US2943502A - Apparatus for the synchronizing and shifting of rotating shiftable toothed elements - Google Patents

Description

PERKINS ET AL 2,943,502

July 5, 1960 c. M.

APPARATUS FOR THE SYNCHRONIZING AND SHIFTING OF ROTATING SHIFTABLE TOOTHED ELEMENTS p 17 Sheets-Sheet 1 Filed March 5, 1956 ww M 74W".

ATTORNEYS y 1960 c. M. PERKINS, ETAL 2,943,502

APPARATUS FOR THE SYNCHRONIZING AND SHIFTING OF ROTATING SHIFTABLE TOOTHED ELEMENTS l7 Sheets-Sheet 4 Filed March 5, 1956 h\N ANN INVENTORS Own [5 M. PiR/(l/VS BY 77/0/ 075 1 Ma-NQM/WFH Arron/2Y5 R mw July 5, 1960 Filed March 5, 1956 c. M. PERKINS ETAL 2,943,502 APPARATUS FOR THE SYNCHR ROTATING SHIFTABL ONIZING AND SHIFTING OF E TOOTHED ELEMENTS 1'7 Sheets-Sheet 5 HTWRAE'YS July 5, 1960 c. M. PERKINS ETAL 2,943,502

APPARATUS FOR THE SYNCHRONIZING AND SHIFTING 0F ROTATING SHIFTABLE TOOTHED ELEMENTS Filed March 5, 1956 17 Sheets-Sheet 6 ETTORNZ'YS July 5, 1960 Filed March 5, 1956 M. PERKINS ETAL 2,943,502

C. APPARATUS FOR THE SYNCHRONIZING AND SHIFTING OF ROTATING SHIFTABLE TOOTHED ELEMENTS 17 Sheets-Sheet 7 INVENTORS CHHRLZS M Paw/N5 ATTORNEYS July 5, 1960 c. M. PERKINS ETAL 2,943,502 APPARATUS FOR THE SYNCHRONIZING AND SHIFTING OF ROTATING SHIFTABLE TOOTHED ELEMENTS Filed March 5, 1956 '17 Sheets-Sheet 8 HTTURNZ'YS y 1960 c M. PERKINS ETAL 2,943,502

APPARATUS FOR IHE SYNCHRONIZING AND SHIFTING OF ROTATING SHIFTABLE TOOTHED ELEMENTS Filed March 5, 1956 17 Sheets-Sheet 9 2/4; 3 226 2 e7 72 as? Arron/5 Y5 July 5, 1960 M PERKINS EI'AL 2,943,502

C. APPARATUS FOR THE SYNCHRONIZING AND SHIFTING OF ROTATING SHIF'TABLE TOOTHED ELEMENTS Filed March 5, 1956 17 Sheets-Sheet 10 INVENTORS (HR/P4 4': M. Pun/vs July 5, 1960 c, ms ETAL 2,943,502

APPARATUS FOR THE SYNCHRONIZING AND SHIFTING OF ROTATING SHIFTABLE TOOTHED ELEMENTS Filed March 5, 1956 1'7 Sheets-Sheet 11 INVENT0R$ 0mm :5 A1. Pam/v5 July 5, 1960 c. M. PERKINS ETAL APPARATUS FOR THE SYNCHRONIZING AND SHIFTING OF ROTATING SHIFTABLE TOOTHED ELEMENTS l7 Sheets-Sheet 12 Filed March 5, 1956 y 1960 c. M. PERKINS ETAL 2,943,502

APPARATUS FOR THE SYNCHRONIZING AND SHIFTING OF ROTATING SHIFTABLE TOOTHED ELEMENTS 17 Sheets-Sheet 13 Filed March 5, 1956 INVENTORS CHE/FLA! M. Paw/N5 Two/m: K Maw/ 4mm ATTORNEYS c. M. PERKINS ETAL 2,943,502 APPARATUS FOR THE SYNCHRONIZING AND SHIFTING 0F ROTATING SHIFTABLE TOOTHED ELEMENTS July 5, 1960 17 Sheets-Sheet 14 Filed March 5, 1956 NH QM IN V EN TORS [H/ML [5 A4. Paw/N5 HTTQRNEYS WWN y 1950 M. PERKINS ET AL 2,943,502

C. APPARATUS FOR THE SYNCHRONIZING AND, SHIFTiNG OF ROTATING SHIFTABLE TOOTHED ELEMENTS Filed March 5, 1956 17 Sheets-Sheet 15 wmozam W '1 74 m ATTORNEYS y 1950 c. M. PERKINS ET AL 2,943,502

APPARATUS FOR THE SYNCHRONIZING AND SHIFTING 0F ROTATING SHIFTABLE TOOTHED ELEMENTS l7 Sheets-Sheet 16 Filed March 5, 1956 July 5, 1960 c. M. PERKINS ET AL 2,943,502

* APPARATUS FOR THE SYNCHRONIZING AND SHIFTING OF ROTATING SHIFTABLE TOOTHED ELEMENTS Filed March 5, 1956 17 Sheets-Sheet 17 4g- 25 INVENTORS CHHRLES n1. Paw/vs Z/gzz H TTORNEYS Unit tats

APPARATUS FOR THE SYNCHRONIZING AND SHIFTING OF ROTA'I'ING SHIFTABLE TOOTHED ELEMENTS Filed Mar. 5, 1956, Ser. No. 569,503

57 Claims. (Cl. 74-339) This invention relates to a method and apparatus for the synchronizing of the speeds, and shifting, of shiftable rotating toothed elements.

In carrying out a program of steadily improving the design of transmission devices, it is a constant objective to continually reduce both the skill and the effort required of the operator in carrying out a shifting operation. This is a constant objective regardless of the particular service involved, whether for passenger automobile use, commercial vehicle'use including heavy trucks, in earth moving equipment, cranes, mining machinery, or in any of the many other situations wherein shiftable gearing is utilized. Particularly in transmissions for heavy duty use, such as in heavy trucks or earth moving equipment, it is desirable to reduce as much as possible the skill and effort required of the driver in effecting a shift. On

the other hand, presently available fully automatic trans missions havenot been entirely acceptable for certain uses, especially heavy duty because oftheir high original cost, their difiicult and expensive maintenance requirements and their relative inflexibility to meet varying operating conditions.

Therefore, it has long been desirable to provide for said certain uses, such as over-the-road operations, a power operated transmission whose shifting is subject to easy manual selection, said selection being capable of being made by any of a variety of devices chosen to fit given operating conditions, as a push-pull rod, selectable push buttons or other convenient devices.

Further, recognizing the demand in connection with other uses, such, as in trucks designed to operate in congested trafiic, for fully automatic shifting operations, and the probable spreading of the demand therefor, it is equally desirable to provide a transmission capable of manual selection as above mentioned but which is of such basic design that it can be readily adapted to fully automatic control if and when desired by the simple addition of suitable controlling devices.

Turning now to the making of certain definitions, for the purpose of clarity in discussion but with no intention to limit, it is known that transmissions commonly employ a series of relatively shiftable, rotating, meshable members which are adapted to selectively mesh to provide the desired ratio between the speed of rotation of the input shaft of the transmission and the output shaft thereof. These members may be gears, jaw clutch parts, or other interengaging mechanical members, and will be hereinafter collectively referred to as toothed elements. The term shifting and derivatives thereof shall refer to the act of moving one or more of the toothed elements into meshing engagement with other toothed, elements to obtain a desired speed ratio between the input and output shafts of the transmission. To obtain a meshing of a pair of the rotating toothedelements, it is desirable n ed-1 2 .1.1960

2 I when they are rotating at such relative; speedsthat thejr respective pitch circles, or corresponding parts, are travel; ing at precisely the same circumferential rates, 'Ifhe proc; ess of bringing these rotating toothed elements to he meshed to such relative speeds (if-rotation shall behereinafter referred to as synchronizing, The term con; dition of synchronization as used hereinaftershall; refer to a relative speed condition of the toothed elements which may or may not bea condition ofj exact syn; chronization. The term acceptable condition of jsynchronization as used hereinafter shall refer to any con; dition of relative speeds of the toothed elerrrents whieh will permit their meshing without excessive or unreasonas ble clashing.

One h mos r t antrb t no mean hacnly problem involved in providing a transmission for heavy duty operation, whether manually or: automatically controlled, is the problem of obtaining an acceptable condition of synchronization of the toothed elements at the moment of effecting a shift. In a transmission intended for heavy duty operation, the toothed elements, shafts and other rotating parts involved are large andt'hereby possessed of considerable inertia, This maltesthe'prohlem of synchronizing them during the process offs ifting materially more difiicult, and by the same token"e,ven more important, than the corresponding problem in Y missions intended for lighter duty, such as; in passe automobiles.

In the usual approach to transmission synchronization, means are provided which are actuated at the instant; of exact synchronization and the toothed elements/lobe meshed are then moved as rapidly asfpossible into meshing engagement with each other, the object beingltgeffect such engagement as close as possible to the instant of exact synchronization of the toothed elements to be meshed; This is satisfactory where a slight amount of time is permissible for accelerating or decelerating the toothed elements being driven by the input shaft during the shifting operation to bring them into, an accept ble condition of synchronization with the mating tooled elements connected to the output shaft so that such are celerating and decelerating occurs at a relatively slow rate. However, in any type of operation where a large amount of, horsepower is being conducted through the transmission, as in a heavy truck, climbing afmountain grade, it is desirable to have the input shaft and output shaft of" the transmission disconnected for as, period as possible and this requires. a substantial s ing of the" rate of such accelerating and decelerating. Thus, in order to speed the deceleration, of therotating parts driven by the input shaft during an upshift, it as become customary to use a deceleration, brake, I however, the rate of change of, speed becomesjso rap that where shifting is started only upon exact synchroi i i t' tion of the toothed elements to be, meshed, it is entirely possible for the meshable toothed elements. to. b entirely out of an acceptable condition of synchroni even during the fraction of a second required forthe gears to move in response to the initiation of the; sh fting sequence. Previous efforts to avoid this diflicuity have, insofar as We are aware, been primarily dire ted toward increasing the speed at which the toothed elements are moved toward each other upon the. attainment of exact synchronization.

The present invention, however, approaches the. problem by detecting a particular condition of synchronization slightly before, that is, in-anticipation of, exact synchronization and initiating the shifting movement at that time, the amount of such anticipation being chosen in a given situation to cause the meshable toothedelments to enter into meshable engagement with each other'suhstantially at, or slightly ahead of, the instant of exact synchronizaion of the speeds of rotation thereof.

A further problem with conventional equipment has been the problem arising out of disconnecting the engine from the input end of the transmission by the conventional operation of the clutch. With conventional equipment, this is necessary in order to enable the transmission synchronizers to change the speed of the toothed element on the engine side of any given pair of toothed elements to be engaged sufiiciently to enable such pair to attain an acceptable condition of synchronization, it being evident that the motion of the vehicle will keep the proipeller shaft operating at a speed during any ordinary shifting sequence which is not within the drivers control. Thus, unless the engine speed is increased or decreased sutficiently accurately to correspond to the change in speedof the input end of the transmission brought about by the shifting operation, either a great load will be placed upon the clutch when it re-engages 'or an excessive load will be placed upon the transmission parts. In an upshift, this is not too serious since if the accelerator is merely released the engine speed will diminish and thus it will change its speed in the same direction as that which re-engagement of the clutch will bring about.

,However, in a downshift, this is not true and unless the accelerator is accurately controlled to increase the engine speed by the proper amount, serious shock loads can occur.

Thus, by providing a system wherein the clutch can .remain engaged throughout the'portion of a shifting operation comprising movement from neutral to a shifted position, it becomes possible not only to effect a more stantially greater strain on the parts. On the other hand,

if the interengagement of the shiftable parts can be made while the toothed element speeds are approaching exact synchronization, then engagement of the toothed elements will assist synchronization.

Therefore, it is desirable to provide an apparatus, applicable to both manual and automatic shifting devices, which will anticipate the instant of exact synchronizajti'on "of the-toothed elements being meshed s'ufiiciently 'fthat by the time the shifting mechanism operates and actually brings the toothed elements into meshing engagement with each other, their speeds will be in substantially exact synchronization, rather than in some indefinite condition not close to exact synchronization. Further, since eifecting a shift exactly at the instant of exact synchronization for all conditions of operation is impossible as a practical matter, it is desirable to provide means anticipating the instant of exact synchronization 'and initiating a shifting operation a sufiicient period of time prior thereto that the meshing'engagement of the toothed elements being shifted will occur slightly before the point of exact synchronization. Thus, at the moment of engagement of the toothed elements, their relative speeds will be approaching exact synchronization rather than, as in present practice, moving away from exact synchronization.

A still further problem involved in heavy duty transmissions is that when manual shifting is carried out, the shift is often relatively slow because of the limited force available from the operators hand to effect the shifting. In an operation involving the delivery of a large amount rapid shift, particularly in a downshift sequence, as 1 above set forth but it also becomes possible to do so withof horsepower, such as where a heavy truck is climbing uphill, it is highly essential that the interruption of the delivery of the power from the engine to the wheels be held to the shortest possible time interval. Thus, although fully automatic devices for elfecting such shifting are not desirable since they are not usually sufi'rciently flexible to meet the varying load conditions imposed upon heavy duty equipment, a manually shifted device does not ordinarily operate rapidly enough to prevent the engine shaft and the propeller shaft from being disconnected for an undesirablylong period of time. Accordingly, it is desirable to provide an apparatus which will be completely under manual control for each stage of its operation but wherein the. operation itself is carried out under power so that it will be completed with a minimum period of-time whereinthe engine shaft is disconnected irom the propeller shaft.

While primary reference has thus far been, and will herein continue to be, made to heavy duty use, which for present purposes may be considered to be all vehicular transmissions other than those for passenger cars, and including earth moving equipment, cranes, mining machinery, and similar equipment, and the research efforts resulting in the present invention have had in mind primarily heavy duty use, it should be clearly borne in mind that many of the problems solved by the present invention are also presentin passenger car use. Hence, many. of the objects of the invention can be carried out in passenger car applications and the scope of the invention should be interpreted accordingly.

Likewise, while one primary purpose has been to provide a system of transmission control which provides manual selection and power shifting, it will be understood that some of the; units developed for use with and in such system, particularly including the synchronizing method and apparatus but not .limited thereto, are also applicable to and advantageous in other types of transmissions including an automatic transmissiom'and the portions of'the invention relating to such units shall be understood accordingly.

A major object of the invention is to provide a transmission shifting device wherein all shifting operations will be subject to manual selection but will be eflfected by power.

A further object of the invention is to provide a device, as aforesaid, wherein the manual control requires relatively little skill or effort on the part of the operator.

A further object of the invention is to provide a device, as aforesaid, in which the manual control may be moved into a desired position and then left in that position without waiting for the shifting operation to be completed, and the apparatus will then automatically complete the shifting operation without further attention on the part ofthe operator, excepting only that in a downshift operation the operator must increase the engine speed sufliciently to make synchronization of the gears possible.

A further object of the invention is to provide a. shifting system subject to manual control but carrying out the shifting operation under power, which system will be adaptable for a use with a variety of difierent specific sources of power.

tuselfecting the shifting and will bring the toothed elements being shifted into engagement with each other at a' point slightly ahead of the instant of exact synchronization.

A further object of the invention is to provide a device of thegeneral type, as aforesaid, which will anticipate the instant of exact synchronization of the toothed elements being shifted and will initiate such shifting at a point sufliciently prior to the instant of exact synchronization that said elements will become i-nterengaged substantially at the instant of exact synchronization.

A further object of the invention is to provide a device, as aforesaid, wherein the time period by which the instant of exact synchronization will be anticipated by the apparatus initiating the shifting will be the same for each of the available speed ratios of the transmission.

A further object of the invention is to provide a device, 'as aforesaid, which will automatically accommodate itself to either an upshift or a downshift and anticipate exact synchronization in either case.

A further object of the invention is to provide a device which will be operable by a single, easily moved control which will require the operators hand to be away from the other controls of the machine involved 'a minimum period of time or which may, if desired, be adapted for operation by the operator without requiring his hand to move from the other controls at all.

A further object of the invention is to provide a device, as aforesaid, which will be extremely rapid in operation and thereby effect shifting smoothly and with a minimum period of time during which the power from the engine to the propeller shaft is interrupted.

A further object of the invention is to provide a device, as aforesaid, in which the engine will remain connected to certain parts of the transmission throughout the portion of a downshift shifting operation extending from the time the transmission parts are put into neutral 'condition during the shift from the upper to the lower setting until the transmission parts reach their completely shifted position whereby the engine may be utilized for changing the speed of the parts remaining so connected and thereby eliminate the shock to the driving system which sometimes otherwise occurs upon the engagement of a previously released clutch. In prior practice such a previously released clutch sometimes permitted the engine and the propeller shaft driving parts of the transposition from any shifted position, which mechanism involves only a single pressure fluid cylinder.

A further object of the invention'is to provide pressure fluid shifting apparatus for a transmission in which pressure fliiid may be applied to the apparatus for eflfecting the next shift to be made and including shift preventing means preventing engagement of the toothed elements in response to said pressure until the toothed elements to be engaged have reached a predetermined condition of synchronization.

A further object of the invention is to provide apparatus in which said shift preventing means and the means returning the 'main transmission to its neutral position during each shifting operation are the same apparatus.

It is a further object ofthe invention to provide a device wherein the next shifting operation is 'pre-energi zed but the shifting movement is blocked until the toothed elements to be engaged have reached a desirable and predetermined condition of synchronization. When such condition is reached, the blocking condition is removed and the parts will then move with a minimum time requirement into the next shifted position.

"A furtherobject of the invention is to provide a method, as aforesaid, which can be carried out by a variety of different typesofapparatus, particularly'prcssure fluid apparatus or electrical apparatus, as desired,

- to meet the requirements of a particular operation.

A further object of the invention is to provide a method for effecting shifting of a transmission which can be carriedout 'by relatively simple apparatus.

A further object of the invention is to provide apparatus of the type aforesaid which will be positive and reliable in operation, which will be rugged, and which will not require excessive maintenance.

A further object of the invention is to provide a transmission of the general type aforesaid wherein the parts carrying the heavy load are relatively simple and of well known nature and the parts most likely to require maintenance are relatively small and can, if necessary, be readily removed and replaced bodily.

A further object of the invention is to provide apparatus of the type aforesaid which'can be readily serviced by mechanics of ordinary ability and, at least for the most part, by the use of ordinary tools.

A further object of the invention is to provide a device, as aforesaid, wherein the specially made parts are all relatively easy to fabricate and thereby economical to manufacture.

Other objects and purposes of the invention will become apparent to persons acquainted with this general type of apparatus upon reading the following specification and examining the accompanying drawings.

in the drawings:

Figure 1 is a schematic representation of a fluid energized form of apparatus embodying the invention and representing same in its neutral condition.

Figure 2 is a central cross sectional view of a detector unit adapted for utilization with the apparatus shown in Figure 1.

Figure 2a shows a tooth pattern provided between certain of the parts shown in Figure 2, and is a sectional view taken on line lla lIa of Figure 2.v

Figure 3 is a sectional view taken on the line III III of Figure 2. Y

Figure 4 is a schematic representation similar to Figure 1 and showing the apparatus in the position corresponding to the commencement of a shift out of neutral position and into first gear.

Figure Sis a representation similar to a portion of Figure 4 and showing such portion of the -apparatus after the manual trip valve has been actuated incident t0 the Shift from neutral to, fiISt gear by moving the control rod for the control valve into first gear position.

Figure 6 is a representation similar to Figure 1 and showing the apparatus with the shift into first gear completed.

Figure 7 is a representation similar to Figure l and showing the apparatus in a condition as it is shifted from first gear position to second gear position wherein the control rod is in intermediate position between first gear position and second gear position.

Figure 8 is a representation similar to Figure 1 and showing the control rod in second gear position and the transmission parts partially moved out of first gear position toward neutral as the shift from first gear to second gear progresses.

Figure 9 is a representation similar to Figure 1 and showing the transmission parts returned to full neutral position as they move from first gear to second gear position.

Figure 10 is a representation similar to a portion of Figure 8 and showing the position of the Pats of the detector unit after the toothed elements therewitbin have shifted to their second gear position but prior to movement of any of the parts associated with the main transmission toward second gear.

Figure 11 is a representation similar to Figure -1 and

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