MXPA98007421A - Set of retain of riel de cam - Google Patents

Abstract

The present invention relates to a transmission system (10), comprising a master friction clutch (14) for coupling by drive a motor (12) to a composite mechanical transmission (16) that includes a main section and an auxiliary section , a change element (150, 176) for moving a positive clutch element (151A) selected in said main section to a selected one of a linked position and an unlinked position and independent means (120, 146) of operation of said element of clutch and said master friction clutch to detect a requirement to move said positive clutch element from said position linked to said disengaged position and to provide a signal of intention to change indicative thereof, said system characterized by: a detent mechanism ( 156/172, 186/196) to provide a resistance selectively variable to the movement of said clutch element from said linked position. aa said disengaged position, said detent mechanism having a first condition to provide a greater resistance to the movement of said clutch element of said position linked to said disengaged position and a second condition to apply a lower resistance to the movement of said clutch member of said clutch member. said position linked to said unlinked position, said retainer mechanism assuming said second condition upon detecting said signal of intent to change

Description

SET OF RETAINING CHAIN OF CHANGE Field of the Invention The present invention relates to gear rail retainer mechanisms for providing selectively variable resistance to axial or rotary movement of a change rail to minimize the occurrence of out-of-round jumps. In a particular preferred embodiment, the present invention relates to a detent mechanism for a lever shift transmission system having means for determining a driver's intention to initiate a lever change and, upon sensing this intention, causing the detent mechanism provides a decreased resistance to the movement of the shift rail. Description of the State of the Art The transmissions of manual shift vehicles of the simple and / or compound types and of the synchronized, blocked and / or unsynchronized types are well known in the prior art, as it can be seen referring to the patents of the United States Nos. 5,000,060 and 5,390,561, which are incorporated herein by reference. Prior art manual gear transmissions, especially those used for heavy duty vehicles such as straight trucks and conventional trailers / semi-trailers (ie without cab on the engine), used a manual shift lever extending upwardly from a gearbox subassembly mounted directly on the transmission housing and interacted with a single or multiple rail shifting change mechanism of the types illustrated in U.S. Patents Nos. 4,455,883; 4,550,627; 4,920,815; and 5,272,931, which are incorporated herein by reference. Although these broadcasts are widely used and commercially successful, they are not entirely satisfactory, since under certain severe road conditions, transmissions may experience jumps induced by the shift lever (ie, the unintentional disengagement of an exchange relationship). This situation is usually associated with transmissions used in relatively heavy duty vehicles (ie as MVMA Class 5 and larger vehicles), which tend to have relatively long shift levers that have relatively large shift knobs, which often include master valves to control the limit and / or changes of the splitter, at its ends. As is known in the prior art, shift rail detent mechanisms are used to keep the shift rails in a fixed position to resist jumps, such as the jumps induced by the shift lever. Examples of these retainer mechanisms can be seen in U.S. Patents 4,550,627; 4,614,126; 4,920,815; 5,000,060; and 5,350,561, which are incorporated herein by reference. These mechanisms are not entirely satisfactory, since the amount of resistance to movement of the shifting rail needed to provide significant jump resistance often increases the operator effort associated with a shifting lever. Partially automated mechanical transmission systems that provide automatic assistance, such as automatic engine fuel control, for manual lever shift transmissions are known in the prior art, as can be seen in U.S. Patents 4,593,580; ,569,115; 5,571,059; 5,573,477; and 5,582,558, which are incorporated herein by reference, and co-pending US Patent Applications Nos. Nos. 08 / 649,829, 08 / 649,830, 08 / 649,831 and 08 / 666,164, all assigned to Eaton Corporation, the assignee. of the present application. These systems use automatic engine fuel controls and / or range and / or starter shift actuators, driven by an indication of the driver of an attempt to make a change, allowing an old change to be unlinked and a new change to be engaged. target without requiring the driver to manipulate the clutch pedal (required only for starting and stopping the vehicle) or the throttle pedal. SUMMARY OF THE INVENTION According to a preferred embodiment of the present invention, the disadvantages of the prior art are minimized or solved by the provision of a selectively variable detent mechanism for a transmission system having a means to detect a driver's intention to initiate a lever change, which provides significant resistance to the shift-induced leap without objectionably increasing the effort required to effect a desired change with the lever. The foregoing is achieved by providing a stopping mechanism that can be controlled to a first condition to provide greater resistance to the movement of the shifting rail or to a second condition to provide less resistance to the movement of the shifting rail. In determining the intention of a driver to initiate a lever change, and preferably to confirm the engagement of a desired gear ratio, the catch mechanism assumes the second condition where the resistance of the detent to the movement of the shift rail is minimized (and , in this way to the lever changes). When not in the initiation of a lever shift operation or during the same, the catch mechanism assumes the first condition where a significant retainer resistance is applied to the movement of the shift rail (and, consequently, to the jump induced shift lever). Accordingly, an object of the present invention is to provide a new and improved gear rail retainer mechanism for mechanical transmission systems. This and other purposes and advantages of the present invention will be apparent on the basis of reading the following description of the preferred embodiment taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a symbolic representation of a vehicular drive line using the improved change rail retainer assembly of the present invention. Figure 2 is a symbolic illustration of the parameters that affect the jump torque induced by the shift lever. Figure 3 is a symbolic illustration of the parameters that affect the torsion of the retainer. Figures 4A-4C are symbolic representations of a manually operated, manually assisted, heavy-duty transmission system of the type that the present invention uses in its entirety. Figures 5 and 6 are schematic illustrations of alternate variable resistance gear rail retainer mechanisms. Description of the Preferred Embodiment Form Certain terminology will be used in the following description of the preferred embodiment, for convenience only and not by way of limitation. The terms "upward" (up), "do nward" (downward), "right ard" (on the right) and "leftward" (on the left) will designate the directions in the drawings to which reference is made. The terms "forward" and "rearward" will refer, respectively, to the front and rear ends of the drive train components as they are conventionally mounted on the vehicle, being respectively left and right sides of the various components of the drive train, as illustrated in figure 1. The terms "clockwise" (clockwise) and "counterclock ise" (counterclockwise) refer to rotary directions as visualize from the left side of the vehicle, as illustrated in figure 1. This terminology includes the words mentioned specifically above, derived from them and words of similar importance. The preferred embodiment of the present invention is illustrated used in a partially automated, lever-shifted mechanical transmission system of the type illustrated in the aforementioned U.S. Patent Nos. 4,593,580; 5,569,115; and 5,582,558, and in the aforementioned co-pending United States patent application Serial No. 08 /, entitled MECHANICAL TRANSMISSION SYSTEM FOR LEVER CHANGES PARTIALLY AUTOMATED. Although the present invention is used in a particularly advantageous manner in these systems, its application is not limited thereto. A typical power train system 10 for vehicles that advantageously uses the present invention can be seen with reference to Figure 1. Power train 10 is of the type commonly used in heavy duty vehicles, such as conventional tractors of tractor vehicles / semi-trailer, and includes a motor, typically a diesel engine, 12, a master friction clutch 14 contained within a clutch housing, a multi-speed composite transmission 16, and a drive shaft assembly 18. The transmission 16 it includes an output shaft 20 coupled by drive to a drive shaft 22 of a vehicle by a universal joint 24 for driving the drive shaft assembly, as is known in the prior art. The transmission 16 is housed within a transmission housing 26 to which the shift tower 28 of the shift lever assembly 30 is directly mounted. Figure 4A illustrates a shift mode for manual assisted changes of a combined composite transmission of the transmission. type limit and splitter that is subject to changes manually by a lever of change. Briefly, the shift lever 31 is movable in the side-by-side or X-X direction to select a particular relationship or relationships to be linked and is movable in the bow-and-aft direction or Y-Y to selectively link and de-link various gear ratios. The change diagram may include a feature of automatic limit changes and selected splitter changes, as is known in the prior art. Manual transmissions using change mechanisms and change diagrams of this type are well known in the prior art and can be seen in greater detail by reference to the aforementioned US Patents Nos. 5,000,060 and 5,390,561. Typically, the shift lever assembly 30 includes a shift finger or the like (not shown) that extends downwardly in a shift mechanism 32, such as a multi-track shift bar housing assembly or an axle assembly. of simple changes, as is well known in the prior art and as illustrated in the aforementioned US Patents Nos. 4,455,883; 4,550,627; 4,920,815; Y ,272, 931. In prior art transmissions of the general type illustrated in Figure 1 but not incorporating the improved gear rail retainer assembly of the present invention, it is known that shift gears can take place if road conditions are severe. Briefly, the leap of the shift lever is the unintentional uncoupling of the jaw clutches from a manual shift transmission caused by shifter oscillations in the Y-Y direction around the Y-Y axis of rotation of the shift lever assembly. The purpose of the change rail retainer assembly of the present invention is to minimize the occurrences of these shift-induced jumps while the change effort is not objectionably increased. In a typical heavy duty vehicle power train, the engine-clutch-transmission assembly will tend to move, during severe road conditions, in a vertical fashion (as illustrated by arrow 36) and rotatably around a turning point or axis 38 (usually located in the clutch area of the vehicle). As indicated by arrow 40, an upward movement of the assembly is almost always associated with an anti-clockwise rotation of the assembly about the axis of rotation 38 while, as indicated by arrow 42, a downward movement of the assembly is almost always accompanied by a clockwise rotation of the assembly about the axis of rotation 38. As will be understood, the lever-induced jumps of changes are forced by the inertial effects of excessive vibration induced by the path in the drive train of the vehicle. This shock induced by the path causes the motor-clutch-transmission assembly to pitch on its mounts, as illustrated in figure 1. This pitch occurs at the natural frequency of the engine-clutch-transmission-saddle system, usually between approximately 7 and 10 Hz . This pitch includes relatively high vertical, longitudinal and rotary accelerations on the transmission and, in particular, the shift lever assembly. The shift lever assembly then develops an inertial jump torsion Tj about its pivot 34 as determined by the sum of the inertial torques thereon, as will be described in more detail below and as schematically illustrated in Fig. 2. It should be noted that the typical backward deviation in the transmission lever tends to increase the jump torsion. As will be described in more detail below and illustrated schematically in Figure 3, the jump torque Tj is resisted by the force of the shift rail retainer or shift shaft multiplied by its moment arm determined by the distance between the pivot 34 and the rail or shift shaft (ie, detent torsion T0). The detent force may include the forces required to bridge a detent mechanism, twist lock in the engaged jaw clutches, and frictional forces in the shift mechanism. When the jump torsion exceeds the detent torque, the leap in the shift lever takes place. This tends to happen when the drive train has a very low torque, such as inertial running conditions of the vehicle, since the friction of the so-called torsion lock in the drive train during driving conditions tends to lock the elements of clutch linked gliders that are hooked and greatly exceeds any jump force imposed on them. Since the shift lever assembly 30 itself is a dynamic system, it has its own natural frequency. Unfortunately, this also usually occurs between 7 and 10 Hz. This frequency is determined by the height of the lever, the deviation of the lever, the height of the tower and the stiffness of the insulator. If the natural frequency of the motor-clutch-transmission assembly corresponds to that of the shift lever assembly, the jump propensity is greater since the inertial forces amplified by the motor are further amplified by the lever resonance. In Figure 2 Tj = axMy - a? Mx + I where: Tj = jump torque M = Lever mass I = Moment of inertia of the lever ax = Longitudinal acceleration a? = Vertical acceleration c¿ = Angular acceleration of the lever X = Distance between cg of the lever and pivot Y = Vertical distance between cg of the lever and pivot cg = center of gravity while in figure 3, T0 = Fxd where: T0 = Retaining torsion Fx = Retaining force d = Distance between pivot and rail Figure 2 illustrates a mathematical model for calculating the jump torsion Tj induced in a change rail by the whip of the lever changes It should be noted that the jump torque will be applied in the anti-clockwise and clockwise directions around the axis of rotation of the shift lever 34 but will tend to cause jumps in only one of those two directions, depending on the gear ratio linked in that moment. One method to minimize the shift-induced jump is to increase the catch force Fx so that the detent torque almost always exceeds the jump torque. Unfortunately, this increased retaining force, if not relieved at the time of the change, will result in an objectionably high change effort. In a preferred embodiment of the present invention, the forward shift of the transmission 16, comprising the main section 16A coupled to the auxiliary section 16B, is implemented / assisted semi-automatically by the semi-automatic transmission system of the vehicle 100, illustrated in FIG. Figures 4A-4C. The main section 16A includes an input shaft 50, which is operatively coupled, commonly by means of a drive shaft, to the driving wheels of the vehicle. The auxiliary section 16B is of the splitter type, preferably of the combined limiter and splitter type, as illustrated in U.S. Patent No. 5,390,561. The gear ratios available from the main transmission section 16 can be manually selected by placing the shift lever 31 according to the prescribed shift diagram to link the desired particular gear ratio of the main section 16 A. As will be described, no manipulation of the master clutch is required (apart from when the vehicle is brought to a standstill condition or when it is released from it) or manual synchronization. The system includes means to signal an attempt to make a change to an objective relationship and will automatically take actions to minimize or alleviate the torsional lock conditions, allowing, if required, an easier change in the neutral main section from the relationship of linked main section, and also allowing the automatic and rapid termination of the required changes of the splitter when making a change to neutral. Upon detecting a neutral condition, the system will cause the motor to rotate at a substantially synchronous speed to be linked to a desired gear ratio. The system 100 includes sensors 106 for detecting the rotary speed of the motor (ES), 108 for detecting the rotational speed of the input shaft (IS), and 110 for detecting the rotational speed of the output shaft (OS) and providing signals indicative of the same. As is known, with the clutch 14 engaged and the transmission in a known gear ratio, ES = IS = OS * GR (see U.S. Patent No. 4,361,060). The motor 12 is electronically controlled, including an electronic controller 112 that communicates via an electronic data link (DL) that operates under an industry standard protocol such as SAE J-1922, SAE J-1939, ISO 11898 or so. -lar. The throttle position (operator demand) is a desirable parameter for selecting the change points in another control logic. A separate throttle position sensor 113 can be provided or the throttle position (THL) can be detected from the data link. The gross motor torque (TEG) and the friction torque of the base motor (TBEF) can also be obtained from the data link. A manual clutch pedal 115 controls the main clutch, and a sensor 114 provides a signal (CL) indicative of the linked or unlinked clutch condition. The condition of the clutch can also be determined by comparing the speed of the motor with the speed of the input shaft. A splitter driver 116 is provided to operate the split section clutch (not illustrated) according to the output signals of the command.

The shift lever 31 has a knob 118 which contains a selector key 120 by means of which the intention to effect a change by the driver can be detected. A preferred embodiment of selector key 120 can be seen with reference to Figures 4A-4C. The key 120 includes a body 120 A in which there is an oscillating element 120B rotatably mounted. The oscillating element is spring-loaded to the centered, non-displaced position, which is illustrated. The operator can press the surface 120C or 120D of the oscillating element to make the oscillating key rotate in the direction of the arrows 120E or 120F, respectively, to select an upward or downward change, respectively. The oscillating element can move in the direction of the arrows and then release to provide a pulse "up" (up) or "down" (down) or can be carried to the positions "up" or "down" and retained in them, to achieve different control results, as will be described in more detail below. The oscillating element can be used to provide multiple pulses to request an alternative change (see United States Patent No. 4)., 648,290). Alternatively, the oscillating member 120B may be replaced by a sear, pressure sensitive surfaces, "up" and "down" buttons, or the like. A control display unit 124 for the driver includes a graphical representation of the six-position change diagram with individually illuminating display elements 126, 128, 130, 132, 134 and 136 representing each of the selectable linking positions. . Preferably, each half of the screen elements of change mode (ie, 128 A and 128B) may be illuminated individually, allowing the screen to inform the driver of the position of the lever and splitter for the linked and / or objective relationship. In a preferred embodiment, the linked relationship is lit uniformly, while the objective relationship is indicated by a scintillating light. The system includes a control unit 146, preferably a control unit based on a microprocessor of the type illustrated in U.S. Patents 4,595,986; 4,361,065 and 5,335,566, which are incorporated herein by reference, to receive input signals 148 and process them according to predetermined logic rules to emit command output signals 150 to the actuators of the system, such as the split-section actuator 116 , the motor controller 112 and the display unit 124. A separate system controller 146 can be used, or the ECU 112 communicating on an electronic data link can be used. As illustrated in co-pending US Patent Application Serial No. 08 / 597,304, the splitter driver 116 is preferably a three-position device, which allows a selectable and maintainable splitter section in neutral. Alternatively, a "pseudo" neutral splitter can be provided by de-energizing the splitter driver when the splitter clutch 80 is in an unlinked, intermediate position. Dynamic forward changes only from the splitter, other than those for the most fully automatic 9-10 and 10-9 splitter changes, are automatically implemented at the driver's request through the use of the 120 key switch. example, assuming a three-position splitter driver, upon detecting that a splitter change is required, receiving a single "up" signal when linked in first, third, fifth or seventh, or receiving a single "down" signal when is linked in second, fourth, sixth or octave, the ECU 146 will issue commands to the actuator 116 to push the actuator to neutral, and to the motor controller 112 to minimize or break the torque. This can be achieved by causing the motor to waver around a zero steering torsion value (see the aforementioned U.S. Patent No. 4,850,236). As soon as the splitter neutral is detected, the motor will be commanded at a substantially synchronous motor speed for the target change ratio at the current output shaft speed (ES = IS = OS * GRt ± ERR0R). The linkage is timed, in view of reaction times and velocities and accelerations of the shaft, to occur just outside the synchronous to prevent clutch knocking. Automatic splitter changes of this general type are illustrated in the aforementioned United States Patents 4,722,248 and 5,435,212. The most fully automated splitter changes 9-10 and 10-9 are implemented in the same way but are initiated by the ECU, not the selector key 120, according to predetermined change programs. The linked and neutral (unlinked) conditions of the transmission 10 can be detected by comparing the rotational speeds with known rates of change (IS / OS = GR ± = 1 a ± Y?) For a period of time. Position sensors can be used instead of speed logic of the input shaft and output shaft or in addition to it. When synchronized to link an objective relationship, the engine is steered to achieve and remain at a speed of approximately 30 to 100 RPM (preferably approximately 60 RPM) above or below (preferably below) the true synchronous velocity ( ESSYCHR0 = (OS x GRT) - 45 RPM) to obtain a good quality jaw clutch engagement without knocking. To verify the linkage of an objective relationship, the system makes the input shaft speed equal to the product of the output shaft speed and the numerical value of the target ratio, more or less approximately 10 to 30 RPM (IS = 0S * GRt) ± 20 RPM) for a period of time, approximately 100 to 400 milliseconds. The aforementioned logic allows to determine the linked and neutral transmission conditions based on the speeds of the input and output axis without false detection of linkage caused by the synchronization of the motor to link an objective relationship (see United States patent application co -Depending on Serial No. 08 / 790,210). When in an even-numbered relation (ie when in the high-splitter ratio) and a single upshift is required, an upshift of the lever (with downward shifting of the splitter) and the system is appropriate, if requested by the driver, will automatically assist in its implementation. Similarly, when it is in an odd number relationship (that is, when it is in the low splitter ratio) and a single downshift is required, a downward shift of the lever (with upshift of the splitter) and the system is appropriate, if the driver requests it, it will automatically assist in its implementation. It is noteworthy that in the system 100, the changes only of the splitter will be implemented automatically, while the changes of lever, with changes of accompanying splitter, require initiation by the driver and manipulation of the clutch clutch of the main section. When a combined change of lever and splitter is required, a single pulse of the selector in the proper direction (as opposed to keeping the oscillating element 120B in the corresponding offset position) is taken as simply a request for an appropriate splitter change without automatic assistance, and the splitter will be pre-selected to move to the appropriate splitter position and will do this when the operator moves manually to the neutral change or otherwise breaks the torsion. Then, the driver is required to link the appropriate main section ratio without intervention of the controller 148. This is substantially identical to the operation of a fully manual splitter type transmission. If the driver wishes automatic assistance for a combined change of lever and splitter, the oscillating element 120B of the selector is brought to the appropriate position and retained therein (for at least 50 milliseconds to 1 second) to request an assisted upward or downward shift. Controller 148, upon receiving this request, will automatically (for a period of approximately 2-5 seconds) the engine be supplied with fuel so that it oscillates around a zero steering torque, thereby reducing or eliminating the locking conditions of the engine. torsion and allowing the operator to easily make the change manually to the neutral of the main section (see United States Patents 4,850,236 and 5,573,477). Screen 124 will steady illuminate the old gear ratio and will flash or otherwise indicate the selected ratio. The ECU 148 will detect the neutral conditions by comparing the ratio of the input shaft speed (IS) to the output shaft speed (OS) with known gear ratios. Alternatively or in combination, position sensors can be used. The logic will determine the identity of the GRT target change relation as a direct or indirect function of the current GRC change relation and the requested change direction. When neutral is detected in the main section, the screen element corresponding to the unlinked change relation will not illuminate, the splitter will automatically go to the appropriate splitter ratio and the motor will turn automatically (for a period of about 2-5). seconds) at a substantially synchronous speed (ES = OS * GRt) to link the target change ratio (GRT), allowing the operator to easily use the lever 31 manually to link the indicated main section ratio. Preferably, the motor will automatically rotate in an eccentric or will waver around the true synchronous speed (see U.S. Patent Nos. 5,508,916 and 5,582,558). Upon detecting the linkage of the target relationship, the indicator element of the screen corresponding to the newly linked relationship will light steady and the engine fuel control will be returned to the operator. The combined change with lever and splitter is achieved without requiring the operator to manipulate the clutch pedal 115 or the choke pedal 113. When in the shift position "A" 136 (ie, 9/10) or after the same, the ECU 146 will command the fuel controller 112 and the operator 116 of the splitter to automatically select and implement the appropriate changes 9-10 and 10-9. Automatic operation within a higher group of relationships is described in the aforementioned United States Patents Nos. 4,722,248; 4,850,236 and 5,498,195. Systems incorporating this feature are marketed by Eaton Corporation under the brand name "Super 10 Top-2" and by Dana Corporation under the brand name "Automate-2". To exit the "A" position, the operator can simply use the clutch pedal 115, the throttle pedal 113 and shift lever 57 to carry out a completely manual change to another relationship. If a change of the lever lever from "A" to the eighth (or a lower ratio) is required, the tilt element 120B of the selector can be retained in the AdownT position., which will cause the ECU 146 to command the fuel controller 112 and / or the splitter driver 116 to assist the lever or the combined lever-and-splitter ratio of the linked "A" relationship (ninth or tenth) to a selected objective relationship. The pulses of the selector (and the continuous movements "up"), when in the "A" position, are ignored by the ECU. In transmission systems such as the system 100, and in more automated systems, the system is provided with an indicator signal, or with a means for determining that a change in the main transmission section 16A is to be initiated. In accordance with the present invention, a detent mechanism is provided which provides variable resistance to the movement of the shift rail from a linked position. When the system detects a desire to remain in a linked relationship, the retainer provides a detent force that will provide excessively high resistance to the movement of the shift rail that will resist the jump induced by the shift lever. As a change is not taking place, this will not have an adverse effect on the quality of the change. When an intention to make a change of lever is detected or a change is in progress, it is not necessary to prevent the jump and the resistance or force is minimized to improve the quality of the change reducing the effort of change. In more automated systems, this will allow the use of smaller change actuators. Figure 5 illustrates an embodiment of a variable speed rail retainer mechanism. The shift rail 150 (also called "shift shaft") has notches in the gear 152 and 154 that will align with the detent mechanism 156 when the transmission is linked in, 5/6 or 9/10 ( A) or in R, H or 7/8, respectively. There is a surface 158 between the indentations 152 and 154. Alternatively, a small neutral retainer (illustrated in dotted lines) may be used. The shift rail 150 will typically carry one or more shift forks 151 to axially position the clutch members 151A in linked or unlinked positions, as is well known in the prior art. The detent mechanism includes a plunger 160 having a tapered tip 162 that is received in the notches and a piston end 164 received in a cylinder 166. A lightweight compression spring 168 pushes the plunger down to contact it with the notches. The piston and the cylinder define a selectively pressurized and emptied chamber 170 which is controlled by an actuator valve 172 under command from the ECU 146. Upon detecting the intent to effect a change, the chamber 170 is emptied to minimize resistance to movement. axial to the shift rail 150. Upon detecting the desire to remain engaged, the chamber 170 is pressurized to maximize the retaining force and, consequently, the resistance to axial movement of the shift rail to resist the jump induced by the shift lever . An on-board source S of pressurized fluid, such as hydraulic fluid or pressurized air, can be used to pressurize the chamber 170. The retainer mechanism of Figure 6 is similar to that illustrated in Figure 5 in that a shift rail is provided with notches 178 and 180 which correspond generally to notches 152 and 154, respectively. However, the notches 178 and 180 are not tapered. The notches 178 and 180 cooperate with a non-tapered tip 182 of a plunger element 184 of a detent mechanism 186. The plunger element 184 includes a two-sided piston portion. 188 received slidably and in seal relation in a cylinder 190. The piston portion 188 and the cylinder 190 define two separate chambers 192 and 194, which are alternately pressurized and emptied by the control valve 196 under command provided by the ECU 146 to make the plunger assume an extended or retracted position. The mechanism of Figure 6 provides positive resistance to axial movement in the shift rail 176, as opposed to the elastic resistance to axial movement of the shift rail 150 provided by the mechanism illustrated in Figure 5.

Both types of mechanisms, and modifications thereof, are appropriate for the present invention. Although the present invention has been described with a certain degree of particularity, it should be understood that the description of the preferred embodiment is by way of example only and that numerous changes in form and detail are possible without departing from the spirit and scope of the invention. according to the appended claims.

Claims (8)

1. CLAIMS 1. A transmission system comprising a shift element for moving a selected positive clutch to a selected one of a linked position and a disengaged position and a detent mechanism to provide a selectively variable resistance to the movement of said clutch element of a position linked to a disengaged position.
2. 2. A transmission system comprising a shift element for moving a selected positive clutch to a selected one of a linked or unlinked position and means for detecting the requirement to move said selected positive clutch from a position linked to a disengaged position and for providing a signal of intent to change indicative thereof, said system being characterized by: a detent mechanism for providing a resistance selectively variable to the movement of said clutch element from a position linked to a disengaged, said retainer mechanism having a first condition to provide greater resistance to the movement of said clutch from a position linked to a disengaged and a second condition to apply a lower resistance to the movement of said clutch from a position linked to a disengaged, said retaining mechanism assuming said second condition upon detecting said sign l of intent to change.
3. 3. A method for controlling a transmission system comprising a shift element for moving a selected positive clutch to a selected one of a linked or unlinked position, means for detecting the requirement to move said selected positive clutch from a position linked to a unlinked position and to provide a signal of intention to change indicative thereof, and a detent mechanism to provide a selectively variable resistance to the movement of said clutch member from a position linked to a disengaged, said detent mechanism having a first condition to provide greater resistance to the movement of said clutch from a position linked to a disengaged and a second condition to apply a lower resistance to the movement of said clutch from a position linked to a disengaged, said method comprising in the absence of said intention signal of change, make di The catch mechanism assumes said first condition, and upon detecting said signal of intention to change, cause said catch mechanism to assume said second condition.
4. A method according to claim 3, wherein said means provides a signal indicative of an objective change relation and said method further comprises causing said detent mechanism to assume said first condition upon detecting the binding of said objective change relation.
5. 5. A manually operated gear shift transmission system comprising a manually operated shift lever for moving a selected clutch element to a selected i of a linked or unlinked position, said transmission system comprising: means for detecting the desire of the operator to change said clutch member from a position linked to a disengaged and to provide a signal indicative thereof, and a detent mechanism to provide a selectively variable resistance to the movement of said clutch member from said position linked to said disengaged position , said detent mechanism having a first condition to provide greater resistance to the movement of said clutch from a position linked to a disengaged position and a second condition to apply a lower resistance to the movement of said clutch from a position linked to a disengaged, assuming saying locking mechanism said second position when detecting said signal.
6. 6. A partially automated transmission system comprising a fuel-controlled engine, a motor controller for controlling the fuel access of the motor according to the command output signals, a multiple speed mechanical transmission having an input shaft driven by the motor, an output shaft and a shifted transmission section by a manual shift lever, an operator selector that can be moved to a first position to select upshifts to an objective ratio and a second position to select downshifts to an objective ratio, and a control unit to receive input signals and processing them according to the predetermined logic rules for emitting command output signals, said system being characterized by: a detent mechanism for providing a selectively variable resistance to the movement of said shift lever from a position linked to a position disconnected from relationship, said catch mechanism having a first condition to provide greater resistance to the movement of said shift lever from a position linked in relation to a position disconnected from relation and a second condition to apply a lower resistance to the movement of said shift lever from a position linked in relation to a disconnected from relationship, and said logic rules being effective to determine an attempt by the driver to move said shift lever to a position disconnected from the relationship and, upon sensing said intent, cause said latching mechanism to assume said second condition.
7. A transmission system according to claim 6, wherein said shift lever is operable to cause axial movement of a shift rail, said detent mechanism comprising a notch in said rail and a thrust stop plunger with variable force to link with said notch.
8. 8. A transmission system according to claim 7, wherein said notch and said plunger are provided with complementary ramp surfaces.