Patent Description:
Detent pins have been conventionally used as part of the gearbox actuators. Some existing solutions related to the conventional detent pins can be found in the patent publications such as <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>.

<CIT> relates to a mechanical gearbox ball type locking device comprising three parallel fork spindles arranged in a triangle and individually movable between stable positions determined by ball notches. The ball cartridges engage the notches to ensure the locking of the fork spindles. There are only two ball cartridges arranged so as to ensure simultaneous balling of the three fork spindles and the relative locking of the spindles on the adjacent gear change lines.

<CIT> relates to a shifting device with detent and interlock unit, which comprises a first selector fork with a first locking unit and a second selector fork with a second locking unit. Both locking units are equipped with a spring supported locking element engaging with a complementary recess and causing the affected selector fork to move into a neutral position. A locking device is positioned between the locking element of the first unit and the locking element of the second unit keeping the first selector fork in the neutral position when the second fork is moved.

<CIT> relates to a restraining device between working shafts used for a transmission gear sliding mechanism of a transmission, a switching mechanism of a direction switching valve, and the like.

A pneumatically actuated gearbox for commercial vehicles may include one or more pneumatic actuators which are cylindrical in shape. Said pneumatic actuator includes a piston and a connecting rod attached to the piston.

As the piston linearly reciprocates within the pneumatic actuator, it results in the linearly reciprocating movement of the connecting rod. The connecting rod via downstream elements such as dog-clutch or synchronizers is connected to gear shafts where plurality of gears of the vehicle gearbox are provided. However, from the perspective of a gearbox and/or gearbox actuator manufacturer, it is imperative to prevent any accidental or unanticipated movement of the connecting rod of any single pneumatic actuator or relative movement between connecting rods (plural) associated with different pneumatic actuators within the gearbox actuator. As a consequence, no accidental engagement or disengagement of the gears occurs within the gearbox.

The present invention relates to one such fail-safe element provided within the gearbox actuators as there is a need for alternatives and/or further improvements to the existing solutions.

According to the present invention, the above mentioned problem is solved by a gearbox actuator according to claim <NUM>.

Preferred embodiments of the present invention are laid down in the dependent claims.

In accordance with an embodiment of the present invention a gearbox actuator comprising a dual-purpose detent pin is disclosed. Within the scope of the present invention, the term "dual-purpose detent pin" may be understood as follows.

Using detent pins to stop or inhibit or prohibit undesired movement of the respective shafts within the gearbox actuators are known (see the above background section). However, the dual-purpose detent pin of the present invention not only prevents the movement of an individual shaft of the gearbox actuator, but also prevents "relative" movement of a first shaft of the gearbox actuator with respect to the second shaft of the gearbox actuator. Further details and the detailed technical benefits of having such a dual-purpose detent pin, which is part of the gearbox actuator, as per the present invention will be explained in detail in association with detailed embodiments.

Accordingly, the dual-purpose detent pin, which is part of the gearbox actuator of the present invention, in accordance with an embodiment comprises two linearly reciprocating detent balls capable of linearly reciprocating along a vertical axis and are provided at opposite ends of the dual-purpose detent pin. In this regard, the "opposing ends" of the dual-purpose detent pin may refer to vertically opposite sides of a vertical axis (see e.g., reference sign "VA" in <FIG>, <FIG>, <FIG>) running through the dual-purpose detent pin.

The dual-purpose detent pin also includes a first and second holding structures for holding the two linearly reciprocating detent balls, respectively and are capable of linearly reciprocating along the vertical axis. According to the present invention, the first and second holding structures are capable of linearly reciprocating along the vertical axis in tandem with the two linearly reciprocating detent balls.

Furthermore, the dual-purpose detent pin of the present invention further comprises a spring being in contact with both the first and second holding structures, and is configured to allow a pre-determined range of linearly reciprocating opposing motion of at least one of the first and second holding structures and at least one of the two linearly reciprocating detent balls along the vertical axis.

The technical advantage of the dual-purpose detent pin according to the present embodiment as explained above and defined in claim <NUM> is that a single detent pin is used to prevent accidental (linear) movement of e.g., two shafts or gearshift rods provided in the gearbox actuator either separately or relative to each other.

In real-time application or use, as may also become apparent in the discussion of the further advantageous embodiments, the dual-purpose detent pin prevents accidental engagement of the incorrect gears (i.e., the gear not chosen or intended to be chosen by the vehicle operator) in a vehicle transmission caused due to the movement of the shafts associated with e.g., two pneumatic actuators in either of the directions of their movement. Such accidental movements of the shafts or rods associated with the pneumatic actuators of the gearbox may happen due faulty actuation of solenoid valves that control the flow of pressurized air into and out of the pneumatic actuators. Needless to say, as an element of fool-proof design of the gearbox actuators that such accidental movements of the shafts associated with the pneumatic actuators should be prevented. The dual-purpose detent pin of the present invention according to claim <NUM> enables such fool-proof design in accordance with an embodiment of the present invention.

In accordance with a preferred embodiment of the present invention, the first and second holding structures are separated by a predetermined gap, when the spring is in an extended state. In the present embodiment, the term "extended state" may be considered a state of the spring where it experiences relatively less compressive force. Furthermore, in the present illustrative embodiment, the predetermined gap may appear necessary in order to make the two linearly reciprocating detent balls of the dual-purpose detent pin be in contact with an external surface of each of the shafts (regardless of the profile of the external surface), whose accidental (linear) movement or whose relative movement with respect to each other should be prevented. Since this contact to the external surface of the each of the shafts should not be lost even when gear shifting i.e., the movement of the shafts do not occur, the predetermined gap helps maintaining contact with the external surface of the shafts with or without the tension in spring. The predetermining gap between the first and second holding structures is chosen taking the operating conditions of the dual-purpose detent pin into account.

In further preferred embodiments of the present invention, the dual-purpose detent pin further comprises an external sleeve to orient or align the two linearly reciprocating detent balls, the first and second holding structures, and the spring along the vertical axis. The sleeve that is discussed within the context of the present embodiment may simply be provided to keep the two linearly reciprocating detent balls and the first and second holding structures along the vertical axis.

In the same or different embodiments to the ones already discussed above, the dual-purpose detent pin is configured to prevent horizontal movement of at least one of two external shafts along their respective lateral axes depending on a relative axial position of one of the two external shafts along its lateral axis with respect to the axial position of the other of the two external shafts along its lateral axis. It is particularly advantageous that the dual-purpose detent pin in the present context can allow each of the two linearly reciprocating detent balls to selectively position itself in an appropriate provision provided in the two external shafts such that said horizontal movement of at least one of two external shafts along their respective lateral axes is prevented.

In conjunction with the dual-purpose detent pin of the previous embodiment discussed above, the relative axial position of one the two external shafts with respect to the other along its respective lateral axis or a relative difference in their respective axial positions along their respective lateral axes is correlated with the measure of physical distance between corresponding bottom surfaces of the two external shafts.

In the gearbox actuator according to the present invention, the each of the first and second external shafts comprises at least two crest-like and at least two trough-like sections on its outer surface. In accordance with the various embodiments of the present invention, the term "outer surface" should be read synonymously with the "external surface" in the context of the first and second external shafts. One of the technical purposes of having the crest-like and trough-like sections on the outer surface of the external shafts is to enable simplification of rolling of the two linearly reciprocating detent balls while at the same time the crest-like sections enable smoother application of compressive force on the spring of the dual-purpose detent pin.

According to an embodiment of the present invention, a first crest-like section of the each of the first and second external shafts is separated from a second crest-like section of the each of the first and second external shafts by a first trough-like section. This, as mentioned above, enables smoother transitory motion of the detent balls and furthermore is complementary to the profile or shape of each of the detent balls as it rolls or engages in transitory contact with the crest-and-trough-like sections along the external surface(s) of the first and second external shafts.

Furthermore, according to the present invention, a first diameter of the each of the first and second external shafts at the first crest-like section(s) is different from a second diameter at the second crest-like section(s) of the each of the first and second external shafts. The technical advantage of providing such different diameters at different sections of the first and second external shafts is to enable a locking feature in association with the dual-purpose detent pin of the present invention in that the predetermined gap or g<NUM> that exists between the first and second holding structures (at a certain state of operation of the gearbox actuator) may be reduced and/or increased if the diameters at the various sections of the first and second shafts are different. At a predefined situation, for instance, if the highest diameter at the crest-like section of the first external shaft coincides with the highest diameter at a crest-like section of the second external shaft (i.e., the relative position with respect to each other e.g., P3 in <FIG>), the detent balls that are in contact with the crest-like sections of the first and second external shafts cannot roll further in at least one direction because the gap between the first and second holding structures become "<NUM>" and the spring is fully compressed. More details on this would be explained further in association with the description provided for the accompanying drawings.

Moreover, a preferred embodiment provides for the option, in that radius of curvature r<NUM>, r<NUM>, or r<NUM> and/or a depth/ thickness t<NUM>, t<NUM>, t<NUM> and/or each of opposite inclined surfaces' <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> angle of inclination θ<NUM>, θ<NUM>, θ<NUM>, θ<NUM>, θ<NUM>, and θ<NUM> at each of the at least two trough-like sections <NUM>, <NUM> of the each of the first and second external shafts <NUM>, <NUM> is different from or same as the other. Such a variety of parameters to control the blocking of the relative movement between shafts <NUM> and <NUM> and/or individual linear movement of shafts <NUM> and <NUM> along their respective lateral axes LA1 and LA2 provides a gear actuator designer with a tremendous amount of options in arriving at an optimal solution. For instance, in combination with the varying diameters at the different sections of the external shafts, the changes with respect to the radius of curvature at the each of the at least two trough-like sections allow for specific design options (i.e., the freedom to design is improved) to provide the locking feature between the two external shafts of the gearbox actuator.

According to a preferred embodiment of the present invention, the two linearly reciprocating detent balls of the dual-purpose detent pin are configured to be in transitory contact with at least one of said crest-like sections and with at least one of said trough-like sections of the first and second external shafts, respectively, when the axial position of at least one of the first and second external shafts changes with respect to another of the first and second external shafts. Such a transitory contact between the two linearly reciprocating detent balls and the different curves of the external or outer surface of the shafts reduces the need of tending to lubrication needs between the contacting surface areas. Furthermore, in the same embodiment, the spring is compressed when at least one of the two linearly reciprocating detent balls is moving from one of the trough-like sections towards or is at one of the crest-like sections of the first second external shafts.

Further, the gearbox actuator according to one of the previously discussed embodiments, a gap (g<NUM>, g<NUM>, g<NUM>, g<NUM>) between the first and second holding structures of the dual-purpose detent pin vary depending on the relative positions of the first and second external shafts. One of the technical advantages, as will be understood within the scope of the present invention, is to provide this varying gap between the two holding structures such that the compression of the spring between the two holding structures are only allowed to an extent whereas the compression beyond that gap will either result in blocking of the relative movement between the two external shafts or in allowing the relative movement. Furthermore, the gearbox actuator of the previous embodiment, the gap (g3) between the first and second holding structures becomes "<NUM>" (no gap situation occurs), when a first of the two linearly reciprocating detent balls is initially engaged with a second trough-like section of the first external shaft, and when the linear translatory motion of the first external shaft in a first direction parallel to the respective lateral axis occurs such that the first of the two linearly reciprocating detent balls is made to roll towards a first crest-like section or a first crest-like section of the first external shaft. The technical purpose behind such a configuration is that, the designer is allowed to selectively prohibit the relative movement between the two external shafts only when said external shafts cause the change in the gears of the vehicle transmission and any reversal is prohibited. More precisely, the gap is made "<NUM>" between the holding structures by adjusting the profiles of curves along the external surface of the external shafts only when certain linear translator motion between the shafts are to be prevented.

In accordance with an exemplary embodiment of the present invention, a vehicle gearbox comprising the gearbox actuator as explained in any of above embodiments. In a yet another embodiment of the present invention, a commercial vehicle comprising the vehicle gearbox is claimed. In a still another embodiment, use of the claimed gearbox actuator is defined in claim <NUM>.

<FIG> illustrates a dual-purpose detent pin <NUM> and a part of a gearbox actuator <NUM> in accordance with an embodiment of the present invention.

Gearbox actuator <NUM> of an embodiment of the present invention includes a first external shaft <NUM>, a second external shaft <NUM> positioned parallel to first external shaft <NUM>, and a locking mechanism (not labeled in <FIG>) configured to prevent accidental horizontal movement of each of first and second external shafts <NUM>, <NUM> and/or any relative accidental horizontal movement between first and second external shafts <NUM>, <NUM> along their respective lateral axes LA1, LA2. The locking mechanism comprises dual-purpose detent pin <NUM>, which will be explained below in detail.

According to the present invention, said each of first and second external shafts <NUM>, <NUM> comprises at least two crest-like <NUM>, <NUM> and at least two trough-like sections <NUM>, <NUM> on its outer or external surface <NUM>. In accordance with one embodiment, which can also be common for all the embodiments of the present invention, external surface <NUM> and its shape at crest and trough-like sections as labeled as <NUM>, <NUM>, <NUM>, <NUM>, <NUM> of first external shaft <NUM> is same as that of external surface <NUM> of second external shaft <NUM>. It is for this reason, different reference signs is not used for each of these elements labeled on external shafts <NUM> and <NUM>. It may very well be understood that, in accordance with a preferred embodiment, external surface <NUM> of first external shaft <NUM> does not have to have same shape and features as that of the external surface of second external shaft <NUM>.

It is noted that it is the shape and features such as the crest and trough-like sections <NUM>, <NUM>, <NUM>, <NUM> and <NUM> on external surface <NUM> of first and second external shafts <NUM>, <NUM> equally along with dual-purpose detent pin <NUM> are configured to prevent accidental horizontal movement of each of first and second external shafts <NUM>, <NUM> and/or any relative accidental horizontal movement between first and second external shafts <NUM>, <NUM> along their respective lateral axes LA1, LA2.

As can also be derived from <FIG>, a first crest-like section <NUM> of the each of first and second external shafts <NUM>, <NUM> is separated from a second crest-like section <NUM> of the each of first and second external shafts <NUM>, <NUM> by a first trough-like section <NUM>. In the present embodiment, optionally, a first diameter α<NUM> of shaft <NUM> or α<NUM> of shaft <NUM> of the each of first and second external shafts <NUM>, <NUM> at first crest-like section(s) <NUM> is different from a second diameter α<NUM> at shaft <NUM> or α<NUM> of shaft <NUM> at second crest-like section(s) <NUM> of each of first and second external shafts <NUM>, <NUM>.

It is the difference in diameters at specific locations along shafts <NUM> and <NUM>, among other factors which will be discussed in conjunction with <FIG>, causes compression and elongation of spring <NUM>.

Dual-purpose detent pin <NUM> of the present embodiment, comprises two linearly reciprocating detent balls 108a and 108b capable of linearly reciprocating along a vertical axis VA and are provided at opposite ends of dual-purpose detent pin <NUM>. Dual-purpose detent pin <NUM> also includes a first and second holding structures 110a 110b or holding the two linearly reciprocating detent balls 108a and 108b, respectively and are capable of linearly reciprocating along the vertical axis VA. In an embodiment, first and second holding structures <NUM> and are capable of linearly reciprocating along the vertical axis VA in tandem with two linearly reciprocating detent balls 108a and 108b.

Furthermore, dual-purpose detent pin <NUM> of the present embodiment further comprises a spring <NUM> being in contact with both first and second holding structures 110a and 110b, and is configured to allow a pre-determined range of linearly reciprocating opposing motion of at least one of first and second holding structures 110a 110b and at least one of the two linearly reciprocating detent balls 108a and 108b along vertical axis VA. In accordance with an embodiment, instead of a single spring, two springs may be provided between first and second holding structures 110a and 110b. In a special implementation, a double helical compression spring or a coil spring may be used between first and second holding structures 110a and 110b.

The technical advantage of dual-purpose detent pin <NUM> according to the present embodiment as explained above is that a single detent pin is used to prevent accidental (linear) movement of e.g., two shafts (108a and 108b) or gearshift rods (108a and 108b) provided in gearbox actuator <NUM> either separately or relative to each other.

In real-time application or use, as may also become apparent in the discussion of the further advantageous embodiments, dual-purpose detent pin <NUM> prevents accidental engagement of the incorrect gears (i.e., the gear not chosen by the vehicle operator) in a vehicle transmission caused due to the movement of the shafts (e.g., likes the ones shown in <FIG> with reference signs <NUM> and <NUM>) associated with e.g., two separate pneumatic actuators in either of the directions (such as the ones parallel to the lateral axis LA1 or LA2) of their movement. Such accidental movements of the shafts or rods associated with the pneumatic actuators of the gearbox may happen due faulty actuation of solenoid valves (not shown in any of the accompanying figures) that control the flow of pressurized air into and out of the pneumatic actuators (not shown in any of the accompanying figures). Needless to say, as an element of fool-proof design of the gearbox actuators (at least part of which is shown in <FIG> with reference sign "<NUM>") that such accidental movements of the shafts associated with the pneumatic actuators should be prevented. Dual-purpose detent pin <NUM> of the present invention according to claim <NUM> enables such fool-proof design in accordance with the present embodiment of the invention.

In accordance with one or more embodiments of the present application, spring <NUM> can be a constant rate spring (where the stiffness is constant along the length of the spring) or a variable rate spring (where the stiffness varies along the length of the spring). For instance, the springs with variable rate may provide the technical advantage of providing more or less compression at one end (e.g., one vertical end along axis 'VA' in <FIG>) of dual-purpose detent pin <NUM> in comparison to another end of (e.g., other vertical end along axis 'VA' in <FIG>).

It may be understood that only part of gearbox actuator <NUM> is shown in <FIG>. For instance, just for the clarity, it is reiterated that the shafts <NUM> and <NUM> are the ones that extend from the pneumatic actuators that are for gear-shifting and gear-selection purposes. For instance, each of said pneumatic actuators can be two or three-position cylinders, depending the type of vehicle and/or vehicle gearbox that they are associated with. What may however be clear is, when one of the gears of the vehicle gearbox is engaged with and the driver or vehicle operator does not intend on changing this, there should be no "accidental" actuation occurring.

Furthermore, in accordance with the present embodiment, first and second holding structures 110a, 110b are separated by a predetermined gap (g<NUM>), when spring <NUM> is in an extended state. For instance, for the sake of illustration, it is noted spring <NUM> enables that the predetermined gap in accordance the present embodiment to be g<NUM> because first and second linearly reciprocating detent balls 108a and 108b are positioned at a first and a second trough-like section <NUM> and <NUM> on at least external surface <NUM> of first external shaft <NUM>. Due to the dip at first and second trough-like sections <NUM> and <NUM>, it is to be understood that spring <NUM> is at an extended state.

In the same embodiment, dual-purpose detent pin <NUM> further comprises an external sleeve <NUM> to orient or align the two linearly reciprocating detent balls 108a, 108b, first and second holding structures 110a, 110b, and spring <NUM> along the vertical axis (VA). For instance, external sleeve <NUM> that is discussed within the context of the present embodiment may simply be provided to keep two linearly reciprocating detent balls 108a and 108b and the first and second holding structures 110a and 110b along the vertical axis.

During the use of dual-purpose detent pin <NUM> of the present embodiment, dual-purpose detent pin <NUM> is configured to prevent horizontal movement of at least one of two external shafts <NUM>, <NUM> along their respective lateral axes LA1, LA2 depending on a relative axial position of one of the two external shafts <NUM>, <NUM> along its lateral axis LA1 with respect to the axial position of the other of the two external shafts <NUM>, <NUM> along its lateral axis LA2. For instance, see <FIG>, which is under discussion for explaining this current embodiment, in which a first bottom surface 102b of first external shaft <NUM> is directly in alignment with a second bottom surface 104b of second external shaft <NUM>. This denotes that the relative axial positions of first external shaft <NUM> and second external shaft <NUM> are aligned with each other. This relative axial position is displayed in <FIG> with the help of reference P<NUM>. Incidentally, first linearly reciprocating detent ball 108a as shown in <FIG> is positioned at a second trough-like section <NUM> of first external shaft <NUM> and second linearly reciprocating detent ball 108b is positioned at second trough-like section <NUM> of second external shaft <NUM>.

In accordance with the present embodiment, the relative axial position of one of the two external shafts i.e., first external shaft <NUM> with respect to the other i.e., second external shaft <NUM> along its respective lateral axis LA1 or LA2 or a relative difference in their respective axial positions along their respective lateral axes LA1, LA2 is correlated with the measure of physical distance between corresponding bottom surfaces 102b, 104b of the two external shafts <NUM>, <NUM>.

In real-time gearbox application, the relative position P<NUM> as indicated in <FIG> and the position of first and second linearly reciprocating detent balls 108a and 108b at second tough-like section(s) <NUM> of first and second external shafts may indicate a "neutral" gear position. Thus, when the vehicle transmission or the gearbox is engaged in the neutral gear at which state the engine transmission output is not transferred to a driven shaft within the gearbox, the relative position of first and second external shafts <NUM> and <NUM> of the pneumatic actuators (not shown) referred as P<NUM> is observed.

Further positions that are possible and the relative positions P1, P2 and P3 are explained within the contexts of <FIG>, <FIG>.

Still furthermore, two linearly reciprocating detent balls 108a, 108b of dual-purpose detent pin <NUM> are configured to be in transitory contact with at least one of said crest-like sections <NUM>, <NUM> and with at least one of trough-like sections <NUM>, <NUM> of first and second external shafts <NUM>, <NUM>, respectively, when the axial position of at least one of first and second external shafts <NUM>, <NUM> changes with respect to another of first and second external shafts <NUM>, <NUM>, and wherein spring <NUM> is compressed when at least one of two linearly reciprocating detent balls 108a, 108b is moving from one of trough-like sections towards or is at one of crest-like sections <NUM>, <NUM> of first second external shafts <NUM>, <NUM>. The technical purpose of enabling this transitory contact with crest-like and trough-like sections of first and second external shafts <NUM>, <NUM> will become apparent with the explanation provided in conjunction with <FIG>, <FIG>.

In the same embodiment, a gap g<NUM> (c. <FIG>) between first and second holding structures 110a and 110b of dual-purpose detent pin <NUM> is shown, which gap g<NUM> depending on the relative positions of first and second external shafts <NUM> and <NUM>. One of the technical advantages, as will be understood within the scope of the present invention, is to provide this varying gap between two holding structures <NUM> and <NUM> such that the compression of spring <NUM> between two holding structures <NUM> and <NUM> are only allowed to an extent whereas the compression (of spring <NUM>) beyond a certain threshold of gap will either result in blocking of the relative movement between two external shafts <NUM> and <NUM> or in allowing said relative movement.

Working principle of the present invention will be explained herewith to the extent that it can be done with the help of assistance to what is disclosed in <FIG>. However, it be noted that this working principle will become further clearer when the explanation for <FIG>, <FIG>, <FIG> are provided.

As can be taken from <FIG>, first and second external shafts <NUM> and <NUM> are positioned parallel to each other as shown representatively with the help of lateral axes LA1 and LA2. Each of first and second external shafts <NUM> and <NUM> are connected to two pneumatic actuators (not shown in the accompanying Figures). Each of the two pneumatic actuators can serve individual purposes. For instance, one of the two pneumatic actuators can be a first "shift" actuator (e.g., responsible for gear shift; not shown in the figures) that is dedicated for shifting between second and third gears whereas the other of the two pneumatic actuators can be a second "shift" actuator (not shown in the figures) that is responsible for shifting between first and reverse gears.

Thus, by using dual-purpose detent pin <NUM> according to the present invention, a mechanical interlock system (or simply a locking system) is implemented between the first shift actuator that is responsible for first and reverse gears and the second shift actuator that is responsible for shifting between the second and third gears. This mechanical interlock system (or the locking system) allows some movement of the opposite gear of the one engaged, but during an engaging action of the second or third gears, any movement on the shaft from the actuator responsible for engaging the first and reverse gears is blocked.

It may be understood that one of the technical advantages of dual-purpose detent pin <NUM> according to the present invention is that it not only prevents the linear movement which are undesired in one shaft, but also the undesired relative linear movement between two shafts. By this way, the accidental or undesired engagement or change of the gears is prevented in a fool proof manner.

Furthermore, in order to achieve the above-mentioned effect or technical advantage following list of non-exclusive parameters, among others, may be carefully considered:.

Further details of the parameters associated with enabling the locking mechanism as discussed above, will also become apparent in the discussion in relation to <FIG>.

Generally, when a gear shift is requested by an operator of the vehicle, one of first and second external shafts <NUM> and <NUM> are moved along their respective lateral axes LA1 and LA2, respectively. In accordance with the present embodiment, the engaged gear is neutral and the relative positions of shafts <NUM> and <NUM> reflect that in that bottom surfaces 102b and 104b of first and second shafts <NUM> and <NUM> are aligned with respect to each other as indicated at P0 in <FIG>. At this relative position of neutral, first and second linearly reciprocating detent balls 108a and 108b are positioned at trough-like section <NUM> (see <FIG>). Thus, when a gear change occurs, one or both detent balls 108a and 108b roll(s) along an external surface <NUM> and compress spring <NUM> as they move towards at least one of crest-like sections <NUM>, <NUM>. However, the compression of spring <NUM> has a limit in that it occurs in so far as the gap (see e.g., g0) exists between first and second holding structures 110a and 110b. This gap between first and second holding structures 110a and 110b is carefully designed such that not relative movements between first and second external shafts <NUM> and <NUM> (see, e.g., <FIG>).

<FIG> illustrates a section of second external shaft <NUM> of gearbox actuator <NUM> in accordance with an embodiment of the present invention.

In particular, section "1b" from <FIG> is shown in an enlarged manner in <FIG>. As can be noticed, trough-like sections <NUM>, <NUM>, <NUM> as well as crest-like sections <NUM>, <NUM> are shown in a closer view. It should be noted that this is only an exemplary illustration.

In accordance with the embodiment disclosed in <FIG>, only section 1b of <FIG> at second external shaft <NUM> is displayed. However, it must be understood similar parameters will come into picture also within the design of the corresponding section at first external shaft <NUM>. In other words, the parameters discussed herein is not only applicable to second external shaft <NUM>, but may also be applicable to first external shaft <NUM> within the scope of the present application.

As can be noticed from <FIG>, each trough-like section <NUM>, <NUM> and <NUM> are shown to have unique radius r<NUM>, r<NUM> and r<NUM>, but at least two trough-like sections <NUM>, <NUM> and <NUM> can have different radii in comparison to each other. The radius of each of trough-like sections <NUM>, <NUM> and <NUM> contribute to either directly or indirectly and at least to an extent whether a linear movement of one of shafts <NUM>, <NUM> or its relative movement with the other is allowed or should be locked.

In <FIG>, furthermore, angles of inclinations θ<NUM>, θ<NUM>, θ<NUM>, θ<NUM>, θ<NUM>, and θ<NUM> of opposite inclined surfaces <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> associated with each of trough-like sections <NUM>, <NUM> and <NUM>, respectively. Said of angles of inclinations θ<NUM>, θ<NUM>, θ<NUM>, θ<NUM>, θ<NUM>, and θ<NUM> are illustrated taking a horizontal surface or external surface <NUM> of second shaft <NUM> as a reference horizontal line/plane. As would one decipher from <FIG>, said angles of inclinations of each of the opposing surfaces of trough-like sections <NUM>, <NUM> and <NUM> has a direct effect on what e.g., depths or thicknesses (t<NUM>, t<NUM>, tz) at trough-like sections <NUM>, <NUM>, <NUM> with reference to surface <NUM>. By controlling each of these parameters or one or more of these parameters including the angles of inclinations of the opposite inclined surfaces, radii of curvature, and the thicknesses, the present invention, in an exemplary illustration, provides a precise control or fool proof provision of preventing whether one or more of detent balls 108a and 108b rolls over from one trough-like section <NUM> (as shown in <FIG>) to another trough-like section (see <FIG> and <FIG>) or not (see <FIG>).

Moreover, the present embodiment provides for the option, in that radius of curvature r<NUM>, r<NUM>, or r<NUM> and/or a depth/ thickness to, t<NUM>, t<NUM> and/or each of opposite inclined surfaces' <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> angle of inclination θ<NUM>, θ<NUM>, θ<NUM>, θ<NUM>, θ<NUM>, and θ<NUM> at each of the at least two trough-like sections <NUM>, <NUM> of the each of the first and second external shafts <NUM>, <NUM> is different from or same as the other. Such a variety of parameters to control the blocking of the relative movement between shafts <NUM> and <NUM> and/or individual linear movement of shafts <NUM> and <NUM> along their respective lateral axes LA1 and LA2 provides a gear actuator designer with a tremendous amount of options in arriving at an optimal solution.

<FIG> illustrates of working of a dual-purpose detent pin within gearbox actuator <NUM> in accordance with one or more embodiments of the present invention.

<FIG>, in accordance with an embodiment, shows a transitory movement of second external shaft <NUM> as shown with the help of arrow mark "M" whereas first external shaft <NUM> is stationary or immobile at that point. Due to its movement along direction "M" along lateral axis LA2, second external shaft <NUM> compresses spring <NUM> due to the linearly reciprocating movement of second linearly reciprocating detent ball 108b along a vertical axis VA in an upper direction. To illustrate the movement of second linearly reciprocating detent ball 108b along vertical axis VA, the upper direction is marked in <FIG> with the arrow mark "U" so that its clear on what is actually mean by the "upper direction". In accordance with the present invention, the upper direction "U" can be understood to be as a direction that indicates starting from second external shaft <NUM> and pointing towards first external shaft <NUM>, and at the same time is perpendicular to lateral axis LA2 or LA1. Thus, second linearly reciprocating detent ball <NUM> is shown "half-way" through the movement of second external shaft <NUM> when a gear shift is occurring.

It should be noted that, at this stage, gap "g<NUM>" between first and second holding structures 110a and 110b is reduced or lesser in magnitude (millimeters 'mm') in comparison to gap "g<NUM>" of <FIG>, but is not entirely "zero" or <NUM>. Such a state would indeed allow further movement of second external shaft <NUM> along axis LA2 in the direction "M". The resulting position is shown or indicated in <FIG> where second linearly reciprocating detent ball 108b is positioned at first trough-like section <NUM> of second external shaft <NUM>. As is also noticeable the relative horizontal position P1 between first and second external shafts <NUM> and <NUM> of <FIG> has changed in <FIG> with the newer relative horizontal position P2. In other words, the distance between bottom faces 102b and 104b of first and second external shafts <NUM> and <NUM> has increased due to horizontal movement of second external shaft <NUM> purely by comparing the relative positions of said shafts in <FIG> and <FIG>.

For instance, in accordance with an embodiment, the relative movement of shafts <NUM> and <NUM> can result in shifting gears from a second to third gear in the gearbox (not shown in the figures). However, it should be noticed that, during such a shift of gear, the movement of first external shaft <NUM> along direction "M" of as shown in <FIG> should be stopped.

This is achieved as shown in <FIG> where first external shaft <NUM>'s movement "M" along lateral axis LA1 is prevented because when the transitionary movement of first linearly reciprocating ball 108a occurs, while moving from second trough-like section <NUM> to first trough-like section <NUM>, the gap g<NUM> has already become "<NUM>" (see <FIG>). The rolling point where the transitory contact of first linearly reciprocating ball 108a is stopped is indicated with a reference sign <NUM> in <FIG>.

Alternatively explained, in the present embodiment, the gap (g3) between the first and second holding structures 110a, 110b becomes "<NUM>" or no gap situation occurs, when first of two linearly reciprocating detent balls i.e., 108a of balls 108a, 108b is initially engaged with second trough-like section <NUM> of first external shaft <NUM>, and when the linear translatory motion of first external shaft <NUM> in a first direction M parallel to the respective lateral axis LA1 occurs such that first of the two linearly reciprocating detent balls i.e., 108a is made to roll towards first crest-like section <NUM> or a first trough-like section <NUM> of first external shaft <NUM>.

Due the above-mentioned scheme of operation or sequence of operations, dual purpose detent pin <NUM> of the present inventing, being part of gearbox actuator <NUM> or its locking mechanism, prevents accidental horizontal movement of each of first and second external shafts <NUM>, <NUM> and/or any relative accidental horizontal movement between first and second external shafts <NUM>, <NUM> along their respective lateral axes LA1, LA2.

Claim 1:
A gearbox actuator (<NUM>), comprising
a first external shaft (<NUM>),
a second external shaft (<NUM>) positioned parallel to the first external shaft (<NUM>), and
a locking mechanism configured to prevent accidental horizontal movement of each of the first and second external shafts (<NUM>, <NUM>) and/or any relative accidental horizontal movement between the first and second external shafts (<NUM>, <NUM>) along their respective lateral axes (LA1, LA2),
wherein the locking mechanism comprises a dual-purpose detent pin (<NUM>), comprising
two linearly reciprocating detent balls (108a, 108b) capable of linearly reciprocating along a vertical axis (VA), and being provided at opposite ends of the dual-purpose detent pin (<NUM>),
a first and second holding structures (110a, 110b) for holding the two linearly reciprocating detent balls (108a, 108b), respectively and are capable of linearly reciprocating along the vertical axis (VA), and
wherein the dual-purpose detent pin (<NUM>) further comprises
a spring (<NUM>) being in contact with both the first and second holding structures (110a, 110b), and is configured to allow a pre-determined range of linearly reciprocating opposing motion of at least one of the first and second holding structures (110a, 110b) and at least one of the two linearly reciprocating detent balls (108a, 108b) along the vertical axis (VA), wherein the each of the first and second external shafts (<NUM>, <NUM>) comprises at least two crest-like (<NUM>, <NUM>) and at least two trough-like (<NUM>, <NUM>) sections on its outer surface (<NUM>) wherein a first crest-like section (<NUM>) of the each of the first and second external shafts (<NUM>, <NUM>) is separated from a second crest-like section (<NUM>) of the each of the first and second external shafts (<NUM>, <NUM>) by a first trough-like section (<NUM>), and
characterized in that, a first diameter (α<NUM> or α<NUM>) of the each of the first and second external shafts (<NUM>, <NUM>) at the first crest-like section(s) (<NUM>) is different from a second diameter (α<NUM> or α<NUM>) at the second crest-like section(s) (<NUM>) of the each of the first and second external shafts (<NUM>, <NUM>).