Abstract:
A transmission including a torque converter to transfer power from a driving engine to a driven device through a series of fluidly-activated clutches, particularly for use with industrial applications. By using a self-contained fluid system to engage the clutch at the idle speed of the driving engine, the transmission is provided with a positive neutral feature. The transmission is adaptable to all industrial engine housings. Additional optional features of the transmission include an auxiliary drive, a reverse and single or additional forward gears, and a fluid cooler. The transmission further includes a transmission output shaft supported by a bearing assembly that may be designed for side loading. The transmission provides the benefits of increased performance in torque demanding applications, self-lubricating features that eliminate grease fittings, load dampening, an auxiliary drive, and a throttle/clutch engagement system that eliminates clutch damage caused by improper high speed engagement.

Description:
FIELD OF THE INVENTION 
     This invention relates to an industrial transmission, and in particular to a power take off fluid transmission that includes a torque converter and mechanical clutches. 
     BACKGROUND 
     Use of power take offs (PTOs) to transmit engine power to a driven component, such as wood chipper or other industrial applications, are well known in the art. Manufacturers of existing systems include Rockford Powertrains of Rockford, Ill., Twin Disc of Racine, Wis., Funk Manufacturing of Coffeyville, Kans., and Stein Manufacturing. All of the PTOs produced by these manufacturers consist of a mechanical clutch that transfers the power of the engine through an output shaft by engaging a lever that is independent of engine controls. 
     A number of problems result from this approach. One problem is that in many cases, the operator increases engine speed (increased revolutions per minute or RPM) during engagement of the clutch so that the driven device may be driven by the engine without stalling the engine. Such high RPM engagement of existing mechanical clutches often damages, and in some cases destroys, the clutch and other components, including engine components and driven components. 
     Another problem with the PTOs of the prior art arises with regard to known methods for lubrication. Currently manufactured PTOs either provide too little or too much lubrication. Too little lubrication causes parts to wear and eventually seize, resulting in unit failure. On the other hand, too much lubrication causes slippage and eventual failure. Specifically, many of the industrial transmissions of the prior art include, for example, couplings and other parts that require periodic service lubrication. Lubrication for these parts, as well as protection from external elements, is typically provided through use of grease fittings attached to rubber hoses or other covers for the parts. In addition to causing failure of the lubricated parts, failure of these fittings or covers can also result in grease from the fittings interfering with the operation of other parts of the transmission, such as clutch plates. Such interference can also result from incorrect replenishing or spillage of grease when added to the fittings. Further, manufacturers may not provide clear or sufficient maintenance instructions for lubrication, or the lubrication needs may vary widely from standard recommended lubrication because of severe loads or uses of the driven device. 
     Another problem with the PTOs of the prior art is that these devices typically are limited to transmitting the same amount of power that the engine delivers. Thus, for example, if the load demand of the driven component exceeds the output power of the engine, a complete and sudden shutdown of the engine will occur, and in some cases, catastrophic damage can result. Another typical result of this event is excessive machine downtime. 
     Further, while it is known in the art to use torque converters in industrial applications, their use is often problematic. Torque converters, such as those produced by Transfluid Industrial Transmissions of Milano, Italy, can be difficult to use in many applications because their engagement and disengagement is controlled by fluid pressure, rather than a positive or direct engagement by an operator. The engagement of these torque converters at particular fluid pressures results from a combination of RPM of the driving engine and other factors that often cannot be controlled by the operator. For example, one such factor is the viscosity of the fluid medium, which can vary widely depending on temperature. Thus, it is often difficult for an operator to accurately control the engagement and disengagement of torque converters used in industrial applications. 
     Another problem with existing fluid-driven transmissions is high fluid pressure, which can result in stall conditions in applications lacking a positive neutral or positive engagement/disengagement feature. For example, some prior art fluid-driven transmissions include lead plugs within the drive housing. These plugs are released if excessive fluid pressure buildup occurs, such as in the event of stall. When the plugs are released, the fluid leaks out of the plug openings and creates a maintenance and potentially an environmental hazard. 
     Accordingly, there is a need for a variably engageable transmission for industrial applications. There is a further need for an industrial transmission that may not be engaged at speeds other than idle. There is a further need for an industrial transmission that is self-contained, self-lubricating, and self-cleaning to maximize performance and minimize part wear. Finally, there is a need for a transmission having the capability to multiply the torque capabilities of the driving engine. 
     Specifically, there is a need to provide a variable engageable transmission for industrial and other applications that incorporates use of a fluidly engageable clutch assembly and a torque converter. There is an additional need to provide a variably engageable transmission that overcomes the two major problems with use of a fluid coupling, which include lack of a positive neutral and the tendency of fluid couplings to overheat upon load stalls of more than 30 seconds. There is also a need for an industrial transmission that provides for direct application of power from the engine to the driven device, without complicating gears, and that is engageable simply through a combination throttle and clutch engagement feature. 
     SUMMARY OF THE INVENTION 
     This invention is a transmission that uses a torque converter and a fluid engagement system to transfer power from a driving engine to a driven device through a series of clutches that couple the torque converter input shaft to the transmission output shaft. By using a positively controlled fluid engagement system and clutches, the transmission may be mechanically switched between neutral and positive engagement with the driving engine. Further, by utilizing the torque converter and fluidly engaged clutches, the transmission advantageously provides load/shock absorption and dampening characteristics that reduce the stress on both the driving engine and on the driven device. Further, the fluid system used to engage the clutches is also utilized for lubrication of the other components of the transmission, which are all contained within a transmission housing. The transmission housing also includes a fluid reservoir for the storage and measurement of the fluid. Additional features of the transmission include an auxiliary drive coupled to the clutches that may be utilized to power auxiliary equipment. Further, the transmission is particularly for use with industrial applications, and particularly includes bearings supporting the transmission output shaft for stressful side loading applications. Thus, the transmission provides the benefits of increased performance in torque-demanding applications, self-lubricating features which eliminate grease fittings, load dampening, an auxiliary drive, and a throttle/clutch engagement system that eliminates clutch damage caused by improper high speed engagement. 
     The industrial transmission housing is coupled to the driving engine typically at the flywheel housing. The shaft of the torque converter of the transmission is connected to the engine&#39;s flywheel, and the flywheel serves to convey the engine&#39;s power to the transmission. The torque converter is coupled to a clutch assembly containing the clutches. The clutch assembly is connected to the transmission output shaft that is supported by the bearings. These transmission components are contained within the housing, which supports the output shaft bearings and has features for mounting the transmission to the engine. 
     The torque converter and clutch assembly have a positive neutral feature, where the positive neutral feature allows engagement and disengagement of the transmission from the driving engine via a combination throttle/shift mechanism coupled to both the driving engine and the transmission. Preferably, the throttle is incrementally advanceable such that the first increment engages the transmission without accelerating the engine RPMs, thereby allowing the transmission to be engaged only at idle. The throttle/shift mechanism eliminates wear from improper engagement, and in combination with the fluid engagement of the torque converter and clutch assembly comprises a “positive neutral” feature. Further, the throttle/shift mechanism may be mounted on the housing of the driving engine or the transmission. 
     The throttle/shift mechanism may be connected to the engine and transmission via a pair a cables. A first cable connects the combination to the engine and a second cable connects the combination to the transmission. As such, movement of the throttle/shift mechanism moves the second cable that mechanically activates a lever on the transmission. The lever on the transmission moves a directional valve that controls hydraulic activation of the clutch assembly for engaging the torque converter and the transmission output shaft. The directional valve places the transmission between neutral and operational settings, enabling engine operation without engaging the working components of the transmission or driven device. 
     The torque converter connects the mechanical elements of the transmission to the engine and transfers the power of the engine to the driven output device. Further, the torque converter serves to dampen any shock loads between the driven output device and the engine. In addition, the torque converter provides the capability to multiply the torque of the engine as transmitted to the driven output device or element. A further advantage of use of the torque converter is that severe shocks or catastrophic stops of the driven device or the engine are not directly transmitted through the torque converter, and any sudden changes in RPMs of either the engine or driven element are dampened through the torque converter. Further, the torque converter is contained within the transmission housing such that a loss of fluid from the torque converter is contained within the transmission housing. Thus, the torque converter advantageously provide torque multiplication combined with features that dampen the effect of excessive loads and prevent complete and sudden shutdowns, as well as limit catastrophic failures and downtime. 
     The torque converter drives a hydraulic pump that circulates the fluid through the fluid system. Functions of the hydraulic pump include: 1) filling the torque converter with fluid; 2) directing fluid to appropriate locations to lubricate all of the internal components of the transmission; 3) directing fluid to a directional valve that controls the clutches of the transmission; 4) circulating fluid to a cooler and back to the reservoir; and 5) filtering the fluid through an internal filter and one or more additional filters located throughout the transmission. An adjustable or fixed pressure regulator controls the pressure of the fluid within the system. Also, the cooler or radiator included as part of the fluid system continues to cool the fluid even during stall conditions. 
     The clutch assembly includes pressure, friction and drive plates that are engaged and disengaged by use of a directional valve within the fluid system. Engagement and disengagement of the plates in turn transfers and disengages power from the torque converter to the transmission output shaft. Preferably, the clutch assembly is specially designed to contain heavy pressure, friction and drive plates for industrial applications. 
     Additionally, the clutch assembly includes a spline coupling that engages a spline on the transmission output shaft. When the clutch assembly is engaged, the transmission output shaft becomes locked to the torque converter shaft. Further, the clutch plates may include notches or splines at their outside edges for engaging corresponding notches or splines on a clutch housing. Further, the clutch assembly includes an inner hub that extends through the middle of the clutch plates and through openings in hub engaging plates. The hub engaging plates have notches or splines in the openings that engage corresponding notches or splines on the inner hub. When the clutch is engaged, the clutch plates frictionally engage the engaging plates. Additionally, the clutch housing may include external lugs, splines or gear teeth that drive an auxiliary device, such as a shaft or hydraulic pump. Thus, through these splines, the transmission output shaft is engageable through the clutch assembly to the torque converter. 
     The transmission is a self-contained unit that uses a fluid as a medium for operation and the fluid also serves as a cleaner and lubricant for the components of the transmission. Thus, the fluid itself is a functional part of the unit and the transmission allows for exact measurement and use of the fluid in all appropriate locations. Also, the fluid by its nature has cleaning properties that further protect the internal parts of the transmission. 
    
    
     BRIEF DESCRIPTION THE FIGURES 
     FIG. 1 is a schematic view of one embodiment the industrial transmission of the present invention for use with an engine and a driven device; 
     FIG. 2 is an exploded view of the components of the industrial transmission of FIG. 1; 
     FIG. 3 is an end view of the industrial transmission of FIG. 2; 
     FIG. 4 is a block diagram of the hydraulic components and hydraulic flow of the industrial transmission of FIG. 2; and 
     FIG. 5 is a cross-sectional view of the industrial transmission of FIG.  3 . 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1, one embodiment of a transmission system  10  for use in industrial applications includes a driving engine  12  having a flywheel  14  and an engine output shaft  16  that is connected to a torque input end  18   a  of a shaft  18  forming part of a torque converter  20  of a transmission  22 . Extending from the transmission  22  is transmission output shaft  24 , which drives a driven device  26 , such as a wood chipper, leaf vacuum or other industrial device. Preferably, transmission  22  is for stationary applications. 
     The engine  12  speed and engagement of the transmission  22  is controlled by a variable controller  28 , such as a pivoting throttle/clutch lever/cable combination or other similar mechanism. The variable controller  28  is connected to the driving engine  12  through a first coupler  30 , for example a cable, that serves as a throttle control for the engine. Additionally, the variable controller  28  is connected to the industrial transmission  22  through a second coupler  32 , for example a cable or control linkage, that serves as an engagement mechanism for the transmission. 
     The variable controller  28  has an initial (engine idle) position in which the transmission  22  is not engaged (positive neutral), a first incremental position in which the transmission is engaged, and additional positions in which the engine speed may be accelerated while the transmission is engaged. The first position of engagement of the transmission  22  is via mechanical movement of a valve within the transmission, which in turn engages a clutch to fluidly couple the torque converter  20  through the transmission to the transmission output shaft  24 . 
     Referring to FIGS. 2 and 3, the transmission  22  includes a transmission housing  34  with a sump  36  providing a chamber for storage of fluid  37  (FIG. 5) and further including a fill opening/dipstick  38  for replenishing and measuring fluid levels. The transmission  22  also includes the transmission output shaft  24  having a shaft support member  40 , such as thrust or side load ball bearings. Further, the transmission  22  includes a clutch assembly  42  having a clutch hub  44  interacting with a clutch pack  46  adapted to be coupled with a clutch housing  48 . The clutch assembly  42  is coupled to a torque output end  18   b  of the shaft  18  of the torque converter  20 . The torque converter  20  further includes an impeller side  20   a  and a turbine side  20   b , and a shaft  18  that is connectable to, for example, the engine output shaft  16  (see FIG.  1 ). Optionally, a hydraulic pump  52  or other similar auxiliary power source may be coupled to torque output end  18   b  of shaft  18  to drive auxiliary devices. The hydraulic pump  52  or other auxiliary power source may include an auxiliary shaft supported by auxiliary shaft bearings that are lubricated by the fluid  37 . 
     In operation, driving engine  12  (FIG. 1) is coupled to transmission  22  through torque input end  18   a  of shaft  18 . The rotational energy of the driving engine  12  may be multiplied by the torque converter  20  and transferred through torque output end  18   b  of shaft  18  to transmission output shaft  24  through clutch assembly  42 . The transmission  22  has an overall gear ratio, where the gear ratio is a ratio of the rotation of input shaft  18  to the rotation of output shaft  24 . Preferably, the overall gear ratio is about 1:1, although the overall gear ratio may be varied to suit each particular application. Additionally, the optional hydraulic pump  52  also may utilize the rotational energy of the shaft  18  to drive auxiliary components. Thus, the power of the driving engine  12  is multiplied and transferred through the transmission  22  to the transmission output shaft  24  to smoothly power the driven device  26  (FIG.  1 ). 
     The industrial transmission  22  includes a positive neutral feature that only engages the transmission when the driving engine  12  is idling. In operation, referring to FIGS. 4 and 5, the coupling of the driving engine  12  to the industrial transmission  22  through the torque converter  20  causes a fluid flow through the industrial transmission  22  without engaging clutch assembly  42 . In effect, the fluid is flowing through a bypass circuit until redirected to engage the clutch. With the start of rotation of the driving engine  12 , the engine rotation is transferred through the torque converter  20  to the torque output end  18   b  of shaft  18  which turns the hydraulic pump  52 . The hydraulic pump  52  initiates a fluid flow  54   a  from the sump  36 , where it is drawn through a strainer  56  such as a filter. The fluid is drawn through the hydraulic pump  52  and flows  54   b  to a pressure regulator valve  58 . Pressure regulator valve  58  insures that the fluid pressure throughout the industrial transmission fluid system is maintained at an appropriate pressure to operate the transmission and compensates for wear in the pump. Also, another flow  54   c , between the strainer  56  and pressure regulator valve  58 , is provided for pump priming. In this bypass circuit, the fluid continues to flow  54   d  from the pressure regulator valve  22  through the torque converter  20  and through the transmission  22  and finally flows  54   g  to the sump  36 . Additionally, the present invention preferably includes a fluid flow  54   e  from the transmission  22  to a cooler  24  (FIG.  4 ), such as a radiator or fan, for cooling the fluid. Cooler  24  insures that the fluid is maintained at a desired operating temperature. 
     When the throttle/clutch variable controller  28  (FIG. 1) is moved to the first position, the transmission  22  is engaged through second coupler  32 , such as a cable/lever combination, that changes the position of directional flow valve  60 . Directional control valve  60  is connected in parallel to the fluid flow system within the industrial transmission, and is preferably mounted within the housing  34 . And hydraulic flow  20   d  occurs from the pressure regulator valve  22  to the directional flow valve  23 . The change of position of the directional flow valve  60  initiates another flow  54   f  of fluid to clutch assembly  42 , thereby causing the compression of clutch and friction plates that lock together and engage transmission output shaft  24 . As such, the power from driving engine  12  is multiplied by the torque converter  20  and transferred to the transmission output shaft  24  by the clutch assembly  42 . Increased power and torque is then transferred by further incrementing the variable controller  28 , which adjusts the throttle to increase the speed of the driving engine  12 . The transmission output shaft  24  is then disengaged by incrementing the variable controller  28  back to the idle or neutral position, which changes the position of the direction flow valve  60  to cut off the fluid flow  54   f  to the clutch assembly  42 . 
     Additionally, referring to FIG. 5, the transmission housing  34  further includes a case  64  having a top cover  66  that forms a chamber that houses the directional flow valve  60 . Attached to the case  64  at one end is a bell housing  68  that houses the torque converter  20  and attaches to the driving engine  12 . The bell housing  68  sealingly mounts the transmission  22  to the driving engine  12  so as to contain the fluid  37  within the housing  34 . The bell housing  68  may include an adapter plate for mounting the transmission  22  to the driving engine  12 . For example, the bell housing  68  may include a Society of Automotive Engineers mounting in sizes 1 to 5. Also, the transmission output shaft  24  may include a keyway  70  for holding a key  72  to secure a bushing or pulley  74 , for example, to the transmission output shaft. The transmission output shaft  24  is rotatably supported within the case  64  by shaft support member  40 , such as a bearing assembly. Additionally, an output shaft seal  76  and a seal retainer  78  are fitted between the case  64  and the transmission output shaft  24  to seal the fluid  37  within the housing  34 . 
     The directional flow valve of FIG. 5 has a clutch-engaging position and a neutral position. Other directional valves may be used that have additional positions, for example, to enable a reverse drive of the transmission output shaft  24 . Similarly, the clutch assembly  42  may include additional plates and gears to enable variable speed drive and reverse drive. 
     Although the industrial transmission has been described and illustrated in detail, it is to be clearly understood that the same is intended by way of illustration and example only and is not to be taken by way of limitation. For example, the transmission may be provided with a reverse gear or additional forward gears. The housing may comprise aluminum, steel, iron and other similar materials that may be machined, cast and otherwise formed with known manufacturing techniques. Also, the hydraulic pump may include a gear, vane, rotor, and piston pump or other similar pump. Further, the number and size of the clutch plates may vary depending on the horsepower rating of the drive engine. These plates may be available as off the shelf parts or specially manufactured for use with particular industrial applications of the transmission. Also, the shift lever may be engaged via a button on the throttle lever, the button being engageable only at engine idle speed. The auxiliary drive may be adapted for driving an external driven device that may be mounted to the housing of the industrial transmission. For example, a hydraulic pump may operate via the auxiliary drive to power a feed system, conveyor, lift arm, a lift cylinder on a wood chipper, or to provide hydraulic pressure to serve other purposes, or simply to turn an additional shaft, such as to operate a second wood chipper. Accordingly, variations and modifications of the industrial transmission will be apparent to one skilled in the art and the following claims are intended to cover all such modifications and equivalents.