Clutch and gear synchronizer module

A clutch and gear synchronizer module includes an actuator disposed radially with respect to the transmission shaft and carried by an actuator carrier connected to the transmission shaft for rotation with the transmission shaft. The actuator includes an offset pin coupled to a shift sleeve that is able to move axially with respect to the transmission shaft thereby causing axial and rotational movement of the offset pin and rotation of the actuator about an actuator axis. The actuator includes a lobe and a pawl. Sequentially, the lobe engages a friction ring thereby causing the friction ring to engage the gear and causing the gear to rotate in synchronization with the transmission shaft. As the shift sleeve moves further towards the gear, the pawl then engages clutch teeth disposed on an annular surface of the gear.

BACKGROUND

Technical Field

This disclosure relates to clutches or clutch modules for manual transmissions of automobiles that facilitate synchronization of the rotational speed of the selected gear with the rotational speed of the transmission shaft.

Description of the Related Art

An internal combustion engine of an automobile generates power in the form of reciprocating motion of its pistons. The crankshaft converts this reciprocal motion into rotary motion. The rotary motion of the crankshaft, however, is not transmitted directly to the driving wheels or to the drivetrain because the crankshaft rotates at high rotational speeds, which are inappropriate for starting, stopping and normal travel. Specifically, automobile engines typically operate over a range of about 600 to about 7000 rpm, while the wheels rotate between 0 rpm and about 1800 rpm. It is the function of the transmission to convert the high rotational speed of the crankshaft to a slower wheel speed and to increase torque in the process. While both manual and automatic transmissions provide the same basic functions of speed reduction and torque increase, this disclosure relates to manual transmissions.

Instead of connecting directly to the transmission, the crankshaft connects to a flywheel, which connects to a transmission input shaft, sometimes referred to as a mainshaft. In one example, the transmission selectively couples the input shaft through two gear sets, each providing a gear ratio, and eventually to an output shaft, sometimes referred to as the driveshaft. In many designs, the input shaft fixedly connects to an input pinion that meshes with an input gear fixedly connected to a parallel counter shaft. Thus, the counter shaft rotates with the input shaft, but at a somewhat lower speed to the gear ratio provided by the input pinion and the input gear of the counter shaft. The counter shaft also fixedly connects to a plurality of gears, typically numbered from one to four, five or six. Each of these numbered gears, which rotate with the counter shaft, also mesh with and form gear sets with like-numbered gears through which an output shaft passes. The numbered gears of the output shaft do not connect to the output shaft, but instead ride on bearings. Each pair of enmeshed numbered gears, one on the counter shaft and one on the output shaft, form a gear set and provide a gear ratio. Because the output shaft is not fixedly connected to the numbered gears through which it passes, the transmission also includes a plurality of clutches or clutch modules that selectively couple the output shaft to one of these numbered gears and therefore to one of the gear sets.

Manual transmissions are available in a variety of different designs and clutch modules may be required to connect gear sets to an input shaft, one or more counter shafts or an output shaft. Hence, use of the term “transmission shaft” below may refer to any shaft of a transmission that may be selectively coupled to a gear set by a clutch module.

Before a transmission shaft connects to one of the gears through which it passes, or before a gear shift takes place, it is preferable to have the selected gear rotating at or about the same speed as the transmission shaft to which it will be coupled. This process is known as synchronization. Modern manual transmissions include various means for achieving synchronization of the transmission shaft with the selected gear, or the gear set being shifted to, so the transmission shaft and the selected gear rotate at about the same rotational velocity when the shift takes place. Synchronization may be achieved with synchronizing rings, as disclosed initially in U.S. Pat. No. 2,579,090 and later in U.S. Pat. No. 3,688,883. As shown in U.S. Pat. No. 3,688,883, a synchronization ring may couple to the selected gear or to a clutch body mounted to the selected gear. As gear shifting commences, a shift sleeve, which rotates with the transmission shaft, moves into frictional engagement with the synchronization ring before clutch teeth of the shift sleeve engage clutch teeth of the selected gear. The frictional engagement between the shift sleeve and the synchronization ring imparts rotation to the selected gear. As a result, the transmission shaft (and shift sleeve) and the selected gear rotate at or about the same rotational speed before the shift to the selected gear, or the selected gear set, is completed. Synchronizing rings typically include a conical friction surface, which engages a corresponding conical surface on the selected gear (or clutch body connected to the selected gear). The resulting frictional engagement between the synchronizing ring and the selected gear establishes the desired synchronization between the transmission shaft and the selected gear.

Clutch modules that perform synchronization as well as gear shifting can be complex in design, difficult to assemble and therefore costly to produce. Further, as noted above, multiple clutch modules may be required. Accordingly, a need exists for improved clutch and synchronization modules that are easy to assemble, reliable and cost efficient to produce.

SUMMARY OF THE DISCLOSURE

In one aspect, this document discloses a clutch and gear synchronizer module for transmission that includes a transmission shaft that passes coaxially through a first gear assembly. The transmission shaft may be an input shaft, an output shaft or a counter shaft. The first gear assembly may include or be coupled to a structure that provides a frictional surface and a recess. The transmission shaft is rotatable about a transmission axis. The clutch and gear synchronizer module may include an actuator carrier mounted on the transmission shaft for rotation with the transmission shaft about the transmission axis. The actuator carrier may be disposed radially within and coupled to a shift sleeve for imparting rotation to the shift sleeve while enabling the shift sleeve to move axially with respect to the actuator carrier. The actuator carrier may include an inner hub connected to an outer ring with a window disposed between the inner hub and the outer ring. The clutch and gear synchronizer module may further include a first friction element disposed between the first gear assembly and the actuator carrier. The first friction element may be coupled to the actuator carrier for rotation with the actuator carrier while enabling the first friction element to move axially with respect to the actuator carrier. The clutch and gear synchronizer module may further include an actuator that extends radially between the inner hub and the outer ring and across the window of the actuator carrier. The actuator may be rotatable about an actuator axis that extends radially between the inner hub and the outer ring. The actuator may include a lobe and a pawl disposed in radial alignment with the window. The lobe may also be in radial alignment with the first friction element while the pawl may also be in radial alignment with the frictional surface of the first gear assembly. The actuator may further include an outwardly directed offset pin that is parallel to, but not coaxial with the actuator axis. The offset pin may couple to the shift sleeve.

In another aspect, this document discloses a clutch and gear synchronizer module for a transmission that includes a transmission shaft that passes coaxially through a first gear assembly and a second gear with the clutch and gear synchronizer module disposed between the first and second gears. The first gear assembly may include or be coupled to a structure that provides a circular pattern of clutch teeth and a circular recess that face the clutch and synchronizer module. The second gear may also include a circular pattern of clutch teeth and a circular recess that face the clutch and synchronizer module. The transmission shaft may be rotatable about a transmission axis. The clutch and gear synchronizer module may include an actuator carrier mounted on the transmission shaft for rotation with the transmission shaft. The actuator carrier may be disposed radially within and coupled to a shift sleeve for imparting rotation to the shift sleeve. The clutch and synchronizer module may also include a first friction ring coupled to the actuator carrier and at least partially disposed within the circular recess of the first gear assembly and a second friction ring coupled to the actuator carrier and at least partially disposed within the circular recess of the second gear. The actuator carrier may include an inner hub connected to an outer ring by a pair of struts with a window disposed between the inner hub and the outer ring and between the struts. The clutch and synchronizer module may further include a pair of actuators. Each actuator may include a shaft or main body having an inner end rotatably connected to the inner hub of the actuator carrier and an outer end rotatably connected to the outer ring of the actuator carrier. Each shaft of each actuator may connect to a lobe and a pawl that are disposed in radial alignment with a window. Each lobe may also be in radial alignment with the first and second friction rings. Each pawl may also be in radial alignment with the circular patterns of clutch teeth of the first and second gears. The shafts of the actuators may each be connected to an outwardly directed offset pin that is parallel to, but not coaxial with, its respective shaft. The offset pins may couple to the shift sleeve. An initial movement of the shift sleeve and offset pins towards the first gear assembly causes the lobes to rotate into engagement with the first friction ring and push the first friction ring farther into the circular recess of the first gear assembly, thereby causing the first gear assembly to rotate with the clutch and synchronizer module. Further axial movement of the shift sleeve toward the first gear assembly causes at least one of the pawls to engage the circular pattern of clutch teeth of the first gear assembly. Further, an initial movement of the shift sleeve and offset pins towards the second gear causes the lobes to rotate into engagement with the second friction ring and push the second friction ring into the circular recess of the second gear thereby causing the second gear to rotate with the clutch synchronizer module. In addition, further axial movement of the shift sleeve towards the second gear causes at least one of the pawls to engage the circular pattern of clutch teeth of the second gear.

In another aspect, this document discloses a method for synchronizing a rotational speed of a gear with a rotational speed of a transmission shaft and for transferring torque from the transmission shaft to the gear. The method may include providing a gear that includes or is coupled to a structure that provides an annular surface that includes a circular pattern of clutch teeth and a circular recess. The method may further include providing a clutch and synchronizer module including an actuator carrier disposed radially within and coupled to a shift sleeve. The clutch and synchronizer module may also include a friction ring coupled to the actuator carrier. The actuator carrier may include an inner hub connected to an outer ring with a window disposed between the inner hub and the outer ring. The clutch and synchronizer module may further include an actuator that includes and actuator shaft or main body that extends radially between the inner hub and the outer ring and across the window of the actuator carrier. The actuator shaft may be connected to a lobe and a pawl that are disposed in radial alignment with the window and with the lobe also in radial alignment with the friction ring and the pawl also in radial alignment with the circular pattern of clutch teeth of the gear. The actuator shaft may connect to an outwardly directed offset pin that is parallel to but not coaxial with the actuator shaft. The offset pin may couple to the shift sleeve. The method may further include mounting the clutch and synchronizer module on the transmission shaft for rotation with the transmission shaft. The method may further include passing a transmission shaft through the gear so the gear is disposed adjacent to the clutch and synchronizer module. The method may further include moving the shift sleeve and offset pin towards the gear an initial distance thereby causing the lobe to rotate into engagement with the friction ring and push the friction ring into the circular recess of the gear thereby causing the gear to rotate with the clutch and synchronizer module and the transmission shaft. In addition, the method may include moving the shift sleeve and offset pin further towards the gear to cause the pawl to rotate into engagement with the circular pattern of clutch teeth of the gear.

Other advantages and features will be apparent from the following detailed description when read in conjunction with the attached drawings.

The drawings are not necessarily to scale and may illustrate the disclosed embodiments diagrammatically and in partial views. In certain instances, the drawings omit details which are not necessary for an understanding of the disclosed methods and apparatuses or which render other details difficult to perceive. Further, this disclosure is not limited to the particular embodiments illustrated herein.

DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIGS. 1-6illustrate a disclosed clutch and gear synchronizer module20mounted on a transmission shaft21for rotation with the transmission shaft21. The transmission shaft21may be an input shaft, a counter shaft or an output shaft, as will be apparent to those skilled in the art. Typically, the clutch and gear synchronizer module20is installed on an input shaft or an output shaft, but those skilled in the art will realize that the clutch and gear synchronizer module20may also be installed on a counter shaft in some transmissions. Thus, the transmission shaft21may be any one of the shafts of a manual transmission.

FIGS. 1-4sequentially illustrate the module20as the module20shifts from a neutral position (FIG. 1) to a position where the selected gear22synchronizes with the transmission shaft21(FIG. 2) to a position just before the pawls23engage the clutch teeth24of the selected gear22(FIG. 3) to the fully engaged position where the pawls23fully engage the clutch teeth24of the selected gear22(FIG. 4).

Returning toFIG. 1, the transmission shaft21may pass through a plurality of gears, including the gear25shown at the left inFIGS. 1-4and the selected gear22shown at the right inFIGS. 1-4. The transmission shaft21may couple to the module20via a splined connection (not shown) between the middle section26of the transmission shaft21and the inner hub27of the actuator carrier28, which is better illustrated inFIGS. 5-7. Still referring toFIG. 1, the transmission shaft21passes through the gears25,22with needle bearings (not shown) disposed between the inner surfaces31,32of the gears25,22and the transmission shaft21. The transmission shaft21may optionally include a flange33disposed on one side of the gears25,22and the module20with a retainer34disposed on the opposite side of the gears25,22and the module20. The actuator carrier28of the module20is disposed radially within a shift sleeve35, which couples to the actuator carrier28for rotation with the actuator carrier28and the transmission shaft21. However, the shift sleeve35may slide axially to the right or to the left as will be explained below. In contrast, the actuator carrier28is maintained in its axial position between the gears25,22by the step36, retainer34and washer37. The shift sleeve35may include a recess38at its outer periphery for receiving a shift fork (not shown) or other device for moving the shift sleeve35to the right or to the left, or, more specifically, towards the gear22or towards the gear25. The module20also includes a friction ring41partially received in the recess42of the gear22when the module20is in the neutral position as shown inFIG. 1. Further, the module20also includes a friction ring43partially received within the recess44of the gear25when the module20is in the neutral position as shown inFIG. 1.FIGS. 5-9further illustrate various details of the module20.

Turning toFIGS. 5-6, the splined connection couples the inner hub27of the actuator carrier28to the transmission shaft21for rotation with the transmission shaft21. Other means for connecting the actuator carrier28to the transmission shaft21for rotation with the transmission shaft21will be apparent to those skilled in the art. The inner hub27of the actuator carrier28connects to an outer ring45via one or more struts46. The actuator carrier28includes one or more windows47disposed between the inner hub27and the outer ring45and between pairs of struts46as shown inFIGS. 5-6. One or more actuators48extend radially across each window47and radially between the inner hub27and the outer ring45.

Turning toFIGS. 8-9, an actuator48may include or be connected to a pawl23as well as a lobe51, both of which extend radially outwardly from an actuator axis52. In the embodiment shown inFIGS. 8-9, the actuator48may include an actuator shaft53(or main body) that may include an inner end54and an outer end55. As shown inFIGS. 5-6, the inner hub27of the actuator carrier28includes inner recesses56that rotatably receive the inner ends54of the actuators48. Similarly, the outer ring45of the actuator carrier28includes a plurality of through holes57that rotatably receive the outer ends55of the actuators48. Thus, as shown inFIGS. 5-6the actuators48extend radially between the inner hub27and outer ring45of the actuator carrier28. Further, the actuators48may rotate about their actuator axes52, which are perpendicular to the transmission shaft axis58(see alsoFIG. 1).

As shown inFIGS. 8-9, each actuator48includes a lobe51that extends radially outwardly from the actuator axis52or the actuator shaft53. The lobe51terminates at blunt engagement surface61, which engages the friction ring41and pushes the friction ring41into the recess42of the gear22when the shift sleeve35moves to the right inFIGS. 1-4. Further, the blunt engagement surface61engages the friction ring43and pushes the friction ring43into the recess44of the gear25when the shift sleeve35moves to the left inFIGS. 1-4. The actuators48each include an offset pin62that is received in a recess63disposed in the shift sleeve35(seeFIG. 1), which enables the rotational movement of the lobe51into engagement with either the friction ring41or the friction ring43. Because the offset pin62is not coaxial with the actuator axis52, movement of the shift sleeve35in an axial direction either to the right or to the left inFIG. 1causes the actuator48to rotate about the actuator axis52. When the shift sleeve35moves to the right inFIG. 1, the actuator48rotates to the right so that the blunt engagement surface61of the lobe51engages the friction ring41and pushes the friction ring41into the recess42of the gear22as shown inFIG. 2.

InFIG. 2, the lobes51have pushed the friction ring41into the recess42of the gear22to an extent where the outer conical surface64of the friction ring41is in frictional contact with a conical surface65of the recess42. In the position shown inFIG. 2, the frictional engagement between the outer conical surface64and the conical surface65causes the gear22to rotate with the transmission shaft21and the actuator carrier28and therefore synchronizes the gear22with the transmission shaft21. The synchronizing of the rotational speeds of the gear22and transmission shaft21(FIG. 2) occurs prior to engagement of the pawls23of the actuators48with the clutch teeth24disposed on the gear22(FIG. 4).

The friction rings41,43also rotate with the actuator carrier28and the transmission shaft21due to the connection between the friction rings41,43and the actuator carrier28as illustrated inFIG. 7. Referring toFIG. 7, the actuator carrier28includes a lug66. Further, the friction ring43, which may be identical in construction to the friction ring41, is a split ring with two free ends67,68. The friction ring41is held in place by the recess44as shown inFIG. 1and the engagement between the lug66and the free ends67,68of the friction ring43enable the friction ring43to rotate in either direction with the actuator carrier28. An identical lug (not shown) couples the friction ring41for rotation with the actuator carrier28as well.

Returning toFIG. 8, each actuator48includes a pawl23, which, like the lobe51, extends radially outwardly from the actuator axis52or the actuator shaft53. In the embodiment shown inFIGS. 8-9, the pawl23extends radially outwardly and terminates at an acute edge69. The acute edge69of the pawl23of the actuator48engages one side of a clutch tooth24as shown inFIG. 6.FIG. 6is an illustration of a full engagement between the actuators48and the clutch teeth24.FIG. 4also illustrates this fully engaged position.FIG. 5illustrates the actuators48in their neutral position, also shown inFIG. 1.FIG. 3, in contrast, shows the actuators48in a position just prior to full engagement of the pawls23with the clutch teeth24.

Returning toFIG. 2, during synchronization of the gear22with the transmission shaft21, the friction ring41has expanded due to the frictional contact between the outer conical surface64of the friction ring41and the conical surface65of the recess42of the gear22. This causes the friction ring41to expand and prevents further rotation of the actuators48until synchronization is complete. After synchronization is complete, the friction ring41shrinks and can be pushed farther into the recess42to the position shown inFIGS. 3 and 4.FIGS. 3 and 4illustrate the friction ring41at its deepest position within the recess42and the size of the lobe51prevents any further biasing or pushing of the friction ring41into the recess42. As the actuator48rotates further, the pawls23of the actuator48then engage the clutch teeth24of the gear22. Thus, inFIG. 4, the module20fully engages the gear22and both rotation and torque is transmitted from the transmission shaft21to the gear22.

Returning toFIGS. 5-6, each window47may include two actuators48with the pawls23disposed in opposing directions. Further, the clutch teeth24may include angled side edges71,72for engaging oppositely directed pawls23of two actuators48disposed at opposite ends of a window47.FIGS. 5-6also illustrate the recesses63that accommodate the offset pins62of two actuators48disposed at opposite ends of a window47.FIG. 7illustrates a coupling between the actuator carrier28and the shift sleeve35. Specifically, the actuator carrier28may include a plurality of radially outwardly extending tongues73that are each accommodated in an axially extending groove74thereby providing a tongue-in-groove connection with permits movement of the shift sleeve35along the transmission shaft axis58while the shift sleeve35rotates with the actuator carrier28.

FIGS. 10-11illustrate an alternative actuator148wherein the offset pin162is disposed on a lever169that extends outward from the shaft153or outward from the outer end155of the shaft153. The shaft153also includes an inner end154and the actuator148, like the actuator48shown inFIGS. 8-9, includes a lobe151and a pawl123. The lobe151includes a blunt engagement surface161and the pawl123includes an acute edge168, similar to the actuator48shown inFIGS. 8-9.

INDUSTRIAL APPLICABILITY

The disclosed clutch and gear synchronizer module20includes one or more actuators48that extend radially outward from the transmission shaft axis58or radially between the inner hub27and the outer ring45of the actuator carrier28. While the actuators48are disposed radially with respect to the transmission shaft21, they rotate about an actuator axis52that is perpendicular to the transmission shaft axis58. The actuators48may include a shaft53or similar structure that provides an inner end54that may be received in an inner recess56disposed in the inner hub27of the actuator carrier28. The actuator48may further include an outer end55that may be received in an through hole57disposed in the outer ring45of the actuator carrier28. This rotatable connection between the actuators48and the actuator carrier28provides for a reliable connection between the actuator48and the actuator carrier28that is also easy to assemble. Employment of offset pins62that are securely coupled to the shift sleeve35enables the lateral or axial movement of the shift sleeve35along the transmission shaft axis58to cause the actuators48to rotate about their actuator axes52, which results in the lobes51engaging the friction ring41when the shift sleeve35is shifted to the right inFIGS. 1-4or the lobe51engaging the friction ring43when the shift sleeve35is shifted to the left inFIGS. 1-4. The arrangement of the friction rings41,43in the recesses42,44of the gears22,25respectively enables the synchronizing function illustrated inFIG. 2to occur prior to the engagement of the pawls23with the clutch teeth24. The disclosed clutch and gear synchronizer module20is easy to assembly and install between two gears25,22.

A method for synchronizing a rotational speed of the gear22with the rotational speed of a transmission shaft21and for transferring torque from the transmission shaft21to the gear22may include the following steps. First, the gear22includes an annular surface76that includes a circular pattern of clutch teeth24as illustrated inFIGS. 1-6. The method may further include providing a clutch and gear synchronizer module20that includes an actuator carrier28disposed radially within and coupled to a shift sleeve35. The module20may also include a friction ring41or other suitable friction element coupled to the actuator carrier28for rotation with the actuator carrier28. The actuator carrier28may include an inner hub27connected to an outer ring45with a window47disposed between the inner hub27and the outer ring45. The module20may further include an actuator48that extends radially between the inner hub27and the outer ring45and across the window47. The actuator48may include a lobe51and a pawl23disposed in radial alignment with the window47and with the lobe51also in radial alignment with the friction ring41and with the pawl23in radial alignment with the circular pattern of clutch teeth24of the gear22. The actuator48may further include an outwardly directed offset pin62that is parallel to but not coaxial with the actuator axis52. The offset pin62may couple to the shift sleeve35so that axial movement of the shift sleeve35causes rotation of the actuator48.

The method may further include mounting the module20on the transmission shaft21for rotation with the transmission shaft21. The method may further include passing the transmission shaft21through the gear22so the gear22is disposed adjacent to the module20. The method may further include moving shift sleeve35and offset pin62towards the gear22an initial distance thereby causing the lobe51to rotate into engagement with the friction ring41and push the friction ring41into the circular recess42of the gear22(seeFIG. 2) thereby causing the gear22to rotate with the module20and the transmission shaft21. The method may further include moving the shift sleeve35and offset pin62further towards the gear22thereby causing the pawl23to rotate into engagement with the circular pattern of clutch teeth24of the gear22for full engagement between the gear22and the module20and the transmission shaft21(SeeFIG. 4).

While only certain embodiments have been set forth, alternatives and modifications will be apparent from the above description to those skilled in the art. These and other alternatives are considered equivalents and within the spirit and scope of this disclosure and the appended claims.