A GEAR SHIFTING DEVICE, A TRANSMISSION AND A METHOD FOR ASSEMBLING A TRANSMISSION

Abstract

A gear shifting device for a transmission of a vehicle has a rod configured to be connected to an actuator for moving the rod along a longitudinal axis of the rod, and a set of shift forks comprising a first shift fork and a second shift fork, the first and second shift forks being fixed to the rod so as to be actuated in unison. The rod has a first part and a second part configured to be mechanically connected to each other via at least one connection interface, wherein the first shift fork is fixed to the first part of the rod and the second shift fork is fixed to the second part of the rod.

Claims

1. A gear shifting device for a transmission of a vehicle, comprising: a rod configured to be connected to an actuator for moving the rod along a longitudinal axis of the rod, a set of shift forks comprising a first shift fork and a second shift fork, the first and second shift forks being fixed to the rod so as to be actuated in unison, characterized in that the rod comprises a first part and a second part configured to be mechanically connected to each other via at least one connection interface, wherein the first shift fork is fixed to the first part of the rod and the second shift fork is fixed to the second part of the rod, wherein the first part of the rod comprises a first interlocking member and the second part of the rod comprises a second interlocking member, wherein the first and second interlocking members constitute the connection interface, and are configured to, when interlocked, prevent relative movement of the first and second parts along the longitudinal axis, and wherein the interlocking members are configured to be interlocked by moving one of the interlocking members in a transverse direction into or onto the other interlocking member.

2. (canceled)

3. (canceled)

4. The gear shifting device according to claim 1, wherein the interlocking members are configured to be prevent relative rotation of the first and second parts.

5. The gear shifting device according to claim 1, wherein the first shift fork comprises a first rod-connecting portion and at least one first engagement member for engaging with a first gear engaging sleeve, and wherein the second shift fork comprises a second rod-connecting portion and at least one second engagement member for engaging with a second gear engaging sleeve, wherein the first shift fork and the second shift fork are bent such that, when the first and second parts of the rod are connected, a first axial distance between the first and second rod connecting portions differs from a second axial distance between the first and second at least one engagement members.

6. The gear shifting device according to claim 1, wherein the rod further comprises a third part and wherein the set of shift forks further comprises a third shift fork fixed to the third part of the rod, wherein the third part is mechanically connected to the first and second parts.

7. A transmission configured for transmission of torque via a set of selectively engageable gears, the transmission comprising a gear shifting device according to any one of the preceding claims claim 1, the transmission further comprising: a transmission housing comprising a first housing portion and a second housing portion, the second housing portion being fixed to the first housing portion, a transmission control unit fixed to the first housing portion and an actuator controllable by the transmission control unit for moving the rod along its longitudinal axis, the actuator being rigidly connected to the first part of the rod, wherein the second housing portion comprises a recess in which an end portion of the second part of the rod is slidably received.

8. The transmission according to claim 7, wherein the first housing portion comprises a through-hole or bracket through which the second part of the rod extends and in which it is slidably received.

9. The transmission according to claim 7, further comprising a gearwheel or a set of gearwheels being rotatably arranged on a shaft, the gearwheel or the set of gearwheels being selectively engageable for transmission of torque by means of the set of shift forks, each gearwheel comprising at least one annular pocket centred on the shaft, wherein each shift fork is configured to be movable by the rod to a position in which it extends into a respective one of the at least one annular pocket.

10. The transmission according to claim 9, wherein the gearwheel or the set of gearwheels comprise at least a first and a second annular pocket opening in opposite directions, the first shift fork being movable to a position in which it extends into the first annular pocket and the second shift fork being movable to a position in which it extends into the second annular pocket.

11. The transmission according to claim 10, wherein the first and second annular pockets are provided on the same gearwheel, or wherein the first and second annular pockets are provided on different gearwheels.

12. The transmission according to claim 7, further comprising a set of gear engaging sleeves, each gear engaging sleeve being movable by a respective one of the shift forks.

13. A method for assembling a transmission according to claim 7, the method comprising: pre-assembling the first part of the rod and the first shift fork with the transmission control unit and the actuator, pre-assembling the second part of the rod and the second shift fork, mounting the second part of the rod and the second shift fork pre-assembled therewith to the first housing portion with the second part of the rod extending through a through-hole or bracket of the first housing portion, the second shift fork and an interlocking member of the second part being provided on opposite sides of the through-hole or bracket, assembling the second housing portion with the first housing portion so that the end portion of the second part of the rod is slidably received in the recess, mounting the transmission control unit and the actuator with the first part of the rod and the first shift fork pre-assembled therewith onto the first housing portion into which the second part of the rod extends, thereby connecting the first and second parts of the rod via the first connection interface.

14. The method according to claim 13, wherein mounting the transmission control unit onto the first housing portion comprises moving one of the transmission control unit and the first housing portion toward the other one of the transmission control unit and the first housing portion in a direction perpendicular to the longitudinal axis of the rod.

15. A vehicle comprising a transmission according to claim 7.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

[0045] In the drawings:

[0046] FIG. 1 illustrates a vehicle according to an embodiment of the invention,

[0047] FIG. 2 is a partly exploded perspective view of a gear shifting device according to an embodiment of the invention,

[0048] FIG. 3 is another perspective view of the gear shifting device shown in FIG. 2,

[0049] FIG. 4 is a side view of the gear shifting device shown in FIG. 2,

[0050] FIG. 5 is a sectional view of parts of a transmission according to an embodiment of the invention, and

[0051] FIG. 6 is a flow chart illustrating a method according to an embodiment of the invention.

[0052] The drawings show diagrammatic exemplifying embodiments of the present invention and are thus not necessarily drawn to scale. It shall be understood that the embodiments shown and described are exemplifying and that the invention is not limited to these embodiments. It shall also be noted that some details in the drawings may be exaggerated in order to better describe and illustrate the invention. Like reference characters refer to like elements throughout the description, unless expressed otherwise.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

[0053] A vehicle 1 in the form of a truck in which a gear shifting device according to the invention may be applied is schematically shown in FIG. 1. The vehicle 1 includes a powertrain with an internal combustion engine 2 for propulsion of the vehicle 1, connected to a transmission 200. The transmission 200 is arranged to transfer torque from the engine 2 to a drive shaft 3 connecting the transmission 200 to a driven axle 4 that drives ground engaging members in the form of wheels 5 of the vehicle 1. The vehicle 1 may be arranged with more than one driven axle, such as two or more driven axles. Instead of, or in addition to, an internal combustion engine 2, the vehicle may comprise one or more electric machines for powering the vehicle.

[0054] FIGS. 2-3 show a gear shifting device 100 according to an embodiment of the invention. The gear shifting device 100 may by way of example be used in the transmission 200 illustrated in FIG. 1. It comprises a rod 110 extending along a longitudinal axis A. The rod 110 is configured to be connected to an actuator 131, such as a pneumatic or electric actuator, for moving the rod 110 back and forth along the longitudinal axis A. The rod 110 comprises a first part 111 and a second part 112, mechanically connectable via a connection interface 113. The gear shifting device 100 further comprises a set of shift forks 121, 122 including a first shift fork 121 and a second shift fork 122. The first shift fork 121 is fixed to the first part 111 of the rod 110, and the second shift fork 122 is fixed to the second part 112 of the rod 110. When the first part 111 and the second part 112 are connected via the connection interface 113, the first and second shift forks 121, 122 can be actuated in unison, i.e., moved simultaneously, along the longitudinal direction A, by means of the actuator 131 acting on the rod 111.

[0055] The first part 111 of the rod 110 is herein fixed to the actuator 131 at a first end portion 111a of the first part 111. A second end portion 111b of the first part 111 comprises a first interlocking member 114 configured to be received in a second interlocking member 115 provided on a first end portion 112a of the second part 112. The first and second interlocking members 114, 115 are configured to, when interlocked, prevent relative movement of the first and second parts 111, 112 along the longitudinal axis A. Interlocking is achieved by moving the first interlocking member 114 into the second interlocking member 115 in a transverse direction B, perpendicular to the longitudinal direction A. FIG. 2 shows the gear shifting device 100 prior to connecting the first and second parts 111, 112. FIG. 3 shows the gear shifting device 100 after connection of the first and second parts 111, 112.

[0056] In the illustrated embodiment, the second interlocking member 115 is illustrated as a female interlocking member and the first interlocking member 114 is illustrated as a male interlocking member, although other configurations are of course possible, as long as relative axial movement of the parts 111, 112 along the axis A is prevented. In the shown embodiment, the interlocking members 114, 115 are further formed with interlocking surfaces that prevent relative rotation of the parts 111, 112 around the longitudinal axis A.

[0057] The first and second shift forks 121, 122 are configured to engage a first and second gear engaging sleeve 151, 152, respectively. For this purpose, the first shift fork 121 comprises three first engagement members 123 and the second shift fork comprise three second engagement members 127, for engaging with an annular groove 153, 158 of the respective sleeve 151, 152. The three first engagement members 123 of the first shift fork 121 are located on a first lower fork portion 125 of the first shift fork 121 and the three second engagement members 127 of the second shift fork 122 are located on a second lower fork portion 128 of the second shift fork 122. Although three engagement members 123, 127 per shift fork 121, 122 are illustrated herein, a different number of engagement members may be provided, such as two engagement members per shift fork.

[0058] The first shift fork 121 further has a first rod-connecting portion 124 attached to the first part 111 of the rod 110, herein close to the first interlocking member 114. The first shift fork 121 is further bent so that, when seen in a side view such as shown in FIG. 4, the first engagement members 123 are axially offset with respect to the first rod-connecting portion 124. The second shift fork 122 has a second rod-connecting portion 126 attached to the second part 112 of the rod 110. The first shift fork 121 and the second shift fork 122 are bent such that, when the first and second parts 111, 112 of the rod 110 are connected, a first axial distance x1 between the first and second rod connecting portions 124, 126 differs from a second axial distance x2 between the first engagement members 123 and the second engagement members 127. In the shown embodiment, the first axial distance x1 is larger than the second axial distance x2, although the opposite is also possible in other configurations.

[0059] When the first shift fork 121 is connected to the first gear engaging sleeve 151, the first gear engaging sleeve 151 herein lies axially further away from the actuator 131 than the first rod-connecting upper portion 124. The second shift fork 122 is bent in the opposite direction, so that when it engages with the second gear engaging sleeve 152, and when the first and second parts 111, 112 of the rod 110 are connected, the second gear engaging sleeve 152 is axially closer to the actuator 131 than the rod-connecting upper portion 126 of the second shift fork 122. The shift forks 121, 122 are thus bent toward one another.

[0060] Reference is now made to FIGS. 4 and 5, showing the gear shifting device 100 together with a gearwheel 240 of a transmission 200. The gearwheel 240 is rotatably arranged on a shaft (not shown) extending along an axis C, which is parallel with the longitudinal axis A. The gearwheel 240 is selectively engageable for transmission of torque by means of the set of shift forks 121, 122 acting on the sleeves 151, 152. The gearwheel 240 comprises an annular gear tooth portion 243 comprising a plurality of external gear teeth 246, and an annular inner flange portion 244 provided radially inside of the gear tooth portion 243 and rigidly connected to the gear tooth portion 243 by an annular connecting portion 245. Two annular pockets 241, 242 facing in opposite directions along the longitudinal axis A are formed between the inner flange portion 244 and the gear tooth portion 243. A first annular pocket 241 is provided on a first side of the gearwheel 240, facing the first shift fork 121. A second annular pocket 242 is provided on a second side of the gearwheel 240, facing the second shift fork 122.

[0061] The first shift fork 121 and the first gear engaging sleeve 151 are movable by the rod 110 to a position in which the first shift fork 121 extends into the first annular pocket 241. The second shift fork 222 and the second gear engaging sleeve 152 are movable by the rod 110 to a position in which the second shift fork 222 extends into the second annular pocket 242. The first and second shift forks 121, 122 are movable in unison, such that when the first shift fork 121 and the first gear engaging sleeve 151 is moved into the first annular pocket 241, the second shift fork 122 and the first gear engaging sleeve 152 are moved out of the second annular pocket 242, and vice versa. In FIG. 5, the first gear engaging sleeve 151 rotationally connects the gearwheel 240 to an adjacent gearwheel 250, while the second gear engaging sleeve 152 is located entirely within the second annular pocket 242. By moving the rod 110 one step to the left, a neutral position can be achieved, in which none of the gear engaging sleeves 151, 152 engages a gear. By moving the rod 110 two steps to the left, the second gear engaging sleeve 152 rotationally connects the gearwheel 240 to the shaft via a component fixed to the shaft, while the first gear engaging sleeve 151 is entirely located within the first annular pocket 241.

[0062] FIG. 5 is a sectional view showing parts of a transmission 200, such as the transmission 200 referred to above. The transmission 200 is configured for transmission of torque via a set of selectively engageable gears, such as between an input shaft and an output shaft (not shown). The transmission 200 includes a transmission housing 220 comprising a first housing portion 221 and a second housing portion 222, the second housing portion 222 being fixed to the first housing portion 221. A transmission control unit 130 is fixed to the first housing portion 221. The actuator 131 is controllable by the transmission control unit 130 for moving the rod 110 in the axial direction. The actuator 131 is rigidly connected to the first part 111 of the rod 110. The second housing portion 222 comprises a recess 223 in which a second end portion 112b of the second part 112 of the rod 110 is slidably received. The first housing portion 221 further comprises a through-hole 224, which may alternatively be a bracket fixed to the first housing portion 221, through which the second part 112 of the rod 110 extends and in which it is slidably received. The second shift fork 122 is positioned on a second side of the through-hole 224, on the same side of the through-hole 224 as the recess 223.

[0063] FIG. 6 illustrates a method for assembling a transmission 200, such as the transmission 200 illustrated in FIG. 5.

[0064] In a first step S1, the first part 111 of the rod 110 and the first shift fork 121 are pre-assembled with the transmission control unit 130 and the actuator 131.

[0065] In a second step S2, the second part 112 of the rod 110 and the second shift fork 122 are pre-assembled.

[0066] The first and second steps may be carried out in any suitable order. Pre-assembled parts may be delivered from other locations and the first and second steps may thus not necessarily be carried out in connection with subsequent steps.

[0067] In a third step S3, the second part 112 of the rod 110 and the second shift fork 122 pre-assembled therewith are mounted to the first housing portion 221 with the second part 112 of the rod 110 extending through the through-hole 224, or bracket. The second shift fork 122 and the second interlocking member 115 are, after mounting, provided on opposite sides of the through-hole 224 or bracket. At least the second interlocking member 115 is located within the first housing portion 221. Other components of the transmission 200, such as shafts, gearwheels, etc., may be mounted into the first housing portion 221 in connection with, or prior to, the third step S3. For example, the gearwheel 240 and the gear engaging sleeves 151, 152, provided on a shaft, may be mounted into the first housing portion 221, and the second shift fork 122 may be engaged with the second gear engaging sleeve 152 in its position outside of the second annular pocket 242.

[0068] In a fourth step S4, the second housing portion 222 is assembled with the first housing portion 221 so that the second end portion 112b of the second part 112 of the rod 110 is slidably received in the recess 223.

[0069] In a fifth step S5, the transmission control unit 130 and the actuator 131, with the first part 111 of the rod 110 and the first shift fork 121 pre-assembled therewith, are mounted onto the first housing portion 221 into which the second part 112 of the rod 110 extends. Thereby, the first and second parts 111, 112 of the rod 110 are connected via the first connection interface 113. To successfully perform this step, the second part 112 of the rod 110 is first moved along the axial direction A so that the second shift fork 122 and the second gear engaging sleeve 152 enter into the second annular pocket 242. The first gear engaging sleeve 151 is positioned outside of the first annular pocket 241, which allows the first shift fork 121 to engage with the first gear engaging sleeve 151 when moved in the transverse direction B. Thus, the first shift fork 121 engages with the first gear engaging sleeve 151 at the same time as the first part 111 of the rod 110 connects to the second part 112 of the rod via the connection interface 113.

[0070] In non-illustrated embodiments of the invention, the rod is divided into more than two parts, such as into three parts. Each part carries at least one shift fork. A connection interface is provided between each two parts. For three parts, two connection interfaces are provided.

[0071] The shift forks are in the illustrated embodiment configured to engage with gear engaging sleeves acting on the same gearwheels. However, the shift forks may also be configured to move gear engaging sleeves acting on different gearwheels, provided on the same shaft or even on different shafts. For example, if two input shafts are provided, two shift forks may be provided that are configured to simultaneously act on gearwheels on different input shafts.

[0072] It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.