WO2018210400A1

WO2018210400A1 - A transmission for a vehicle

Info

Publication number: WO2018210400A1
Application number: PCT/EP2017/061590
Authority: WO
Inventors: Per Mattsson; Jan Dersjö
Original assignee: Volvo Construction Equipment Ab
Priority date: 2017-05-15
Filing date: 2017-05-15
Publication date: 2018-11-22

Abstract

The present invention relates to a transmission arrangement (100) for a vehicle, the transmission arrangement comprising a primary transmission arrangement (200), a transmission housing (160), an input shaft (136), and an output shaft (112), the primary transmission arrangement (200) comprising a first (102), a second (104), a third (106) and a fourth (108) planetary gear set each comprising a sun gear, a planet carrier and a ring gear, wherein the primary transmission arrangement (200) further comprises five shift elements (138, 142, 144, 146, 150) engageable in combinations of two to obtain six forward gear stages, wherein the input shaft (136) is operatively connected to the sun gear (106S) of the third planetary gear set (106) and to the ring gear (108R) of the fourth planetary gear set (108).

Description

A TRANSMISSION FOR A VEHICLE

TECHNICAL FIELD

The present invention relates to a transmission of a vehicle. The invention also relates to a vehicle comprising such a transmission. The invention is applicable on vehicles, in particularly working machines such as e.g. wheel loaders, articulated haulers, dump trucks, etc. Although the invention will mainly be described in relation to a wheel loader, it may also be applicable for other type of vehicles. BACKGROUND

In connection with transportation of heavy loads at construction sites or the like, a working machine is often used. The working machines may be utilized for transportations in connection with road or tunnel building, sand pits, mines, forestry and similar environments. Thus, the working machine is frequently operated with large and heavy loads in rough terrain and on slippery ground where no regular roads are present.

In order to fulfil the desired demands from the fields where the working machine is frequently operated, high quality of the vehicle gearbox is necessary. The gearbox is arranged for adjusting the speed and tractive effort of the vehicle in dependency of the specific driving scenario. The gearbox comprises a transmission arrangement and depending on the specific type of gearbox, the transmission arrangement may comprise e.g. ordinary gear sets with cylindrical gear wheels in meshed connection with each other or planetary gear sets comprising a respective sun gear, ring gear and a planet carrier, or a transmission having a combination of ordinary gear sets and one or more planetary gear sets.

According to prior art solutions, transmissions are often arranged to obtain a plurality of gear stages, both forward gear stages and reverse gear stages. For obtaining these gear stages, the transmission is often associated with a large number of transmission components, such as gear wheels, shafts and shift elements. For many applications, the large number of gear stages may be superfluous as some of the gear stages may be rarely used. There is thus a desire to provide a transmission arrangement arranged to obtain a sufficient number of gear stages with a reduced number of transmission

components. SUMMARY

It is an object of the present invention to provide a transmission arranged to obtain a sufficient number of gear stages by using a reduced number of transmission components in comparison to the prior art. The object is at least partly achieved by a transmission according to claim 1 .

According to a first aspect of the present invention, there is provided a transmission arrangement for a vehicle, the transmission arrangement comprising a primary transmission arrangement, a transmission housing, an input shaft, and an output shaft, the primary transmission arrangement comprising a first, a second, a third and a fourth planetary gear set each comprising a sun gear, a planet carrier and a ring gear, wherein the primary transmission arrangement further comprises five shift elements engageable in combinations of two to obtain six forward gear stages, wherein the input shaft is operatively connected to the sun gear of the third planetary gear set and to the ring gear of the fourth planetary gear set.

The wording "operatively connected to" should in the following and throughout the entire description be interpreted such that the components thereof are fixedly connected to each other, i.e. the rotational speed of the components which are operatively connected to each other is the same. Hence, no connecting mechanism or the like is arranged between the components that are operatively connected to each other and they can therefore not be disengaged from one another during operation. Accordingly, the input shaft is always connected to the sun gear of the third planetary gear set and to the ring gear of the fourth planetary gear set. The present invention is based on the insight that by providing the above described primary transmission arrangement, an advantageous transmission for achieving forward gears is obtained. An advantage is thus that a few number of transmission components, such as only five shift elements, is needed for obtaining the six forward gear stages. In particular, only five valves for controlling the shift elements are needed. Also, as each of the six forward gear stages only requires two shift elements to be engaged, a low number of shift elements need activation for each of the forward gears. Moreover, when executing one-step gear shifts, as well as executing two-step gear shifts, only one of the shift elements needs to be shifted from a disengaged state to an engaged state, and only one of the shift elements needs to be shifted from an engaged state to a disengaged state. One-step gear shifts should be understood to mean that a gear shift is executed from one gear stage to the next coming consecutive gear stage, for example, gear shift from the first gear stage to the second gear stage. Two-step gear shifts on the other hand should be understood to mean that a gear shift is executed to exclude a next coming consecutive gear stage, for example, gear shift from the first gear stage to the third gear stage.

A still further advantage is that the primary transmission arrangement can be connected to a suitable additional transmission arrangement for achieving reverse gears, as will be described further below. Hereby, the primary transmission arrangement only obtains forward gears and, depending on the specific intended use of the transmission, a suitable additional transmission arrangement for the reverse gears can be used. Accordingly, the primary transmission arrangement can serve as a substantially universal forward gear transmission arrangement. According to an example embodiment, the five shift elements may comprise two locking mechanisms and three connecting mechanisms.

A locking mechanism should be construed as a shift element which locks e.g. a planetary member of one of the planetary gear sets to the transmission housing. Hence, when a locking mechanism is positioned in the engaged state, the planetary member connected thereto is held stationary. A connecting mechanism on the other hand should be construed as a shift element which connects e.g. two planetary members to each other, or connects a planetary member to the input shaft or the output shaft of the transmission. Hereby, the members on a respective side of the connecting mechanism rotate with the same rotational speed when the connecting mechanism is positioned in the engaged state. The locking mechanisms and the connecting mechanisms may also be positioned in a slipping state, whereby a relative rotational speed is obtained between the members connected thereto. According to an example embodiment, the input shaft and the planet carrier of the fourth planetary gear set may be selectively connectable to each other.

The wording "selectively connectable to" should in the following and throughout the entire description be interpreted as an element being connectable at desirable points in time to another element. Hereby, gear shifts of the transmission arrangement can be executed by either connecting or disconnecting elements to/from each other. Components may be selectively connectable to each other by means of

connecting/locking mechanisms and controlled by e.g. a control unit or the like. When a connecting/locking mechanism is positioned in an engaged state the components are connected to each other.

According to an example embodiment, the output shaft and the planet carrier of the first planetary gear set may be operatively connected to each other.

According to an example embodiment, the sun gear of the first planetary gear set and the sun gear of the second planetary gear set may be operatively connected to each other. According to an example embodiment, the ring gear of the first planetary gear set and the planet carrier of the second planetary gear set may be operatively connected to each other.

According to an example embodiment, the ring gear of the second planetary gear set and the planet carrier of the third planetary gear set may be operatively connected to each other.

According to an example embodiment, the ring gear of the third planetary gear set and the sun gear of the fourth planetary gear set may be operatively connected to each other.

According to an example embodiment, at least one of the sun gear of the first planetary gear set and the sun gear of the second planetary gear set may be selectively connectable to the transmission housing. According to an example embodiment, at least one of the ring gear of the first planetary gear set and the planet carrier of the second planetary gear set may be selectively connectable to the sun gear of the third planetary gear set. According to an example embodiment, at least one of the sun gear of the fourth planetary gear set and the ring gear of the third planetary gear set may be selectively connectable to the planet carrier of the second planetary gear set.

According to an example embodiment, at least one of the sun gear of the fourth planetary gear set and the ring gear of the third planetary gear set may be selectively connectable to the transmission housing.

According to an example embodiment, the transmission arrangement may further comprise an additional transmission arrangement operatively connected to the first planetary gear set of the primary transmission arrangement for obtaining at least one reverse gear stage.

Hereby, at least one reverse gear for the transmission is obtained. The primary transmission arrangement can thus, as described above, serve as a substantially universal forward gear transmission arrangement which is here complemented by reverse gear functionality.

According to an example embodiment, the additional transmission arrangement may be operatively connected to the planet carrier of the first planetary gear set.

According to an example embodiment, the additional transmission arrangement may comprise a plurality of gear wheels arranged in meshed connection and arranged on respective radially separated transmission shafts, wherein the additional

transmission arrangement comprises an additional pair of shift elements connected to a respective one of the transmission shafts for obtaining forward gears and reverse gears.

Hereby, a so-called drop box, which can transmit torque from a prime mover to a lower elevated level, can be provided. Such drop box is particularly suitable to use in wheel loader applications. According to an example embodiment, the additional transmission arrangement may comprise a first transmission shaft connected to the first planetary gear set of the primary transmission arrangement, the first transmission shaft comprising a first gear wheel fixedly connected to the first transmission shaft, a first running gear wheel and a first clutch arrangement, wherein the first clutch arrangement is arranged to selectively connect the first running gear wheel to the first transmission shaft.

The wording "fixedly connected to" should be understood to mean that the gear wheel rotates with the shaft it is connected to. Such gear wheel may, for example, be press-fitted to the shaft. A running gear wheel on the other hand should be understood to mean that the gear wheel is connected to the shaft via a bearing arrangement, whereby a clutch selectively connects the gear wheel to the shaft. According to an example embodiment, the additional transmission arrangement may comprise a second transmission shaft comprising a second gear wheel fixedly connected to the second transmission shaft, wherein the second gear wheel is arranged in meshed connection with the first running gear wheel of the first transmission shaft.

According to an example embodiment, the additional transmission arrangement may comprise a third transmission shaft comprising a third gear wheel fixedly connected to the third transmission shaft, a second running gear wheel and a second clutch arrangement, wherein the second clutch arrangement is arranged to selectively connect the second running gear wheel to the third transmission shaft.

According to an example embodiment, the third gear wheel may be arranged in meshed connection with the second gear wheel, and the second running gear wheel may be arranged in meshed connection with the first gear wheel.

According to an example embodiment, the third gear wheel may be arranged in meshed connection with the first gear wheel, and the second running gear wheel may be arranged in meshed connection with the second gear wheel. According to an example embodiment, the additional transmission arrangement may comprise an output shaft gear wheel arranged on an output shaft of the primary transmission arrangement, the output shaft gear wheel being arranged in meshed connection with the first gear wheel arranged on the first transmission shaft.

According to a second aspect of the present invention, there is provided a vehicle comprising a prime mover and a gearbox, wherein the gearbox comprises a transmission arrangement according to any one of the example embodiments described above in relation to the first aspect.

Effects and features of the second aspect are largely analogous to those described above in relation to the first aspect.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled person will realize that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention.

DEFINITIONS

The relationship between the rotational speeds of the different members in a planetary gear set is defined according to the following:

= R (Eq. 1 ) wherein ω₅ is the speed of rotation of the sun gear;

ω_Ρ is the speed of rotation of the planet carrier;

ω_κ is the speed of rotation of the ring gear; and

R is the stationary gear ratio of the planetary gear set.

As used herein, the expression "stationary gear ratio" fi for a planetary gear set is defined as the ratio of the speed of rotation of the sun gear to the speed of rotation of the ring gear in a situation in which the planet carrier is stationary, i.e.: for single planet gear wheels (Eq. 2) and for double planet gear wheels (Eq. 3)

wherein z_R is the number of teeth of the ring gear; and

z_s is the number of teeth of the sun gear.

In a similar manner, the expression "ratio" for a transmission should be understood to relate to the number of revolutions of the input shaft of the transmission divided by the number of revolutions of the output shaft of the transmission. Furthermore, the expression "step" should be understood to mean the quotient achieved when the ratio of a gear is divided by the ratio of an adjacent gear of a transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of exemplary embodiments of the present invention, wherein:

Fig. 1 is a lateral side view illustrating a working machine in the form of a wheel loader;

Fig. 2 schematically illustrates a transmission arrangement according to an example embodiment of the present invention; and

Fig. 3 schematically illustrates a transmission arrangement including a drop box according to an example embodiment of the present invention. DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness. Like reference character refer to like elements throughout the description.

Fig. 1 is a lateral side view illustrating an example embodiment of a working machine in the form of a loader vehicle 1 having an implement 2 for loading operations. The loader vehicle 1 depicted in Fig. 1 is in the form of an articulated wheel loader. The term "implement" is intended to comprise any kind of hydraulically operated tool, such as a bucket, a fork or a gripping tool arranged on the loader vehicle 1 . The implement 2 illustrated in Fig. 1 comprises a bucket 3 which is arranged on a loading unit assembly 4 for lifting and lowering the bucket 3. The bucket 3 can also be tilted or pivoted relative to the loading unit assembly 4. The loader vehicle 1 is provided with a hydraulic system comprising at least one hydraulic machine (not shown), such as e.g. a hydraulic pump. The loader vehicle 1 further comprises a hydraulic lift cylinder 5, for lifting operation of the loading unit assembly 4 and a hydraulic tilt cylinder 6 for tilting the bucket 3 relative to the loading unit assembly 4. Furthermore, the hydraulic system comprises steering cylinders 7a, 7b for turning the loader vehicle 1 by means of relative movement of a front unit 8 and a rear unit 9 around a substantially vertical geometric axis 10 of an articulated joint arrangement 12. The front unit 8 and the rear unit 9 comprise a respective pair of ground engaging members 20, 22. The ground engaging members 20, 22 are in the example embodiment a respective pair of wheels. In other words, the loader vehicle 1 is frame-steered by means of the steering cylinders 7a, 7b.

Now, with reference to Fig. 2, an example embodiment of a transmission

arrangement 100 according to the present invention is illustrated. In detail, Fig. 2 illustrates the primary transmission arrangement 200 which comprises a first planetary gear set 102 comprising a sun gear 102S, a planet carrier 102P and a ring gear 102R, a second planetary gear set 104 comprising a sun gear 104S, a planet carrier 104P and a ring gear 104R, a third planetary gear set 106 comprising a sun gear 106S, a planet carrier 106P and a ring gear 106R, and a fourth planetary gear set 108 comprising a sun gear 108S, a planet carrier 108P and a ring gear 108R. The transmission arrangement 100 further comprises an input shaft 136 for receiving a rotary motion/torque from the prime mover (not shown) of the vehicle 1 and an output shaft 1 12 for providing a rotary motion/torque to the driven wheels of the vehicle 1 .

The different members of the planetary gear sets 102, 104, 106, 108 of the primary transmission arrangement 200, i.e. the sun gear, the planet carrier and the ring gear, are in the example embodiment depicted in Fig. 2 configured according to the following. It should be readily understood that the different members described below are connected to each other, either directly, i.e. operatively connected, or via a connecting mechanism, i.e. selectively connectable. The members can be operatively connected to each other by means of e.g. a connector element. Such connector element can be e.g. a solid shaft, a hollow shaft or a drum, or other suitable element for connecting two members to each other, which elements are known to the person skilled in the art. Hence, no explicit explanation is given below in regards to the means connecting the members to each other.

The planet carrier 102P of the first planetary gear set 102 is operatively connected to the output shaft 1 12 of the transmission arrangement 100, i.e. the planet carrier 102P is at all times directly connected to the output shaft 1 12 of the transmission arrangement 100. Further, the ring gear 102R of the first planetary gear set 102 is operatively connected to the planet carrier 104P of the second planetary gear set 104. The sun gear 102S of the first planetary gear set 102 is operatively connected to the sun gear 104S of the second planetary gear set 104. Furthermore, the sun gear 102S of the first planetary gear set 102 and the sun gear 104S of the second planetary gear set 104 are selectively connectable to a transmission housing 160 of the transmission arrangement 100 by means of a first locking mechanism 142.

Hence, the first locking mechanism 142, when being engaged, initially reduces the rotational speed of the respective sun gears 102S, 104S, and thereafter locks the respective sun gears 102S, 104S to the transmission housing.

The ring gear 104R of the second planetary gear set 104 is operatively connected to the planet carrier 106P of the third planetary gear set 106. Furthermore, the planet carrier 104P of the second planetary gear set 104 is selectively connectable to the ring gear 106R of the third planetary gear set 106 by means of a first connecting mechanism 146. The first connecting mechanism 146 can be a clutch arrangement. Furthermore, the planet carrier 104P of the second planetary gear set 104 is also selectively connectable to the sun gear 106S of the third planetary gear set 106 by means of a second connecting mechanism 144. The second connecting mechanism 144 can be a clutch arrangement.

The sun gear 106S of the third planetary gear set 106 is operatively connected to the ring gear 108R of the fourth planetary gear set 108. The ring gear 106R of the third planetary gear set 106 is operatively connected to the sun gear 108S of the fourth planetary gear set 108. The ring gear 106R of the third planetary gear set 106 and the sun gear 108S of the fourth planetary gear set 108 are selectively connectable to the transmission housing 160 by means of a second locking mechanism 138. Hence, the second locking mechanism 138, when being engaged, initially reduces the rotational speed of the ring gear 106R and the sun gear 108S, and thereafter locks the ring gear 106R and the sun gear 108S to the transmission housing 160.

Finally, the input shaft 136 is operatively connected to the ring gear 108R of the fourth planetary gear set 108 and to the sun gear 106S of the third planetary gear set 106, and selectively connectable to the planet carrier 108P of the fourth planetary gear set 108 by means of a third connecting mechanism 150. The third connecting mechanism 150 can be a clutch arrangement.

According to the example embodiment depicted in Fig. 2, the stationary gear ratio of each one of the first 102, second 104, third 106, and fourth 108 planetary gear sets are negative. According to a non-limiting example, the stationary gear ratio for each of the planetary gear sets may be as described below in Table 1 .

Table 1 - Exemplary stationary gear ratios for the embodiment depicted in Fig. 2.

According to the example depicted in Fig. 2, the transmission 100 is adapted to assume the gears as presented in Table 2 below. In Table 2 below, the locking mechanisms are denoted simply as "Brakes" while the connecting mechanisms are denoted simply as "Clutches". A cell marked with a dot indicates an engaged state and a blank cell indicates a disengaged state. The table also indicates non-limiting examples of the gear ratios and steps obtained by the stationary gear ratios in Table 1 .

Table 2 - Shift diagram for the different forward gears of the embodiment in Fig. 2.

As can be seen in Table 2, the transmission 100 in Fig. 2 comprises six forward gear stages F1 - F6, wherein each of the six gear stages is obtained by positioning two of the shift elements in the engaged state. The switching of gears can preferably be executed by one-step gear shifts or with two-step gear shifts. One-step gear shift should be understood to mean that a gear shift is executed from one gear to the next coming consecutive gear, for example, gear shift from the first gear stage to the second gear stage, from the second gear stage to the third gear stage, from the third gear stage to the second gear stage, etc. Two-step gear shift should be understood to mean that a gear shift is executed to exclude a next coming consecutive gear stage, for example, gear shift from the first gear stage to the third gear stage, from the second gear stage to the fourth gear stage, from the third gear stage to the first gear stage, etc.

As can be seen from Table 2, one-step gear shifting includes only single shifts of the connecting mechanisms and the locking mechanisms, i.e. when executing one-step gear shifts, only one of the connecting mechanisms/locking mechanisms is shifted from an engaged state to a disengaged state, and only one of the connecting mechanisms/locking mechanisms is shifted from a disengaged state to an engaged state. As an example, when shifting from the first gear stage to the second gear stage, it is only the second locking mechanism 138 that is changed from an engaged state to a disengaged state, and only the first connecting mechanism 146 that is changed from a disengaged state to an engaged state. Likewise, also two-step gear shifting only includes single shifts of the connecting mechanisms and the locking mechanisms.

An advantage of the transmission arrangement is hence that the shiftability is improved since a low number of connecting mechanisms/locking mechanisms need activation/deactivation during gear shifting. In detail, during both one-step gear shifting as well as during two-step gear shifting, only single shifts occur.

As described above, the primary transmission arrangement 200 assumes forward gear stages for the transmission arrangement 100. Reference is therefore made to Fig. 3 for description of an additional transmission arrangement 600 connected to the primary transmission arrangement 200 for also obtaining reverse gear stages.

Reference is now made to Fig. 3 which schematically illustrates the transmission arrangement 100 according to another example embodiment of the present invention. As can be seen, the transmission arrangement 100 comprises an additional transmission arrangement 600 which is operatively connected to the primary transmission arrangement 200. In detail, the additional transmission arrangement 600 is arranged downstream the primary transmission arrangement 200. Hereby, the additional transmission arrangement 600 is operatively connected between an output shaft 1 12' of the primary transmission arrangement 200 and the output shaft 1 12 of the transmission arrangement 100. The output shaft 1 12' of the primary transmission arrangement 200 may preferably correspond to the output shaft 1 12 depicted and described above in relation to Fig. 2. Accordingly, the additional transmission arrangement 600 is operatively connected to the planet carrier 102P of the first planetary gear set 102.

The additional transmission arrangement 600, which may also be referred to as a drop box, comprises a plurality of gear wheels 602, 604, 606, 608, 610, 612, a plurality of radially separated transmission shafts 1 12', 614, 615, 616, wherein the shaft 615 corresponds to the output shaft 1 12. According to an alternative

embodiment, the shaft 616 may correspond to the output shaft 1 12 of the

transmission arrangement 100. Further, the additional transmission arrangement 600 comprises an additional pair of shift elements 680, 690. The additional pair of shift elements 680, 690 are arranged as a respective connecting mechanism. One of the additional pair of shift elements 680, 690 is a forward shift element 680 and the other one is a reverse shift element 690.

As can be seen in Fig. 3, the additional transmission arrangement 600 comprises an output shaft gear wheel 602 arranged on the output shaft 1 12' of the primary transmission arrangement 200, a first gear wheel 612 arranged on a first

transmission shaft 614 and in meshed connection with the output shaft gear wheel 602, a second gear wheel 606 arranged on a second transmission shaft 615, and a third gear wheel 608 arranged on a third transmission shaft 616. The additional transmission arrangement 600 also comprises a first running gear wheel 604 and a second running gear wheel 610. The first running gear wheel 604 is arranged in meshed connection with the second gear wheel 606 as well as connected to the forward shift element 680, which forward shift element 680 in turn is operatively connected to the first transmission shaft 614. The second running gear wheel 610 is arranged in meshed connection with the first gear wheel 612 as well as connected to the reverse shift element 690, which reverse shift element 690 is operatively connected to the third transmission shaft 616.

By means of the additional transmission arrangement 600 in Fig. 3, the transmission arrangement 100 is provided also with reverse gears stages. The forward and reverse gear stages are assumed by engaging the forward shift element 680 and the reverse shift element 690, respectively. In detail, during the forward gear stages, the forward shift element 680 is positioned in the engaged state and the reverse shift element 690 is positioned in the disengaged state. Hereby, the output shaft 1 12' of the primary transmission arrangement 200 is connected to the first transmission shaft 614 via the output shaft gear wheel 602 and the first gear wheel 612. Also, the forward shift element 680, which is operatively connected to the first transmission shaft 614, is connected to the first running gear wheel 604. Hereby, the first transmission shaft 614 is connected to the second transmission shaft 615 of the transmission arrangement 100 via the second gear wheel 606 and the first running gear wheel 604.

During the reverse gear stages the reverse shift element 690 is positioned in the engaged state and the forward shift element 680 is positioned in the disengaged state. Hereby, the output shaft 1 12' of the primary transmission arrangement 200 is connected to the third transmission shaft 616 via the output shaft gear wheel 602, the first gear wheel 612 and the second running gear wheel 610, and the reverse shift element 690. The third transmission shaft 616 is in turn connected to the second transmission shaft 615 of the transmission arrangement 100 via the second 606 and third 608 gear wheels.

As an additional pair of gear wheels are arranged in meshed connection for the reverse gear stages, the rotational direction of the second transmission shaft 615, i.e. the output shaft 1 12, is opposite for the reverse gear stages in comparison to the forward gear stages. In detail, the rotational direction is changed one additional time for the reverse gear stages in comparison to the forward gear stages.

According to an alternative embodiment not depicted in Fig. 3, the third gear wheel 608 is arranged in meshed connection with the first gear wheel 612, and the second running gear wheel 610 is arranged in meshed connection with the second gear wheel 606.

Furthermore, the additional transmission arrangement 600 may function equally as well without the above described output shaft gear wheel 602. In such case, the first transmission shaft 614 is directly connected to the output shaft 1 12' of the primary transmission arrangement 200.

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. For example, although the present invention has mainly been described in relation to a wheel loader, the invention should be understood to be equally applicable for any type of vehicle.

Claims

1 . A transmission arrangement (100) for a vehicle, the transmission arrangement comprising a primary transmission arrangement (200), a transmission housing (160), an input shaft (136), and an output shaft (1 12), the primary transmission

arrangement (200) comprising a first (102), a second (104), a third (106) and a fourth (108) planetary gear set each comprising a sun gear, a planet carrier and a ring gear, wherein the primary transmission arrangement (200) further comprises five shift elements (138, 142, 144, 146, 150) engageable in combinations of two to obtain six forward gear stages, characterized in that the input shaft (136) is operatively connected to the sun gear (106S) of the third planetary gear set (106) and to the ring gear (108R) of the fourth planetary gear set (108).

2. The transmission arrangement (100) according to claim 1 , wherein the five shift elements (138, 142, 144, 146, 150) comprise two locking mechanisms (138, 142) and three connecting mechanisms (144, 146, 150).

3. The transmission arrangement (100) according to any one of claims 1 or 2, wherein the input shaft (136) and the planet carrier (108P) of the fourth planetary gear set (108) are selectively connectable to each other.

4. The transmission arrangement (100) according to any one of the preceding claims, wherein the output shaft (1 12) and the planet carrier (102P) of the first planetary gear set (102) are operatively connected to each other.

5. The transmission arrangement (100) according to any one of the preceding claims, wherein the sun gear (102S) of the first planetary gear set (102) and the sun gear (104S) of the second planetary gear set (104) are operatively connected to each other.

6. The transmission arrangement (100) according to any one of the preceding claims, wherein the ring gear (102R) of the first planetary gear set (102) and the planet carrier (104P) of the second planetary gear set (104) are operatively connected to each other.

7. The transmission arrangement (100) according to any one of the preceding claims, wherein the ring gear (104R) of the second planetary gear set (104) and the planet carrier (106P) of the third planetary gear set (106) are operatively connected to each other.

8. The transmission arrangement (100) according to any one of the preceding claims, wherein the ring gear (106R) of the third planetary gear set (106) and the sun gear (108S) of the fourth planetary gear set (108) are operatively connected to each other.

9. The transmission arrangement (100) according to any one of the preceding claims, wherein at least one of the sun gear (102S) of the first planetary gear set (102) and the sun gear (104S) of the second planetary gear set (104) is selectively connectable to the transmission housing (160).

10. The transmission arrangement (100) according to any one of the preceding claims, wherein at least one of the ring gear (102R) of the first planetary gear set (102) and the planet carrier (104P) of the second planetary gear set (104) is selectively connectable to the sun gear (106S) of the third planetary gear set (106).

1 1 . The transmission arrangement (100) according to any one of the preceding claims, wherein at least one of the sun gear (108S) of the fourth planetary gear set (108) and the ring gear (106R) of the third planetary gear set (106) is selectively connectable to the planet carrier (104P) of the second planetary gear set (104).

12. The transmission arrangement (100) according to any one of the preceding claims, wherein at least one of the sun gear (108S) of the fourth planetary gear set (108) and the ring gear (106R) of the third planetary gear set (106) is selectively connectable to the transmission housing (160).

13. The transmission arrangement (100) according to any one of the preceding claims, further comprising an additional transmission arrangement (600) operatively connected to the first planetary gear set (102) of the primary transmission arrangement (200) for obtaining at least one reverse gear stage.

14. The transmission arrangement (100) according to claim 13, wherein the additional transmission arrangement (600) is operatively connected to the planet carrier (102P) of the first planetary gear set (102).

15. The transmission arrangement (100) according to any one of claims 13 or 14, wherein the additional transmission arrangement (600) comprises a plurality of gear wheels (604, 606, 608, 610, 612) arranged in meshed connection and arranged on respective radially separated transmission shafts (614, 615, 616), wherein the additional transmission arrangement (600) comprises an additional pair of shift elements (680, 690) connected to a respective one of the transmission shafts (614, 616) for obtaining forward gears and reverse gears.

16. The transmission arrangement (100) according to any one of claims 13 - 15, wherein the additional transmission arrangement (600) comprises a first transmission shaft (614) connected to the first planetary gear set (102) of the primary transmission arrangement (200), said first transmission shaft (614) comprising a first gear wheel (612) fixedly connected to the first transmission shaft (614), a first running gear wheel (604) and a first clutch arrangement (680), wherein the first clutch

arrangement (680) is arranged to selectively connect the first running gear wheel (604) to the first transmission shaft (614).

17. The transmission arrangement (100) according to claim 16, wherein the additional transmission arrangement (600) comprises a second transmission shaft (615) comprising a second gear wheel (606) fixedly connected to the second transmission shaft (615), wherein the second gear wheel (606) is arranged in meshed connection with the first running gear wheel (604) of the first transmission shaft (614).

18. The transmission arrangement (100) according to any one of claims 13 - 17, wherein the additional transmission arrangement (600) comprises a third

transmission shaft (616) comprising a third gear wheel (608) fixedly connected to the third transmission shaft (616), a second running gear wheel (610) and a second clutch arrangement (690), wherein the second clutch arrangement (690) is arranged to selectively connect the second running gear wheel (610) to the third transmission shaft (616).

19. The transmission arrangement (100) according to claim 18 when dependent on claim 17, wherein the third gear wheel (608) is arranged in meshed connection with the second gear wheel (606), and the second running gear wheel (610) is arranged in meshed connection with the first gear wheel (612).

20. The transmission arrangement (100) according to claim 18 when dependent on claim 17, wherein the third gear wheel (608) is arranged in meshed connection with the first gear wheel (612), and the second running gear wheel (610) is arranged in meshed connection with the second gear wheel (606).

21 . The transmission arrangement (100) according to claim 16, wherein the additional transmission arrangement (600) comprises an output shaft gear wheel (602) arranged on an output shaft (1 12') of the primary transmission arrangement (200), said output shaft gear wheel (602) being arranged in meshed connection with the first gear wheel (612) arranged on the first transmission shaft (614).

22. A vehicle comprising a prime mover and a gearbox, wherein the gearbox comprises a transmission arrangement according to any one of the preceding claims.