Patent Description:
<CIT> discloses an example of a power shift transmission.

One embodiment relates to a power shift transmission that includes a plurality of clutch valves, each clutch valve actuatable between an open position providing flow to a corresponding clutch pack and a closed position inhibiting flow to the corresponding clutch pack; and a hydraulic damping rail including a primary rail wall defining a primary rail volume, a rail inlet structured to provide communication of hydraulic fluid between a hydraulic pump and the primary rail volume, and a plurality of rail outlets, each rail outlet corresponding to one of the plurality of clutch valves and structured to provide communication between the primary rail volume and the corresponding one of the plurality of clutch valves. The hydraulic damping rail further includes a secondary rail wall defining a secondary rail volume and a first structure positioned within the secondary rail volume. The first damping structure includes a first piston movable between an extended position and a retracted position. The extended position and the retracted position define a travel length that defines a damping volume.

A non-claimed illustrative example relates to a method that includes providing pressurized hydraulic fluid from a pump to a damping volume of a hydraulic damping rail via a single rail inlet, providing pressurized hydraulic fluid from the damping volume to a plurality of clutch valves via a plurality of rail outlets, and damping noise and pressure fluctuations within the damping volume.

This summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the devices or processes described herein will become apparent in the detailed description set forth herein, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements.

According to an exemplary embodiment, a hydraulic damping rail of the present invention provides a damped hydraulic distribution structure that provides pressurized hydraulic fluid to clutch valves of a power shift transmission for a vehicle. The power shift transmission includes shafts, gears, and clutches and transfers power from the source of energy (e.g., an internal combustion engine) to a downstream tractive element (e.g., axles and wheels). If the load varies downstream, it may be advantageous to shift the gear up or down to keep the engine at its optimal operating conditions. Also, gear shifting is important for maximizing the performance of the vehicle (e.g., reducing fuel consumption). For example, while the vehicle (e.g., a tractor) is ploughing in a field and moving at eight kilometers per hour (<NUM> kph) with the transmission in seventh gear (i.e., gear <NUM>), if a hard section of soil is encountered and results in an increased load, the driver or the control system may downshift to sixth gear (i.e., gear <NUM>) and increase engine speed to keep the vehicle moving at eight kilometers per hour (<NUM> kph). If the load decreases in the field, the driver or the control system may upshift to eight gear (i.e., gear <NUM>) to maintain a desired vehicle speed. Gear shifting happens frequently during any vehicle operation and fast and smooth gear shifting is always desirable. The hydraulic damping rail discussed herein provides an improved gear shift speed and smoothness.

According to the exemplary embodiment shown in <FIG>, a machine or vehicle, shown as vehicle <NUM>, includes a chassis, shown as frame <NUM>; a body assembly, shown as body <NUM>, coupled to the frame <NUM> and having an occupant portion or section, shown as cab <NUM>; operator input and output devices, shown as operator interface <NUM>, that are disposed within the cab <NUM>; a drivetrain, shown as driveline <NUM>, coupled to the frame <NUM> and at least partially disposed under the body <NUM>; a vehicle braking system, shown as braking system <NUM>, coupled to one or more components of the driveline <NUM> to facilitate selectively braking the one or more components of the driveline <NUM>; a hydraulic system <NUM> for providing hydraulic power to vehicle systems or coupled implements; and a vehicle control system, shown as control system <NUM>, coupled to the operator interface <NUM>, the driveline <NUM>, and the braking system <NUM>. In other embodiments, the vehicle <NUM> includes more or fewer components.

According to an exemplary embodiment, the vehicle <NUM> is an off-road machine or vehicle. In some embodiments, the off-road machine or vehicle is an agricultural machine or vehicle such as a tractor, a telehandler, a front loader, a combine harvester, a grape harvester, a forage harvester, a sprayer vehicle, a windrower, and/or another type of agricultural machine or vehicle. In some embodiments, the off-road machine or vehicle is a construction machine or vehicle such as a skid steer loader, an excavator, a backhoe loader, a wheel loader, a bulldozer, a telehandler, a motor grader, and/or another type of construction machine or vehicle. In some embodiments, the vehicle <NUM> includes one or more coupled implements (e.g., hitched and/or trailed implements) such as a front mounted mower, a rear mounted mower, a trailed mower, a tedder, a rake, a baler, a plough, a cultivator, a rotavator, a tiller, a harvester, and/or another type of attached implement or trailed implement.

According to an exemplary embodiment, the cab <NUM> is configured to provide seating for an operator (e.g., a driver, etc.) of the vehicle <NUM>. In some embodiments, the cab <NUM> is configured to provide seating for one or more passengers of the vehicle <NUM>. According to an exemplary embodiment, the operator interface <NUM> is configured to provide an operator with the ability to control one or more functions of and/or provide commands to the vehicle <NUM> and the components thereof (e.g., turn on, turn off, drive, turn, brake, engage various operating modes, raise/lower an implement, etc.). The operator interface <NUM> may include one or more displays and one or more input devices. The one or more displays may be or include a touchscreen, a LCD display, a LED display, a speedometer, gauges, warning lights, etc. The one or more input device may be or include a steering wheel, a joystick, buttons, switches, knobs, levers, an accelerator pedal, a brake pedal, etc..

According to an exemplary embodiment, the driveline <NUM> is configured to propel the vehicle <NUM>. As shown in <FIG>, the driveline <NUM> includes a primary driver, shown as prime mover <NUM>, and an energy storage device, shown as energy storage <NUM>. In some embodiments, the driveline <NUM> is a conventional driveline whereby the prime mover <NUM> is an internal combustion engine and the energy storage <NUM> is a fuel tank. The internal combustion engine may be a spark-ignition internal combustion engine or a compression-ignition internal combustion engine that may use any suitable fuel type (e.g., diesel, ethanol, gasoline, natural gas, propane, etc.). In some embodiments, the driveline <NUM> is an electric driveline whereby the prime mover <NUM> is an electric motor and the energy storage <NUM> is a battery system. In some embodiments, the driveline <NUM> is a fuel cell electric driveline whereby the prime mover <NUM> is an electric motor and the energy storage <NUM> is a fuel cell (e.g., storing hydrogen, producing electricity from the hydrogen, etc.). In some embodiments, the driveline <NUM> is a hybrid driveline whereby (i) the prime mover <NUM> includes an internal combustion engine and an electric motor/generator and (ii) the energy storage <NUM> includes a fuel tank and/or a battery system.

As shown in <FIG>, the driveline <NUM> includes a transmission device (e.g., a gearbox, a continuous variable transmission ("CVT"), etc.), shown as transmission <NUM>, coupled to the prime mover <NUM>; a power divider, shown as transfer case <NUM>, coupled to the transmission <NUM>; a first tractive assembly, shown as front tractive assembly <NUM>, coupled to a first output of the transfer case <NUM>, shown as front output <NUM>; and a second tractive assembly, shown as rear tractive assembly <NUM>, coupled to a second output of the transfer case <NUM>, shown as rear output <NUM>. According to an exemplary embodiment, the transmission <NUM> has a variety of configurations (e.g., gear ratios, etc.) and provides different output speeds relative to a mechanical input received thereby from the prime mover <NUM>. In some embodiments (e.g., in electric driveline configurations, in hybrid driveline configurations, etc.), the driveline <NUM> does not include the transmission <NUM>. In such embodiments, the prime mover <NUM> may be directly coupled to the transfer case <NUM>. According to an exemplary embodiment, the transfer case <NUM> is configured to facilitate driving both the front tractive assembly <NUM> and the rear tractive assembly <NUM> with the prime mover <NUM> to facilitate front and rear drives (e.g., an all-wheel-drive vehicle, a four-wheel-drive vehicle, etc.). In some embodiments, the transfer case <NUM> facilitates selectively engaging rear drive only, front drive only, and both front and rear drive simultaneously. In some embodiments, the transmission <NUM> and/or the transfer case <NUM> facilitate selectively disengaging the front tractive assembly <NUM> and the rear tractive assembly <NUM> from the prime mover <NUM> (e.g., to permit free movement of the front tractive assembly <NUM> and the rear tractive assembly <NUM> in a neutral mode of operation). In some embodiments, the driveline <NUM> does not include the transfer case <NUM>. In such embodiments, the prime mover <NUM> or the transmission <NUM> may directly drive the front tractive assembly <NUM> (i.e., a front-wheel-drive vehicle) or the rear tractive assembly <NUM> (i.e., a rear-wheel-drive vehicle).

As shown in <FIG> and <FIG>, the front tractive assembly <NUM> includes a first drive shaft, shown as front drive shaft <NUM>, coupled to the front output <NUM> of the transfer case <NUM>; a first differential, shown as front differential <NUM>, coupled to the front drive shaft <NUM>; a first axle, shown front axle <NUM>, coupled to the front differential <NUM>; and a first pair of tractive elements, shown as front tractive elements <NUM>, coupled to the front axle <NUM>. In some embodiments, the front tractive assembly <NUM> includes a plurality of front axles <NUM>. In some embodiments, the front tractive assembly <NUM> does not include the front drive shaft <NUM> or the front differential <NUM> (e.g., a rear-wheel-drive vehicle). In some embodiments, the front drive shaft <NUM> is directly coupled to the transmission <NUM> (e.g., in a front-wheel-drive vehicle, in embodiments where the driveline <NUM> does not include the transfer case <NUM>, etc.) or the prime mover <NUM> (e.g., in a front-wheel-drive vehicle, in embodiments where the driveline <NUM> does not include the transfer case <NUM> or the transmission <NUM>, etc.). The front axle <NUM> may include one or more components.

As shown in <FIG> and <FIG>, the rear tractive assembly <NUM> includes a second drive shaft, shown as rear drive shaft <NUM>, coupled to the rear output <NUM> of the transfer case <NUM>; a second differential, shown as rear differential <NUM>, coupled to the rear drive shaft <NUM>; a second axle, shown rear axle <NUM>, coupled to the rear differential <NUM>; and a second pair of tractive elements, shown as rear tractive elements <NUM>, coupled to the rear axle <NUM>. In some embodiments, the rear tractive assembly <NUM> includes a plurality of rear axles <NUM>. In some embodiments, the rear tractive assembly <NUM> does not include the rear drive shaft <NUM> or the rear differential <NUM> (e.g., a front-wheel-drive vehicle). In some embodiments, the rear drive shaft <NUM> is directly coupled to the transmission <NUM> (e.g., in a rear-wheel-drive vehicle, in embodiments where the driveline <NUM> does not include the transfer case <NUM>, etc.) or the prime mover <NUM> (e.g., in a rear-wheel-drive vehicle, in embodiments where the driveline <NUM> does not include the transfer case <NUM> or the transmission <NUM>, etc.). The rear axle <NUM> may include one or more components. According to the exemplary embodiment shown in <FIG>, the front tractive elements <NUM> and the rear tractive elements <NUM> are structured as wheels. In other embodiments, the front tractive elements <NUM> and the rear tractive elements <NUM> are otherwise structured (e.g., tracks, etc.). In some embodiments, the front tractive elements <NUM> and the rear tractive elements <NUM> are both steerable. In other embodiments, only one of the front tractive elements <NUM> or the rear tractive elements <NUM> is steerable. In still other embodiments, both the front tractive elements <NUM> and the rear tractive elements <NUM> are fixed and not steerable.

In some embodiments, the driveline <NUM> includes a plurality of prime movers <NUM>. By way of example, the driveline <NUM> may include a first prime mover <NUM> that drives the front tractive assembly <NUM> and a second prime mover <NUM> that drives the rear tractive assembly <NUM>. By way of another example, the driveline <NUM> may include a first prime mover <NUM> that drives a first one of the front tractive elements <NUM>, a second prime mover <NUM> that drives a second one of the front tractive elements <NUM>, a third prime mover <NUM> that drives a first one of the rear tractive elements <NUM>, and/or a fourth prime mover <NUM> that drives a second one of the rear tractive elements <NUM>. By way of still another example, the driveline <NUM> may include a first prime mover that drives the front tractive assembly <NUM>, a second prime mover <NUM> that drives a first one of the rear tractive elements <NUM>, and a third prime mover <NUM> that drives a second one of the rear tractive elements <NUM>. By way of yet another example, the driveline <NUM> may include a first prime mover that drives the rear tractive assembly <NUM>, a second prime mover <NUM> that drives a first one of the front tractive elements <NUM>, and a third prime mover <NUM> that drives a second one of the front tractive elements <NUM>. In such embodiments, the driveline <NUM> may not include the transmission <NUM> or the transfer case <NUM>.

As shown in <FIG>, the driveline <NUM> includes a power-take-off ("PTO"), shown as PTO <NUM>. While the PTO <NUM> is shown as being an output of the transmission <NUM>, in other embodiments the PTO <NUM> may be an output of the prime mover <NUM>, the transmission <NUM>, and/or the transfer case <NUM>. According to an exemplary embodiment, the PTO <NUM> is configured to provide rotary power for driving an attached implement and/or a trailed implement of the vehicle <NUM>. In some embodiments, the driveline <NUM> includes a PTO clutch positioned to selectively decouple the driveline <NUM> from the attached implement and/or the trailed implement of the vehicle <NUM> (e.g., so that the attached implement and/or the trailed implement is only operated when desired, etc.).

According to an exemplary embodiment, the braking system <NUM> includes one or more brakes (e.g., disc brakes, drum brakes, in-board brakes, axle brakes, etc.) positioned to facilitate selectively braking (i) one or more components of the driveline <NUM> and/or (ii) one or more components of a trailed implement. In some embodiments, the one or more brakes include (i) one or more front brakes positioned to facilitate braking one or more components of the front tractive assembly <NUM> and (ii) one or more rear brakes positioned to facilitate braking one or more components of the rear tractive assembly <NUM>. In some embodiments, the one or more brakes include only the one or more front brakes. In some embodiments, the one or more brakes include only the one or more rear brakes. In some embodiments, the one or more front brakes include two front brakes, one positioned to facilitate braking each of the front tractive elements <NUM>. In some embodiments, the one or more front brakes include at least one front brake positioned to facilitate braking the front axle <NUM>. In some embodiments, the one or more rear brakes include two rear brakes, one positioned to facilitate braking each of the rear tractive elements <NUM>. In some embodiments, the one or more rear brakes include at least one rear brake positioned to facilitate braking the rear axle <NUM>. Accordingly, the braking system <NUM> may include one or more brakes to facilitate braking the front axle <NUM>, the front tractive elements <NUM>, the rear axle <NUM>, and/or the rear tractive elements <NUM>. In some embodiments, the one or more brakes additionally include one or more trailer brakes of a trailed implement attached to the vehicle <NUM>. The trailer brakes are positioned to facilitate selectively braking one or more axles and/or one more tractive elements (e.g., wheels, etc.) of the trailed implement.

With continued reference to <FIG>, the hydraulic system <NUM> may be directly driven by the prime mover <NUM>, by a secondary prime mover (e.g., an electric machine, an onboard generator set, etc.) or by another portion of the driveline <NUM>.

The hydraulic system <NUM> provides hydraulic power to the transmission <NUM>. In some embodiments, the transmission <NUM> includes a hydraulic power shift transmission including clutch packs that are selectively engaged and disengaged to adjust a gear ratio of the transmission <NUM>. Each clutch pack may be controlled by a hydraulic valve (e.g., an electrically actuated solenoid valve) that selectively provides hydraulic flow or inhibits hydraulic flow to engage or disengage the clutch pack. In some examples, each clutch pack is arranged as a normally disengaged clutch pack and includes a spring or other biasing element that provides a bias toward a disengaged arrangement of the clutch pack, and hydraulic fluid pressure provided by the hydraulic valve can overcome the bias to move the clutch pack into an engaged arrangement. In some embodiments, each clutch pack can be arranged as a normally engaged clutch pack and the application of hydraulic fluid pressure via the hydraulic valve can move the clutch pack toward the disengaged arrangement.

In some embodiments, the transmission <NUM> includes a plurality of clutch packs. Each clutch pack is arranged in communication with the control system <NUM> to selectively engage and disengage the clutch packs of the transmission <NUM> to provide a desired gear ratio. In some embodiments, the control system <NUM> receives inputs from the operator interface <NUM> and implements a gear ratio selected by an operator via the operator interface <NUM>. For example, the operator interface may include a paddle shift interface that is engagable by the operator to select the desired gear ratio. The control system <NUM> can include an engine control unit (ECU), a transmission control unit (TCU), a brake controller, an after treatment system control unit, a PTO control unit, a hydraulic system control unit, or any other controller, control system, or processor of the vehicle <NUM>. The control system <NUM> described herein includes processing circuits and memory that is capable of providing the functionality of systems, apparatuses, and methods described herein. In some embodiments, the functions of the control system <NUM> described herein may be spread between multiple physical controllers distributed through the vehicle <NUM> or may include cloud computing functions residing in a cloud or server remote from the vehicle <NUM>. In some embodiments, the control system <NUM> described herein may be provided on a single control unit including processing circuits and memory.

Some non-claimed illustrative examples include methods, systems, and program products on any machine-readable media for accomplishing various operations. The examples may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Examples include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

Although the figures and description may illustrate a specific order of method steps, the order of such steps may differ from what is depicted and described, unless specified differently above. Also, two or more steps may be performed concurrently or with partial concurrence, unless specified differently above. Such variation may depend, for example, on the software and hardware systems chosen and on designer choice. Likewise, software implementations of the described methods could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps, and decision steps.

The term "client or "server" include all kinds of apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, a system on a chip, or multiple ones, or combinations, of the foregoing. The apparatus may include special purpose logic circuitry, e.g., a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). The apparatus may also include, in addition to hardware, code that creates an execution environment for the computer program in question (e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, a cross-platform runtime environment, a virtual machine, or a combination of one or more of them). The apparatus and execution environment may realize various different computing model infrastructures, such as web services, distributed computing and grid computing infrastructures.

The systems and methods may be completed by any computer program. A computer program (also known as a program, software, software application, script, or code) may be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and it may be deployed in any form, including as a stand-alone program or as a module, component, subroutine, object, or other unit suitable for use in a computing environment. A program may be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program may be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

The processes and logic flows described in this specification may be performed by one or more programmable processors executing one or more computer programs to perform actions by operating on input data and generating output. The processes and logic flows may also be performed by, and apparatus may also be implemented as, special purpose logic circuitry (e.g., an FPGA or an ASIC).

Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data (e.g., magnetic, magneto-optical disks, or optical disks). Moreover, a computer may be embedded in another device (e.g., a vehicle, a Global Positioning System (GPS) receiver, etc.). Devices suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices (e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD ROM and DVD-ROM disks).

To provide for interaction with a user, implementations of the subject matter described in this specification may be implemented on a computer having a display device (e.g., a CRT (cathode ray tube), LCD (liquid crystal display), OLED (organic light emitting diode), TFT (thin-film transistor), or other flexible configuration, or any other monitor for displaying information to the user. Other kinds of devices may be used to provide for interaction with a user as well; for example, feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback).

Implementations of the subject matter described in this specification may be implemented in a computing system that includes a back-end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front end component (e.g., a client computer) having a graphical user interface or a web browser through which a user may interact with an implementation of the subject matter described in this disclosure, or any combination of one or more such back end, middleware, or front end components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include a LAN and a WAN, an inter-network (e.g., the Internet), and peer-to-peer networks (e.g., ad hoc peer-to-peer networks).

As shown in <FIG>, the hydraulic system <NUM> includes a pump <NUM> that provides hydraulic power in the form of a flow of pressurized hydraulic fluid, and a drain or sump <NUM> to which hydraulic fluid returns and is drawn from by the pump <NUM>. As discussed above, in some embodiments, the pump <NUM> is driven by the driveline <NUM>. In some embodiments, the pump <NUM> is a piston pump that generates pressure by a system of springs, a plate, and a rotating shaft. In some embodiments, other pump types are included.

The transmission <NUM> includes a hydraulic damping rail <NUM> receiving hydraulic fluid from the pump <NUM>, hydraulic clutch valves 126a-h that selectively provide hydraulic fluid to clutch packs of the transmission <NUM>, and a manifold or valve block <NUM> that connects each clutch valve 126a-h to the hydraulic damping rail <NUM>. The transmission <NUM> includes gears and shafts, and operation of a clutch system of the transmission <NUM> is an important contributor to a performance of the transmission <NUM>. Operation of the clutch system includes the engagement and disengagement of different clutches or clutch packs to realize the effective transfer of power. Coordinated timing of clutch pack engagement and disengagement provides effective change of a transmission gear ratio. In the clutch system, many hydraulic clutch valves 126a-h are connected to a single hydraulic pump <NUM>. In some embodiments, the generated pressure fluctuates with rotation of the pump <NUM>. Additionally, the opening and closing of the hydraulic clutch valves 126a-h changes the hydraulic fluid flow rate and causes a pressure noise in the hydraulic system <NUM>. The pressure fluctuations and system noise can affect the performance of the hydraulic clutch valves 126a-h.

The hydraulic damping rail <NUM> includes a rail inlet <NUM> positioned in a first side of the hydraulic damping rail <NUM> that receives hydraulic fluid from the pump <NUM>, and rail outlets 134a-h positioned on a second side of the hydraulic damping rail <NUM> opposite of the first side and each rail outlet 134a-h corresponding to a corresponding clutch valve 126a-h. While eight clutch valves 126a-h are shown and described, the transmission <NUM> can include any number of clutch valves <NUM> and corresponding clutch packs. For example, less than eight or more than eight clutch packs and corresponding clutch valves <NUM> are contemplated. The number of rail outlets <NUM> is matched to the number of clutch packs and clutch valves <NUM>. In other words, the number of rail outlets <NUM> equals the number of clutch valves <NUM>. In some embodiments, the rail outlets 134a-h are all spaced equidistant from each other. In some embodiments, the rail outlets 134a-h define variable spacing. For example, spacing near the rail inlet <NUM> may be larger than spacing further from the rail inlet <NUM>. In some embodiments, more than one hydraulic damping rail <NUM> may be provided to provide hydraulic fluid to more than one set of clutch valves 126a-h. For example, as shown in <FIG>, a hydraulic damping rail <NUM>' and transmission <NUM>' are shown as optional components. The transmission <NUM>' may be a portion of the transmission <NUM>. For example, the hydraulic damping rail <NUM> may provide hydraulic fluid to a first set of clutch valves 126a-h and the hydraulic damping rail <NUM>' may provide hydraulic fluid to another set of clutch valves 126a-h'. In some embodiments, the second set of clutch valves may include a different number of clutch valves (e.g., more than <NUM> or less than eight). In some embodiments, more than two hydraulic damping rails may be included, as desired. In some embodiments, the hydraulic damping rail <NUM> may be integrated within a valve block as described below. The driveline <NUM> may include hydraulic damping rails <NUM> that are stand-alone units separate from the valve block, hydraulic damping rails that are integrated with a valve block as a single unit, or any combination of stand-alone and integrated hydraulic damping rails.

In some embodiments, the hydraulic damping rail <NUM> is physically separate from the valve block <NUM> and is mounted within the vehicle <NUM> in a location separate from the valve block <NUM>. The valve block <NUM> may be connected to the hydraulic damping rail <NUM> with hydraulic lines. In some embodiments, the hydraulic damping rail <NUM> defines a cylindrical shape. In some embodiments, the hydraulic damping rail <NUM> defines a rectangular shape or another shape, as desired. In some embodiments, the hydraulic damping rail <NUM> includes internal damping plates, bladder accumulators, piston accumulators, tortured hydraulic flow paths, internal baffles, or other structures that improve the even distribution and flow of hydraulic fluid to each of the rail outlets 134a-h.

As shown in <FIG>, an integrated damper block <NUM> includes the hydraulic damping rail <NUM> and the valve block <NUM> arranged in a single housing or as a single unit machined as a unitary item and structured to couple to the clutch valves 126a-e. In some embodiments, the hydraulic damping rail <NUM> may be formed as a separate component and fastened directly to the valve block <NUM> without intervening hydraulic lines to assemble the integrated damper block <NUM>.

The integrated damper block <NUM> defines a primary rail wall <NUM> that defines a primary rail volume. The rail inlet <NUM> is defined in the primary rail wall <NUM> and provides fluid communication between the pump <NUM> and the primary rail volume. The rail outlets 134a-e are also defined in the primary rail wall <NUM> and provide communication between the primary rail volume and the clutch valves 126a-e. In some embodiments, the primary rail wall <NUM> defines a cylindrical shape defining a primary diameter.

A secondary rail wall <NUM> is defined at a first end of the hydraulic damping rail <NUM> in fluid communication with the primary rail volume defined by the primary rail wall <NUM>. The secondary rail wall <NUM> defines a secondary rail volume in fluid communication with the primary rail volume. In some embodiments, the secondary rail wall <NUM> defines a cylindrical shape defining a secondary diameter that is greater than the primary diameter.

A first damping structure in the form of a first damping piston <NUM> is positioned within the secondary rail volume in sealing arrangement with the secondary rail wall <NUM> and movable between an extended position (shown in <FIG>) and a retracted position by hydraulic pressure against the bias of a first spring <NUM>. In some embodiments, the sealing arrangement allows a slow fluid flow past the first damping piston <NUM> so that hydraulic fluid is arranged on both sides of the first damping piston <NUM> but flow past the first damping piston <NUM> is significantly reduced. In some embodiments, the sealing arrangement inhibits the passage of hydraulic fluid into the secondary rail volume. For example, a sliding seal could be provided between the first damping piston <NUM> and the secondary rail wall <NUM>.

In some embodiments, the first spring <NUM> is a coil spring providing a predetermined spring bias to the first damping piston <NUM>. In some embodiments, the first spring <NUM> includes a pneumatic spring (e.g., a gas spring) that may be predetermined or adjustable via a pneumatic system or the control system <NUM>. In some embodiments, the first damping piston <NUM> and the first spring <NUM> are replaced with a diaphragm, a bladder accumulator, or another damping system, as desired.

A tertiary rail wall <NUM> is defined at a second end of the hydraulic damping rail <NUM> in fluid communication with the primary rail volume defined by the primary rail wall <NUM>. The tertiary rail wall <NUM> defines a tertiary rail volume in fluid communication with the primary rail volume. In some embodiments, the tertiary rail wall <NUM> defines a cylindrical shape defining a tertiary diameter that is greater than the primary diameter. In some embodiments, the tertiary diameter is equal to the secondary diameter.

A second damping structure in the form of a second damping piston <NUM> is positioned within the tertiary rail volume in sealing arrangement with the tertiary rail wall <NUM> and movable between an extended position and a retracted position (shown in <FIG>) by hydraulic pressure against the bias of a second spring <NUM>. In some embodiments, the sealing arrangement allows a slow fluid flow past the second damping piston <NUM> so that hydraulic fluid is arranged on both sides of the second damping piston <NUM> but flow past the second damping piston <NUM> is significantly reduced. In some embodiments, the sealing arrangement inhibits the passage of hydraulic fluid into the tertiary rail volume. For example, a sliding seal could be provided between the second damping piston <NUM> and the tertiary rail wall <NUM>.

In some embodiments, the second spring <NUM> is a coil spring providing a predetermined spring bias to the second damping piston <NUM>. In some embodiments, the second spring <NUM> includes a pneumatic spring (e.g., a gas spring) that may be predetermined or adjustable via a pneumatic system or the control system <NUM>. In some embodiments, the second damping piston <NUM> and the second spring <NUM> are replaced with a diaphragm, a bladder accumulator, or another damping system, as desired.

The first damping piston <NUM> and the second damping piston <NUM> each define a travel length <NUM>. The travel length <NUM> together with the secondary diameter and the tertiary diameter define a damping volume. A larger travel length <NUM> defines a larger damping volume. In some embodiments, the damping volume can refer to the entire usable volume of the hydraulic damping rail <NUM>.

The primary rail volume, the secondary rail volume, and/or the tertiary rail volume act as a pressure reservoir that damps the noise and fluctuations in hydraulic pressure distributed between the rail outlets 134a-e. The primary diameter is significantly larger than a typical hydraulic manifold or hydraulic line. Typical manifold and lines do not provide damping.

The integrated damper block <NUM> further defines a block inlet <NUM> arranged in communication between the pump <NUM> and the rail inlet <NUM>, and valve passages 174a-e that connect each clutch valve 126a-e to the corresponding rail outlet 134a-e.

Positioning the hydraulic damping rail <NUM> between the hydraulic pump <NUM> and the clutch valves 126a-e eliminates the fluctuations and pressure noise of the hydraulic system <NUM> caused by opening and closing of clutch valves 126a-e and the operation of the pump <NUM>. The hydraulic damping rail <NUM> operates as a pressure reservoir that absorbs the energy of waves of fluctuations and system noise. This can help faster operation of the clutch valves 126a-e and therefore provides improved gear shifting of the transmission <NUM>. The hydraulic damping rail <NUM> also decreases the hydraulic pump peak torque requirement and decrease the pump parasitic loss. Therefore, the hydraulic damping rail <NUM> increases the efficiency of the hydraulic system <NUM> and the vehicle <NUM>.

The hydraulic damping rail <NUM> reduces hydraulic system noise and pressure fluctuations, provides faster operation of the clutch valves 126a-e, enhances the performance of transmission <NUM> with smooth gear shifting, increases the efficiency of the hydraulic system <NUM> and the vehicle <NUM>, and reduces the pump peak torque requirement and parasitic loss. The integrated damper block <NUM> can also reduce the total number of components that need to be installed on the vehicle <NUM> and reduces the incidents of improper installation.

Claim 1:
A power shift transmission (<NUM>), comprising:
a plurality of clutch valves (126a-h), each clutch valve (126a-h) actuatable between an open position providing flow to a corresponding clutch pack and a closed position inhibiting flow to the corresponding clutch pack; and
a hydraulic damping rail (<NUM>) including
a primary rail wall (<NUM>) defining a primary rail volume;
a rail inlet (<NUM>) structured to provide communication of hydraulic fluid between a hydraulic pump (<NUM>) and the primary rail volume; and
a plurality of rail outlets (<NUM>), each rail outlet (<NUM>) corresponding to one of the plurality of clutch valves (126a-h) and structured to provide communication between the primary rail volume and the corresponding one of the plurality of clutch valves (126a-h);
wherein the hydraulic damping rail (<NUM>) further includes a secondary rail wall (<NUM>) defining a secondary rail volume;
wherein the hydraulic damping rail (<NUM>) further includes a first damping structure positioned within the secondary rail volume;
wherein the first damping structure includes a first piston (<NUM>) movable between an extended position and a retracted position;
wherein the extended position and the retracted position define a travel length (<NUM>) that defines a damping volume.