WO2014185829A1

WO2014185829A1 - Transmission assembly

Info

Publication number: WO2014185829A1
Application number: PCT/SE2013/000076
Authority: WO
Inventors: Jan Dersjö; Per Mattsson; Mathias LEHIKOINEN; Mats ÅKERBLOM; Mirko Leesch; Jörg Müller; Rico Resch
Original assignee: Volvo Construction Equipment Ab
Priority date: 2013-05-15
Filing date: 2013-05-15
Publication date: 2014-11-20

Abstract

The present disclosure relates to a transmission assembly (10) comprising a first (12), a second (14), a third (16) and a fourth (18) planetary gear set, each one of said planetary gear sets (12, 14, 16, 18) comprising a ring gear, a planet carrier and a sun gear, said transmission assembly (10) further comprising a transmission housing (20) and a first (22) and a second (24) transmission shaft.

Description

TRANSMISSION ASSEMBLY

TECHNICAL FIELD

The present disclosure relates to a transmission assembly according to the preamble of claim 1. Moreover, the present disclosure relates to a working machine.

BACKGROUND

A working machine, such as a wheel loader, an articulated hauler or any other type of construction equipment, is generally provided with a transmission assembly in order to control the propulsion of the working machine. A transmission assembly may comprise a plurality of planetary gear sets. Different gears of such a transmission assembly may be obtained by engaging selected components of the planetary gear sets with other components or a transmission housing.

An example of such a transmission assembly is disclosed in US 2010/0184554 A1.

However, the US 2010/0184554 A1 transmission assembly comprises five planetary gear sets and seven connecting or locking mechanisms. The plurality of planetary gear sets and shifting mechanisms results in a relatively complex and expensive transmission assembly.

SUMMARY

One object of the present disclosure is to provide a transmission assembly that is capable of providing an appropriate number of positive and negative gears using an appropriately small number of planetary gear sets and shifting mechanisms. This object is achieved by a transmission assembly according to claim 1.

As such, the present disclosure relates to a transmission assembly comprising a first, a second, a third and a fourth planetary gear set. Each one of the planetary gear sets comprises a ring gear, a planet carrier and a sun gear. The transmission assembly further comprises a transmission housing and a first and a second transmission shaft. The transmission assembly being configured such that: - the planet carrier of the fourth planetary gear set and the ring gear of the first planetary gear set are operatively connected to each other;

- the planet carrier of the first planetary gear set and the planet carrier of the second planetary gear set are operatively connected to each other;

- the sun gear of the third planetary gear set and the sun gear of the first planetary gear set are operatively connected to each other;

- the sun gear of the second planetary gear set and the ring gear of the fourth

planetary gear set are operatively connected to each other;

- the planet carrier of the first planetary gear set and the planet carrier of the second planetary gear set are selectively connectable to the ring gear of the third planetary gear set;

- the planet carrier of the first planetary gear set and the planet carrier of the second planetary gear set are selectively connectable to the planet carrier of the third planetary gear set;

- the sun gear of the fourth planetary gear set is selectively connectable to the ring gear of the third planetary gear set;

- the sun gear of the third planetary gear set and the sun gear of the first planetary gear set are selectively lockable to the transmission housing;

- the sun gear of the second planetary gear set and the ring gear of the fourth

planetary gear set are selectively lockable to the transmission housing;

- the ring gear of the second planetary gear set is selectively lockable to the

transmission housing;

- the sun gear of the fourth planetary gear set is operatively connected to the first transmission shaft, and

- the planet carrier of the third planetary gear set is operatively connected to the second transmission shaft.

A transmission assembly according to the present disclosure implies that a plurality of gears, such as ten gears in one direction and four gears in the opposite direction, may be obtained by using only four planetary gear sets and only a few, e.g. six, shift mechanisms, i.e. connecting or locking mechanisms. The above discussed set of gears may be obtainable for a transmission assembly in which each one of the planetary gear sets has a negative stationary gear ratio. Moreover, by virtue of the configuration of the transmission assembly according to the present disclosure, it is possible to obtain appropriate ratios and steps for at least a plurality of the gears of the transmission assembly.

DEFINITIONS

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

wherein o)_s is the speed of rotation of the sun gear;

ω_Ρ is the speed of rotation of the planet carrier;

o)_R 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" f? 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.:

R = - - for single planet gear wheels

and

for double planet gear wheels 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 vein, as used herein, the expression "ratio" for a transmission assembly relates to the number of revolutions of the transmission input shaft of the transmission assembly divided by the number of revolutions of the transmission output shaft of the transmission assembly. Moreover, as used herein, the expression "step" relates to the quotient of the ratio of a gear divided by the ratio of an adjacent gear of a transmission assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

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

Fig. 1 illustrates a vehicle, and

Fig. 2 schematically illustrates a transmission assembly according to an embodiment of the present disclosure.

It should be noted that the appended drawings are not necessarily drawn to scale and that the dimensions of some features of the present invention may have been exaggerated for the sake of clarity.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention will below be described for a vehicle in the form of an articulated hauler 1 such as the one illustrated in Fig. 1. The articulated hauler 1 should be seen as an example of a vehicle which could comprise a transmission assembly according to the present invention. However, the transmission assembly of the present invention may be implemented in a plurality of different types of objects, e.g. other types of vehicles. Purely by way of example, the transmission assembly could be implemented in a truck, a lorry, a tractor, a car, a bus, a working machine such as a wheel loader or an articulated hauler or any other type of construction equipment.

Fig. 2 illustrates an embodiment of a transmission assembly 10. The Fig. 2 embodiment of the transmission assembly 10 comprises a first 2, a second 14, a third 16 and a fourth 8 planetary gear set. Each one of the planetary gear sets comprises a ring gear R, a planet carrier P and a sun gear S. The transmission assembly further comprises a transmission housing 20 and a first 22 and a second 24 transmission shaft. The transmission housing 20 is only schematically depicted in Fig. 2 but the transmission housing 20 is generally adapted to enclose at least a portion of the planetary gear sets.

In the Fig. 2 embodiment of the transmission assembly 10, the planetary gear sets are arranged in the transmission housing 20 in the following order: the second 14, the fourth 18, the third 16 and the first 12 planetary gear set. The order illustrated in Fig. 2 implies that a relatively compact transmission assembly 10 may be obtained.

The transmission assembly 10 illustrated in Fig. 2 is configured according to the following.

The planet carrier 18P of the fourth planetary gear set 18 and the ring gear 2R of the first planetary gear set 12 are operatively connected to each other, for instance via a first connector 26.

The planet carrier 12P of the first planetary gear set 2 and the planet carrier 14P of the second planetary gear set 14 are operatively connected to each other, for instance via a second connector 28.

The sun gear 16S of the third planetary gear set 16 and the sun gear 12S of the first planetary gear set 12 are operatively connected to each other, for instance via a third connector 30.

The sun gear 14S of the second planetary gear set 14 and the ring gear 18R of the fourth planetary gear set 18 are operatively connected to each other, for instance via a fourth connector 32. The planet carrier 12P of the first planetary gear set 12 and the planet carrier 14P of the second planetary gear set 14 are selectively connectable to the ring gear 16R of the third planetary gear set 16. The planet carrier 12P of the first planetary gear set 12 and the planet carrier 1 P of the second planetary gear set 14 are selectively connectable to the planet carrier 16P of the third planetary gear set 16. The sun gear 18S of the fourth planetary gear set 18 is selectively connectable to the ring gear 16R of the third planetary gear set 16.

The sun gear 16S of the third planetary gear set 16 and the sun gear 12S of the first planetary gear set 12 are selectively lockable to the transmission housing 20.

The sun gear 14S of the second planetary gear set 14 and the ring gear 18R of the fourth planetary gear set 18 are selectively lockable to the transmission housing 20.

The ring gear 14R of the second planetary gear set 14 is selectively lockable to the transmission housing 20.

The sun gear 18S of the fourth planetary gear set 18 is operatively connected to the first transmission shaft 22. Purely by way of example, the first transmission shaft 22 may be a transmission input shaft.

The planet carrier 16P of the third planetary gear set 16 is operatively connected to the second transmission shaft 24. Purely by way of example, the second transmission shaft 24 may be a transmission output shaft. Purely by way of example, each one of the above discussed connectors 26, 28, 30, 32 may comprise a shaft. As a non-limiting example, one or more of the connectors 26, 28, 30, 32 may comprise a hollow shaft. For instance, such a hollow shaft may accommodate another member, e.g. another shaft and/or another connector 26, 28, 30, 32. Purely by way of example, the stationary gear ratio of each one of the first 12, second 14, third 16 and fourth 18 planetary gear sets is negative.

As a non-limiting example, the stationary gear ratios of the planetary gear sets may be within the ranges that are presented in Table 1 hereinbelow. Table 1 - Stationary gear ratio ranges

Purely by way of example, the stationary gear ratios of the planetary gear sets may be selected in accordance with the values presented in Table 2.

Table 2 - Stationary gear ratios

The Fig. 2 embodiment of the transmission assembly 10 further comprises a

gear selection arrangement 36 that enables selection of different operating modes with different gear ratios.

The implementation of the gear selection arrangement 36 illustrated in Fig. 2 comprises shift mechanisms that are presented hereinbelow.

The gear selection arrangement 36 comprises a first connecting mechanism 38 that is adapted to assume an engaged condition in which the sun gear 18S of the fourth planetary gear set 18 is operatively connected to the ring gear 16R of the third planetary gear set 16. Moreover, the first connecting mechanism 38 is also adapted to assume a disengaged condition in which the sun gear 18S of the fourth planetary gear set 18 is not operatively connected to the ring gear 16R of the third planetary gear set 16.

Additionally, the gear selection arrangement 36 comprises a second connecting mechanism 40 that is adapted to assume an engaged condition in which the planet carrier 12P of the first planetary gear set 12 and the planet carrier 14P of the second planetary gear set 14 are operatively connected to the planet carrier 16P of the third planetary gear set 16. Moreover, the second connecting mechanism 40 is adapted to assume a disengaged condition in which the planet carrier 12P of the first planetary gear set 12 and the planet carrier 14P of the second planetary gear set 14 are not operatively connected to the planet carrier 16P of the third planetary gear set 16. Further, the gear selection arrangement 36 comprises a third connecting mechanism 42 adapted to assume an engaged condition in which the planet carrier 12P of the first planetary gear set 12 and the planet carrier 14P of the second planetary gear set 14 are 5 operatively connected to the ring gear 16R of the third planetary gear set 16. Moreover, the third connecting mechanism 42 is adapted to assume a disengaged condition in which the planet carrier 12P of the first planetary gear set 12 and the planet carrier 14P of the second planetary gear set 14 are not operatively connected to the ring gear 16R of the third planetary gear set 16.

10

Purely by way of example, each one of the first, second and third connecting mechanisms 38, 40, 42 may comprise a clutch, such as a friction clutch, a dog clutch or a one-way clutch.

15 Moreover, the gear selection arrangement 36 comprises a first locking mechanism 44 adapted to assume an engaged condition in which the sun gear 16S of the third planetary gear set 16 and the sun gear 12S of the first planetary gear set 12 are locked to the transmission housing 20. Further, the first locking mechanism 44 is adapted to assume a disengaged condition in which the sun gear 16S of the third planetary gear set 16 and the

20 sun gear 12S of the first planetary gear set 12 are not locked to the transmission housing 20. Purely by way of example, the third connector 30 that has been discussed

hereinabove may be connectable to the first locking mechanism 44.

Furthermore, the gear selection arrangement 36 comprises a second locking mechanism 25 46 adapted to assume an engaged condition in which the ring gear 14R of the second planetary gear set 14 is locked to the transmission housing 20. The second locking mechanism 46 is also adapted to assume a disengaged condition in which the ring gear 14R of the second planetary gear set 14 is not locked to the transmission housing 20.

30 Moreover, the gear selection arrangement 36 comprises a third locking mechanism 48 adapted to assume an engaged condition in which the sun gear 14S of the second planetary gear set 14 and the ring gear 18R of the fourth planetary gear set 18 are locked to the transmission housing 20. The third locking mechanism 48 is also adapted to assume a disengaged condition in which the sun gear 14S of the second planetary gear

35 set 14 and the ring gear 18R of the fourth planetary gear set 18 are not locked to the transmission housing 20. Purely by way of example, the fourth connector 32 that has been discussed hereinabove may be connectable to the third locking mechanism 48.

Purely by way of example, each one of the first, second and third locking mechanisms 44, 46, 48 may comprise a brake, such as a friction brake, a dog clutch type brake or a oneway clutch type brake.

The above discussed implementation of the gear selection arrangement 36 is adapted to assume the gears as presented in Table 3 with absolute values of gear ratios in descending order. Moreover, the gear selection arrangement 36 may also be adapted to assume the gears as presented in Table 4 with absolute values of gear ratios in descending order. The gears as presented in Table 4 are in the opposite driving direction as compared to the driving direction of the gears presented in Table 3. In each one of Table 3 and Table 4, a cell marked with an x indicates an engaged condition whereas a blank cell indicates a disengaged condition. Moreover, each one of Table 3 and Table 4 presents the gear ratios and steps obtainable if the planetary gear sets have the stationary gear ratios that are presented in Table 2. Furthermore, Table 3 as well as Table 4 presents values for a transmission assembly 10 in which the first transmission shaft 22 is a transmission input shaft and the second transmission shaft 24 is a transmission output shaft.

Table 3 - Gears obtainable b the Fi . 2 ear selection arran ement 36

Table 4 - Gears obtainable by the Fig. 2 gear selection arrangement 36

Finally, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

Claims

1. A transmission assembly (10) comprising a first (12), a second (14), a third (16) and a fourth (18) planetary gear set, each one of said planetary gear sets (12, 14, 16, 8) comprising a ring gear, a planet carrier and a sun gear, said transmission assembly (10) further comprising a transmission housing (20) and a first (22) and a second (24) transmission shaft, said transmission assembly (10) being configured such that:

- said planet carrier (18P) of said fourth planetary gear set (18) and said ring gear (12R) of said first planetary gear set (12) are operatively connected to each other;

- said planet carrier (12P) of said first planetary gear set (12) and said planet carrier (14P) of said second planetary gear set (14) are operatively connected to each other;

- said sun gear (16S) of said third planetary gear set (16) and said sun gear (12S) of said first planetary gear set (12) are operatively connected to each other;

- said sun gear (14S) of said second planetary gear set (14) and said ring gear (18R) of said fourth planetary gear set (18) are operatively connected to each other;

- said planet carrier (12P) of said first planetary gear set (12) and said planet carrier (14P) of said second planetary gear set (14) are selectively connectable to said ring gear (16R) of said third planetary gear set (16);

- said planet carrier (12P) of said first planetary gear set (12) and said planet carrier (14P) of said second planetary gear set (14) are selectively connectable to said planet carrier (16P) of said third planetary gear set (16);

- said sun gear (18S) of said fourth planetary gear set (18) is selectively connectable to said ring gear (16R) of said third planetary gear set (16);

- said sun gear (16S) of said third planetary gear set (16) and said sun gear (12S) of said first planetary gear set (12) are selectively lockable to said transmission housing (20); - said sun gear (14S) of said second planetary gear set (14) and said ring gear (18R) of said fourth planetary gear set (18) are selectively lockable to said transmission housing (20);

- said ring gear (14R) of said second planetary gear set (14) is selectively lockable to said transmission housing (20);

- said sun gear (18S) of said fourth planetary gear set (18) is operatively connected to said first transmission shaft (22), and

- said planet carrier (16P) of said third planetary gear set (16) is operatively connected to said second transmission shaft (24).

The transmission assembly (10) according to claim 1 , wherein the stationary gear ratio of each one of said first, second, third and fourth planetary gear set (12, 14, 16, 18) is negative.

The transmission assembly (10) according to any one of the preceding claims, wherein said planetary gear sets are arranged in said transmission housing (20) in the following order: said second (14), said fourth (18), said third (16) and said first (12) planetary gear set.

The transmission assembly (10) according to any one of the preceding claims, wherein said first transmission shaft (22) is a transmission input shaft and said second transmission shaft (24) is a transmission output shaft.

5. The transmission assembly (10) according to any one of the preceding claims, wherein said transmission assembly (10) comprises a gear selection arrangement (36) that enables selection of different operating modes with different gear ratios, said gear selection arrangement (36) comprising:

- a first connecting mechanism (38), said first connecting mechanism (38) being adapted to assume an engaged condition in which said sun gear (18S) of said fourth planetary gear set ( 8) is operatively connected to said ring gear (16R) of said third planetary gear set (16), said first connecting mechanism (38) also being adapted to assume a disengaged condition in which said sun gear (18S) of said fourth planetary gear set (18) is not operatively connected to said ring gear (16R) of said third planetary gear set (16); a second connecting mechanism (40), said second connecting mechanism (40), being adapted to assume an engaged condition in which said planet carrier (12P) of said first planetary gear set (12) and said planet carrier (14P) of said second planetary gear set (14) are operatively connected to said planet carrier (16P) of said third planetary gear set (16), said second connecting mechanism (40) also being adapted to assume a disengaged condition in which said planet carrier (12P) of said first planetary gear set (12) and said planet carrier (14P) of said second planetary gear set (14) are not operatively connected to said planet carrier (16P) of said third planetary gear set (16);

a third connecting mechanism (42), said third connecting mechanism (42) being adapted to assume an engaged condition in which said planet carrier (12P) of said first planetary gear set (12) and said planet carrier (14P) of said second planetary gear set (14) are operatively connected to said ring gear (16R) of said third planetary gear set (16), said third connecting mechanism (42) also being adapted to assume a disengaged condition in which said planet carrier (12P) of said first planetary gear set (12) and said planet carrier (14P) of said second planetary gear set (14) are not operatively connected to said ring gear (16R) of said third planetary gear set (16);

a first locking mechanism (44) adapted to assume an engaged condition in which said sun gear (16S) of said third planetary gear set (16) and said sun gear (12S) of said first planetary gear set (12) are locked to said transmission housing (20), said first locking mechanism (44) being adapted to assume a disengaged condition in which said sun gear (16S) of said third planetary gear set (16) and said sun gear (12S) of said first planetary gear set (12) are not locked to said transmission housing (20);

a second locking mechanism (46) adapted to assume an engaged condition in which said ring gear (14R) of said second planetary gear set (14) is locked to said transmission housing (20), said second locking mechanism (46) being adapted to assume a disengaged condition in which said ring gear (14R) of said second planetary gear set (14) is not locked to said transmission housing (20), and

a third locking mechanism (48) adapted to assume an engaged condition in which said sun gear (14S) of said second planetary gear set (14) and said ring gear (18R) of said fourth planetary gear set (18) are locked to said transmission housing (20), said third locking mechanism (48) being adapted to assume a disengaged condition in which said sun gear (14S) of said second planetary gear set (14) and said ring gear (18R) of said fourth planetary gear set (18) are not locked to said transmission housing (20).

6. The transmission assembly (10) according to claim 5, wherein said gear selection arrangement (36) is adapted to assume the following gears with absolute values of gear ratios in descending order:

The transmission assembly ( 0) according to claim 6, wherein said gear selection arrangement (36) is adapted to assume the following gears, in the opposite driving direction as compared to the driving direction of the gears of claim 6, with absolute values of gear ratios in descending order:

8. A working machine (1) comprising a transmission assembly (10) according to any one of the preceding claims.