydraulic pressure in the valve housing 274, the selective energization of the solenoid 266, and a biasing member 282 that biases the valve spool 278 to the unactuated position. In this manner, the lands of the valve spool 278 can selectively regulate the flow of hydraulic fluid through the fluid ports.

[0041] Solenoid 266 is hydraulically connected to control valve 268, as well as to main solenoid 238 and main control valve 252. In the exemplary embodiment shown, solenoid 266 is a hydraulic on / off solenoid that selectively applies hydraulic pressure to control valve 268 to move valve spool 278 along axis 280 from the unactuated position to the actuated position. More specifically, when solenoid 266 is energized, solenoid 266 applies hydraulic pressure to control valve 268 to move valve spool 278 to the actuated position. When solenoid 266 is de-energized, biasing member 282 urges valve spool 278 to the unactuated position. The selective energization of the solenoid 266 is controlled by a transmission control module (“TCM”) 284 that is electrically connected to the solenoid 266. More specifically, the TCM 284 provides an electrical signal, e.g.electrical energy to the magnet 266 to move the magnet 266 from a non-energized configuration or state to an energized state. In other embodiments, the magnet 266 may be a variable force magnet.

[0042] The control valve 272 of the valve assembly 264 includes a valve body 286 having a chamber 288 and associated hydraulic fluid ports connected to hydraulic channels formed in the valve body 286. A rotationally symmetrical valve spool 290 is received in the chamber 288 of the valve body 286 and is dimensioned to move therein along an axis 292 between an actuated position (see Fig. 7B) and an unactuated position (see Fig. 7A). The valve spool 290 includes a plurality of lands arranged along a central shaft of the valve spool 290. The central shaft of the valve spool 290 is radially smaller than each of the lands. The valve spool 290 is movable along the axis 292 within the valve housing 286 due to the forces of hydraulic pressure within the valve housing 286 and the selective energization of the variable force solenoid 270. The control valve 272 also includes a biasing element that tends to urge the valve spool 290 along the axis 292 to the unlocked position when no hydraulic pressure is applied to the opposite end of the valve spool 290. In this manner, the lands of the valve spool 290 can selectively regulate the flow of hydraulic fluid through the fluid ports.

[0043] Solenoid 270 is hydraulically connected to control valve 272, as well as to variable force main solenoid 238 and main control valve 252. In the exemplary embodiment shown, solenoid 270 is a variable force solenoid that selectively applies hydraulic pressure to chamber 276 to move valve spool 290 along axis 292 from the unactuated position to the actuated position. More specifically, when solenoid 270 is energized, it does not apply hydraulic pressure to control valve 272. As a result, valve spool 278 is movable along axis 292 depending on the hydraulic passage of valve body 286, which is pressurized with hydraulic fluid. When the solenoid 270 is not energized, the solenoid 270 applies hydraulic pressure to the control valve 272 to move the valve spool 278 to the actuated position (see Fig. 7B). The selective energization of solenoid 270 is controlled by TCM 284, which is electrically connected to solenoid 270. More specifically, TCM 284 provides an electrical signal, e.g., electrical power, to solenoid 270 to move solenoid 270 from a non-energized configuration or state to an energized state. In other embodiments, solenoid 270 may be a hydraulic on / off solenoid.

[0044] The control system 200 controls the selective engagement of the first selective clutch 202, the second selective clutch 204, the third selective clutch 206, the fourth selective clutch 208, the fifth selective clutch 210, and the sixth selective clutch 212 to establish at least nine forward speed ratios, at least one reverse speed ratio, at least one idle speed ratio, and at least one standard speed ratio. Fig. 4, an exemplary truth table 300 is shown providing the state of the first selective clutch 202, the second selective clutch 204, the third selective clutch 206, the fourth selective clutch 208, the fifth selective clutch 210, and the sixth selective clutch 212 for nine different forward gears or speed ratios, one reverse gear or speed ratio, three neutral gears or speed ratios, and two standard gears or speed ratios. Each row of the truth table 300 corresponds to a particular interconnection arrangement of the transmission that the control system 200 controls. The first column indicates the gear or speed range.The second through seventh columns show which of the first selective clutch 202, the second selective clutch 204, the third selective clutch 206, the fourth selective clutch 208, the fifth selective clutch 210, and the sixth selective clutch 212 are engaged (indicated by "1") and which of the first selective clutch 202, the second selective clutch 204, the third selective clutch 206, the fourth selective clutch 208, the fifth selective clutch 210, and the sixth selective clutch 212 are disengaged (indicated by "(empty)"). The eighth and ninth columns show which of the solenoids 266, 270 are energized (indicated by "On") and which of the solenoids 266, 270 are de-energized (indicated by "(empty)" or "Off").The ninth column also illustrates whether the solenoid 270 is applying hydraulic pressure to the valve spool 290 of the control valve 272 (indicated by “(Stroked)”) or whether the solenoid 270 is not applying hydraulic pressure to the valve spool 290 (indicated by “(Destroked)”). Fig. 4 is just one example of any number of truth tables possible for achieving at least nine forward speed ratios, at least one reverse speed ratio, at least one idle speed ratio, and at least one standard speed ratio.

[0045] In the example from Fig. 4, the illustrated reverse speed ratio (“Rev”) is achieved by the third selective clutch 206 and the fifth selective clutch 210 being in an engaged configuration, the first selective clutch 202, the second selective clutch 204, the fourth selective clutch 208, and the sixth selective clutch 212 being in a disengaged configuration, the solenoid 266 being de-energized, and the solenoid 270 being energized. The illustrated seventh forward speed ratio (“7”) is achieved when the second selective clutch 204 and the third selective clutch 206 are in an engaged configuration, the first selective clutch 202, the fourth selective clutch 208, the fifth selective clutch 210 and the sixth selective clutch 212 are in a disengaged configuration, the solenoid 266 is energized and the solenoid 270 is energized.A first default speed ratio (“forward default”) is achieved when the second selective clutch 204 and the third selective clutch 206 are in an engaged configuration, the first selective clutch 202, the fourth selective clutch 208, the fifth selective clutch 210, and the sixth selective clutch 212 are in a disengaged configuration, the solenoid 266 is de-energized, and the solenoid 270 is de-energized. A second default speed ratio (“reverse default”) is achieved by the third selective clutch 206 being in an engaged configuration, the first selective clutch 202, the second selective clutch 204, the fourth selective clutch 208, the fifth selective clutch 210, and the sixth selective clutch 212 being in a disengaged configuration, the solenoid 266 being de-energized, and the solenoid 270 being de-energized.

[0046] In the Fig. is a hydraulic control scheme of the control system 200 when the multi-speed transmission is operating in a first forward speed ratio, e.g., the seventh forward speed ratio (see row “7” of the truth table 300 in Fig. ). When the transmission is operating in the seventh speed ratio, the main pump 228 supplies pressurized hydraulic fluid to the first valve assembly 262, the second valve assembly 264, and the third selective clutch 206. The supply of pressurized hydraulic fluid to the third selective clutch 206 places the third selective clutch 206 in an engaged configuration. In the seventh forward speed ratio, the solenoid 266 of the first valve assembly 262 is energized, and the spool 278 of the control valve 268 is in the actuated position (see Fig. 7A). Therefore, the supply of pressurized hydraulic fluid to the first valve assembly 262 is directed through the control valve 268 to the second selective clutch 204 and the second valve assembly 264. In the seventh forward speed ratio, the solenoid 270 of the second valve assembly 264 is de-energized, and the valve spool 290 is free to move within the valve body 286 based on the hydraulic passage of the valve body 286 to which the pressurized hydraulic fluid is supplied (see Fig. 7A). Therefore, the supply of pressurized hydraulic fluid from the main pump 228 to the second valve assembly 264 is directed through the control valve 272 to the fourth selective clutch 208 and the fifth selective clutch 210, which are not engaged. In addition, the supply of pressurized hydraulic fluid from the first valve assembly 262 to the second valve assembly 264 is directed via the control valve 272 to the first selective clutch 202 and the sixth selective clutch 212, which are not arranged in an engaged configuration. The control system 200 maintains the transmission in the seventh forward speed ratio until the control system 200 receives a request or instruction to change the gear ratio or the transmission experiences a default condition. An example default condition is a loss of power to the TCM 284.For example, another default condition is a failure of the solenoid's electrical circuit. However, it is conceivable that other default conditions would cause the control system 200 to switch to one of the default forward or reverse speed ratios.

[0047] In the Fig. is a hydraulic control scheme of the control system 200 when the multi-speed transmission has entered a default state while operating at a first forward speed ratio and has been shifted to the default forward speed ratio (see row “Default Forward Speed Ratio” of the truth table 300 in Fig. ). When the transmission is operating in the standard forward speed ratio, the main pump 228 continues to supply pressurized hydraulic fluid to the first valve assembly 262, the second valve assembly 264, and the third selective clutch 206. The supply of pressurized hydraulic fluid to the third selective clutch 206 places the third selective clutch 206 in an engaged configuration. When the transmission experiences the standard condition, the solenoid 270 is deactivated based on an electrical signal to the solenoid 270 and supplies hydraulic pressure to the control valve 272 to translate the valve spool 290 along the axis 292 to the actuated position. Therefore, the supply of pressurized hydraulic fluid to the second valve assembly 264 is directed through the control valve 272 to the third selective clutch 206 and the first valve assembly 262.In the exemplary embodiment shown, the electrical signal sent to the magnet 270 is a loss of electrical power from the magnet 270.

[0048] When the transmission experiences the default condition, the solenoid 266 of the first valve assembly 262 is de-energized based on an electrical signal to the solenoid 266 and no longer supplies hydraulic pressure to the control valve 268. Therefore, the biasing member 282 attempts to bias the spool 278 toward the de-actuated position. However, the supply of pressurized hydraulic fluid from the second valve assembly 264 maintains the spool 278 of the control valve 268 in the actuated position because the spool 290 of the control valve 272 cycles faster than the spool 278 of the control valve 268. Therefore, the main supply of pressurized hydraulic fluid from the main pump 228 is directed through the first valve assembly 262 to the second selective clutch 204 and the second valve assembly 264.In the exemplary embodiment shown, the electrical signal sent to solenoid 266 is a loss of electrical power from solenoid 266. Hydraulic fluid directed from first valve assembly 262 to second valve assembly 264 does not flow through second valve assembly 264 due to the axial position of spool 290 of control valve 272. Hydraulic fluid from second valve assembly 264 to first valve assembly 262 is directed through first valve assembly 262 to second selective clutch 204. Supplying pressurized hydraulic fluid to second selective clutch 204 and third selective clutch 206 places second selective clutch 204 and third selective clutch 206 in an engaged configuration.

[0049] While the default forward speed ratio has been described in the context of the seventh forward speed ratio of the transmission, the control system 200 defaults to the default forward speed ratio when the transmission is operating in any of the at least nine forward speed ratios. One advantage of the seventh forward speed ratio of the control system 200 is, among other things, that the seventh forward speed ratio provides an overdrive forward speed ratio between the output member and the input member of the transmission. However, it is contemplated that the seventh forward speed ratio (or default forward speed ratio) could be, for example, a direct drive forward speed ratio.One advantage of the control system 200 and the standard hydraulic control system 260 is that an operator can control the moving vehicle and bring it to a stop when the standard condition occurs.

[0050] In the Fig. is a hydraulic control scheme of the control system 200 when the multi-speed transmission is operated in a first of the at least one reverse speed ratio (see row “REV” of the truth table 300 in Fig. ). When the transmission is operated in the reverse speed ratio, the main pump 228 supplies pressurized hydraulic fluid to the first valve assembly 262, the second valve assembly 264, and the third selective clutch 206. The supply of pressurized hydraulic fluid to the third selective clutch 206 places the third selective clutch 206 in an engaged configuration. In the reverse speed ratio, the solenoid 266 of the first valve assembly 262 is de-energized and does not supply hydraulic pressure to the control valve 268. Therefore, the biasing member 282 urges the valve spool 278 to the unactuated position (see Fig. 10a), and the supply of pressurized hydraulic fluid to the first valve assembly 262 does not pass through the first valve assembly 262 due to the axial position of the valve spool 278 of the control valve 268. In the reverse speed ratio, the solenoid 270 is energized and does not supply hydraulic pressure to the first valve assembly 262. Therefore, the valve spool 290 of the control valve 272 can move freely within the valve housing 286 based on the hydraulic passage of the valve housing 286, to which the pressurized hydraulic fluid is supplied (see Fig. 10A). The supply of pressurized hydraulic fluid to the second valve assembly 264 is directed by the control valve 272 to the fourth selective clutch 208, which is not in an engaged configuration, and to the fifth selective clutch 210, which is in an engaged configuration. The control system 200 maintains the transmission in the reverse speed ratio until the control system 200 receives a request or command to change the speed ratio or the transmission experiences a default condition, such as a loss of electrical power to the TCM 284.

[0051] In the Fig. is a hydraulic control scheme of the control system 200 when the multi-speed transmission has entered a default state during operation in the reverse speed ratio and has shifted to the standard reverse speed ratio (see line "Reverse Default" of the truth table 300 in Fig. ). While the transmission is operating in the standard reverse speed ratio, the main pump 228 continues to supply pressurized hydraulic fluid to the first valve assembly 262, the second valve assembly 264, and the third selective clutch 206. The supply of pressurized hydraulic fluid to the third selective clutch 206 places the third selective clutch 206 in an engaged configuration. When the transmission experiences the standard state, the solenoid 266 of the first valve assembly 262 is de-energized based on an electrical signal to the solenoid 266. Since the solenoid 266 of the first valve assembly 262 was already de-energized when the transmission was operating in the reverse speed ratio, the spool 278 of the control valve 268 remains in the unactuated position (see Fig. 10B). Therefore, the main supply of pressurized hydraulic fluid does not flow through the second valve assembly 262 because the valve spool 278 is in the axial position within the valve body 274 of the control valve 268. In the exemplary embodiment shown, the electrical signal sent to the solenoid 266 is maintained through a loss of electrical power from the solenoid 266.

[0052] When the transmission experiences the default condition, the solenoid 270 is de-energized based on an electrical signal to the solenoid 270 and supplies hydraulic pressure to the control valve 272 to move the valve spool 290 to the actuated position (see Fig.10B). Therefore, the main supply of pressurized hydraulic fluid to the second valve assembly 264 is routed through the control valve 272 to the third selective clutch 206 and to the first valve assembly 262. Because the valve spool 278 of the control valve 268 of the first valve assembly 262 is not actuated, the supply of pressurized hydraulic fluid from the second valve assembly 264 to the first valve assembly 262 is not routed through the first valve assembly 262. In the illustrated exemplary embodiment, the electrical signal sent to the solenoid 270 is a loss of electrical power from the solenoid 270.

[0053] One advantage of the default reverse speed ratio is that it allows a driver to control the moving vehicle and bring it to a stop when the default condition occurs. Furthermore, the default reverse speed ratio corresponds to a neutral transmission configuration. Because the vehicle is reversing at a low speed, the neutral reverse speed ratio configuration allows the driver to apply the brakes to bring the vehicle to a stop. Another advantage is that the neutral reverse speed ratio configuration signals to the driver that a default condition has occurred.

Claims

[1] A hydraulic control system for a transmission having an input member and an output member (102) operable in at least one forward speed ratio between the output member (104) and the input member (102) and in at least one reverse speed ratio between the output member (104) and the input member (102), comprising: a standard hydraulic control system (260) comprising: a first valve assembly (262) having a first control valve (268) controlled by a first solenoid (266), and a second valve assembly (264) having a second control valve (272) controlled by a second magnet (270), wherein the hydraulic default control system (260) is configured to shift the transmission into a first default speed ratio when the transmission is operating in a first of the at least one forward speed ratio and experiencing a default condition, and to shift the transmission into a second default speed ratio when the transmission is operating in a reverse speed ratio and experiencing the default condition, wherein the first control valve (268) comprises a first spool valve (278) and the second control valve comprises a second spool valve (272) configured to stroke faster than the first spool valve (278). [2] The control system of claim 1, wherein the first default speed ratio is a speed ratio corresponding to a direct drive forward speed ratio of the transmission, and the second default speed ratio is an idle speed ratio of the transmission. [3] The control system of claim 1, wherein each of the first and second solenoids (266, 270) has an energized configuration and a de-energized configuration, and when the transmission is in the first of the at least one forward speed ratios, the first solenoid (266) is in the energized configuration and supplies hydraulic pressure to the first control valve (268) and the second solenoid (270) is in the energized configuration and does not supply hydraulic pressure to the second control valve (272). [4] The control system of claim 3, wherein when the transmission is in the first default speed ratio, the first solenoid (266) is in the de-energized configuration and does not provide hydraulic pressure to the first control valve (268) and the second solenoid (270) is in the de-energized configuration and provides hydraulic pressure to the second control valve (272). [5] The control system of claim 1, wherein the default condition is a power failure. [6] The control system of claim 5, wherein the power failure affects a transmission control module (284) electrically connected to the first and second solenoids (266, 270). [7] The control system of claim 1, wherein the second magnet (270) is a variable force magnet. [8] The control system of claim 1, further comprising a plurality of linear force solenoid valves hydraulically connected to the standard hydraulic control system (260). [9] The control system of claim 8, wherein the standard hydraulic control system (260) is configured to selectively direct hydraulic pressure fluid to at least one of the plurality of linear force solenoid valves in each of the first and second standard speed ratios. [10] Hydraulic control system for a transmission, comprising: a standard hydraulic control system (260) comprising: a first valve assembly (262) having a first control valve (268) controlled by a first solenoid (266), and a second valve arrangement (264) with a second control valve (272) controlled by a second magnet (270), wherein the first and second valve assemblies (262, 264) are configured to shift the transmission from a first forward speed ratio to a standard speed ratio based on an electrical signal to at least one of the first and second valve assemblies (262, 264), wherein the first control valve (268) comprises a first spool valve (278) and the second control valve (272) comprises a second spool valve (290) configured to stroke faster than the first spool valve (278). [11] The control system of claim 10, wherein the first magnet (266) is configured to receive the electrical signal and the second magnet (270) is configured to receive the electrical signal. [12] The control system of claim 11, wherein the electrical signal is a loss of electrical power for each of the first and second magnets (266, 270). [13] The control system of claim 10, further comprising a pump (228) configured to supply pressurized hydraulic fluid to each of the first and second valve assemblies (262, 264) of the standard hydraulic control system (260) independently of the electrical system. [14] The control system of claim 10, wherein the default speed ratio is either an idle speed ratio or a direct drive speed ratio. [15] A transmission having an input member (102) and an output member (104) operable in at least one forward speed ratio between the output member (104) and the input member (102) and in at least one reverse speed ratio between the output member (104) and the input member (102), comprising: a plurality of planetary gear sets (108, 110, 112, 114) operatively coupled to the input member (102); a plurality of selective clutches (162, 164, 166, 168, 170, 172) operatively coupled to the plurality of planetary gear sets (108, 110, 112, 114), each of the plurality of selective clutches (162, 164, 166, 168, 170, 172) having an engaged configuration and a disengaged configuration, the plurality of selective clutches (162, 164, 166, 168, 170, 172) being selectively engageable to establish the at least one forward speed ratio and the at least one reverse speed ratio between the output member (104) and the input member (102), a hydraulic control system (260) hydraulically coupled to the plurality of selective clutches (162, 164, 166, 168, 170, 172) and including a standard hydraulic control system (260), wherein the hydraulic default control system (260) is configured to selectively engage at least a first portion of the plurality of selective clutches (162, 164, 166, 168, 170, 172) to establish a first default speed ratio when the transmission is operating in the at least one forward speed ratio and experiencing a default condition, and is configured to selectively engage at least a second portion of the plurality of selective clutches (162, 164, 166, 168, 170, 172) to establish a second default speed ratio when the transmission is operating in the at least one reverse speed ratio and experiencing the default condition, wherein the standard hydraulic control system (260) comprises: a first valve assembly (262) having a first control valve (268) hydraulically coupled to a first magnet (266), and a second valve arrangement (264) having a second control valve (272) hydraulically coupled to a second magnet (270), wherein the first control valve (268) comprises a first spool valve (278) and the second control valve (272) comprises a second spool valve (290) configured to stroke faster than the first spool valve (278). [16] The transmission of claim 15, further comprising a pump (228) configured to supply hydraulic fluid under pressure to the standard hydraulic control system (260). [17] The transmission of claim 16, wherein the pump (228) is configured to supply hydraulic fluid under pressure to at least one of the plurality of selective clutches (162, 164, 166, 168, 170, 172) independently of the standard hydraulic control system (260), the at least one of the plurality of selective clutches (162, 164, 166, 168, 170, 172) being arranged in the engaged configuration. [18] The transmission of claim 16, wherein the pump (228) is configured to continue supplying hydraulic fluid under pressure even when the transmission enters the standard state. [19] The transmission of claim 15, wherein the plurality of selective clutches (162, 164, 166, 168, 170, 172) comprises a first selective clutch (162), a second selective clutch (164), a third selective clutch (166), a fourth selective clutch (168), a fifth selective clutch (170), and a sixth selective clutch (172). [20] The transmission of claim 19, wherein in the first default speed ratio, the second selective clutch (164) and the third selective clutch (166) are in the engaged configuration and the first selective clutch (162), the fourth selective clutch (168), the fifth selective clutch (170), and the sixth selective clutch (172) are in the disengaged configuration. [21] The transmission of claim 20, wherein in the second default speed ratio, the third selective clutch (166) is in the engaged configuration and the first selective clutch (162), the second selective clutch (164), the fourth selective clutch (168), the fifth selective clutch (170), and the sixth selective clutch (172) are in the disengaged configuration. [22] The transmission of claim 15, wherein both the first and second magnets (266, 270) have an energized configuration and a de-energized configuration, and when the transmission is in the at least one forward speed ratio, the first magnet (266) is in the energized configuration and provides hydraulic pressure to the first control valve (268) and the second magnet (270) is in the energized configuration and does not provide hydraulic pressure to the second control valve (272). [23] The transmission of claim 22, wherein when the transmission is in the first default speed ratio, the first solenoid (266) is in the de-energized configuration and does not provide hydraulic pressure to the first control valve (268) and the second solenoid (270) is in the de-energized configuration and provides hydraulic pressure to the second control valve (272).

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