Multi-speed transmission

Abstract

The present invention reduces variations in step ratio. First to fourth planetary gear sets (1‒4) are arranged in an axial direction in order from an input member (7) toward an output member (10), and each gear set includes a sun gear, a planetary carrier, and a ring gear. First to fourth clutches (51‒54) and first and second brakes (61, 62) are each operably connected to at least one planetary gear set among the planetary gear sets (1‒4), and are capable of selectively engaging with the gear sets so as to create a set of different gear ratios including at least ten forward gear ratios and at least one reverse gear ratio between the input member (7) and the output member (10). The first clutch (51) selectively connects a first planetary carrier (14) and a fourth ring gear (43).

Description

Multi-speed transmission

[0001] The present disclosure relates to a multi-speed transmission.

[0002] Work vehicles such as dump trucks are equipped with multi-speed transmissions that have multiple planetary gear sets. Planetary gear multi-speed transmissions can obtain a desired reduction ratio by appropriately combining and using the rotating elements of each planetary gear set. A conventional multi-speed transmission that includes four planetary gear sets and six control elements and is capable of generating ten forward speeds and one reverse speed is disclosed, for example, in U.S. Pat. No. 1,006,0511 (Patent Document 1).

[0003] U.S. Pat. No. 1,006,0511

[0004] In a multi-speed transmission, there is a demand for a reduction in the variation in the gear ratio in order to smoothly switch between gear stages.

[0005] The present disclosure proposes a multi-speed transmission that can reduce variations in inter-speed ratios.

[0006] A multi-speed transmission according to one aspect of the present disclosure includes an input member and an output member. The multi-speed transmission includes four or less planetary gear sets. The four or less planetary gear sets include a first planetary gear set, a second planetary gear set, a third planetary gear set, and a fourth planetary gear set, arranged axially in that order from the input member to the output member. Each planetary gear set includes a plurality of rotating elements. The plurality of rotating elements includes a sun gear, a planet carrier, and a ring gear. The multi-speed transmission includes six or less control elements. Each of the six or less control elements is operably coupled to at least one planetary gear set of the four or less planetary gear sets and is selectively engageable to generate a set of different gear ratios between the input member and the output member. The set of different gear ratios includes at least ten forward gear ratios and at least one reverse gear ratio. One of the six or fewer control elements selectively couples the planet carrier of the first planetary gear set to the ring gear of the fourth planetary gear set.

[0007] A multi-speed transmission according to one aspect of the present disclosure includes an input member and an output member. The multi-speed transmission includes four or less planetary gear sets. The four or less planetary gear sets include a first planetary gear set, a second planetary gear set, a third planetary gear set, and a fourth planetary gear set, arranged axially in that order from the input member to the output member. Each planetary gear set includes a plurality of rotating elements. The plurality of rotating elements includes a sun gear, a planet carrier, and a ring gear. The multi-speed transmission includes six or less control elements. Each of the six or less control elements is operably coupled to at least one planetary gear set of the four or less planetary gear sets and is selectively engageable to generate a set of different gear ratios between the input member and the output member. The set of different gear ratios includes at least ten forward gear ratios and at least one reverse gear ratio. One of the six or fewer control elements selectively couples the sun gear of the second planetary gear set to the sun gear of the third planetary gear set.

[0008] According to the multi-speed transmission of the present disclosure, it is possible to reduce the variation in the gear ratio.

[0009] FIG. 1 is a schematic diagram of a multi-speed transmission according to a first embodiment. FIG. 2 is a table showing each clutch or brake that is engaged at each speed stage of the multi-speed transmission according to the first embodiment. FIG. 3 is a table showing the gear ratios of each planetary gear set of the multi-speed transmission according to the first embodiment. FIG. 4 is a table showing each clutch or brake that is engaged at each speed stage of the multi-speed transmission according to a second embodiment. FIG. 5 is a table showing the gear ratios of each planetary gear set of the multi-speed transmission according to the second embodiment. FIG. 6 is a schematic diagram of a multi-speed transmission according to a third embodiment. FIG. 7 is a table showing each clutch or brake that is engaged at each speed stage of the multi-speed transmission according to the third embodiment. FIG. 8 is a table showing the gear ratios of each planetary gear set of the multi-speed transmission according to the third embodiment.

[0010] Hereinafter, various embodiments of the multi-speed transmission 100 will be described with reference to the drawings. In the various embodiments described below, the same or corresponding parts will be denoted by the same reference numerals, and overlapping descriptions may not be repeated.

[0011] 1 is a schematic diagram of a multi-speed transmission 100 according to a first embodiment. The multi-speed transmission 100 changes the rotational speed of power input from an arbitrary drive source (not shown), such as an internal combustion engine represented by a diesel engine, an electric motor, or the like, and outputs the power. The power from the drive source may be input to the multi-speed transmission 100 via a torque converter.

[0012] The multi-speed transmission 100 includes a plurality of planetary gear sets 1 to 4, a plurality of clutches 51 to 54, a plurality of brakes 61 to 62, an input member 7, a first intermediate coupling member 81, a second intermediate coupling member 82, a third intermediate coupling member 83, a fourth intermediate coupling member 84, an output member 10, and a housing 9. The planetary gear sets 1 to 4, the clutches 51 to 54, the brakes 61 to 62, the input member 7, the first intermediate coupling member 81, the second intermediate coupling member 82, the third intermediate coupling member 83, the fourth intermediate coupling member 84, and the output member 10 are accommodated in the housing 9.

[0013] In the following description, the rotation axis O refers to the center line of the input member 7 and the output member 10. The rotation axis direction refers to the direction in which the rotation axis O extends. The radial direction refers to the radial direction of a circle centered on the rotation axis O. In FIG. 1 and subsequent FIG. 6, the left-right direction in the figure refers to the rotation axis direction, and the up-down direction in the figure refers to the radial direction. The input side refers to the side from which the multi-speed transmission 100 inputs power. The output side refers to the side from which the multi-speed transmission 100 outputs power. In FIG. 1 and subsequent FIG. 6, the left side in the figure is the input side, and the right side in the figure is the output side.

[0014] The multiple planetary gear sets include a first planetary gear set 1, a second planetary gear set 2, a third planetary gear set 3, and a fourth planetary gear set 4. The multiple clutches include a first clutch 51, a second clutch 52, a third clutch 53, and a fourth clutch 54. The multiple brakes include a first brake 61 and a second brake 62. Each of the clutches 51 to 54 and each of the brakes 61 to 62 corresponds to a control element in the embodiment. The six control elements include the first clutch 51, the second clutch 52, the third clutch 53, the fourth clutch 54, the first brake 61, and the second brake 62.

[0015] The first planetary gear set 1, the second planetary gear set 2, the third planetary gear set 3, and the fourth planetary gear set 4 are supported rotatably about a rotation axis O. The first planetary gear set 1, the second planetary gear set 2, the third planetary gear set 3, and the fourth planetary gear set 4 are arranged in this order along the rotation axis direction. More specifically, the first planetary gear set 1, the second planetary gear set 2, the third planetary gear set 3, and the fourth planetary gear set 4 are arranged in this order from the input side to the output side.

[0016] The input member 7 is configured to rotate about a rotation axis O. Power is input to the input member 7 from a drive source such as an engine.

[0017] The first intermediate coupling member 81 is configured to rotate around a rotation axis O. The first intermediate coupling member 81 has a portion extending in the direction of the rotation axis O. The rotation center of the first intermediate coupling member 81 and the center line of the input member 7 are substantially the same.

[0018] The second intermediate coupling member 82 is configured to rotate around a rotation axis O. The second intermediate coupling member 82 has a portion extending in the direction of the rotation axis O. The rotation center of the second intermediate coupling member 82 and the center line of the input member 7 are substantially the same.

[0019] The third intermediate connecting member 83 is configured to rotate around the rotation axis O. The third intermediate connecting member 83 has a portion extending in the direction of the rotation axis O. The rotation center of the third intermediate connecting member 83 and the center line of the input member 7 are substantially the same.

[0020] The fourth intermediate coupling member 84 is configured to rotate around the rotation axis O. The fourth intermediate coupling member 84 has a portion extending in the direction of the rotation axis O. The rotation center of the fourth intermediate coupling member 84 and the center line of the input member 7 are substantially the same.

[0021] The first planetary gear set 1 is a single-pinion planetary gear mechanism and includes a plurality of rotating elements, such as a first sun gear 11, a plurality of first planetary gears 12, a first ring gear 13, and a first planetary carrier 14.

[0022] The first sun gear 11 is disposed rotatably about the rotation axis O. The first sun gear 11 is disposed radially outward of the second intermediate connecting member 82. More specifically, the first sun gear 11 is annular, and the second intermediate connecting member 82 passes through the first sun gear 11. The second intermediate connecting member 82 and the input member 7 are rotatable relative to each other.

[0023] The first sun gear 11 is configured to rotate integrally with the first intermediate connecting member 81. More specifically, the first sun gear 11 is fixed to the first intermediate connecting member 81. The first sun gear 11 and the first intermediate connecting member 81 may be formed by a single member.

[0024] Each first planetary gear 12 is configured to mesh with the first sun gear 11. Each first planetary gear 12 is disposed radially outward of the first sun gear 11. Specifically, each first planetary gear 12 is disposed at intervals in the circumferential direction.

[0025] Each first planetary gear 12 is configured to revolve around the first sun gear 11. Each first planetary gear 12 is configured to rotate around a rotation axis O. Furthermore, each first planetary gear 12 is configured to rotate on its own axis.

[0026] The first ring gear 13 is in mesh with each of the first planetary gears 12. The first ring gear 13 is configured to rotate about a rotation axis O.

[0027] The first ring gear 13 is configured to rotate integrally with the input member 7. More specifically, the first ring gear 13 is fixed to the input member 7. The input member 7 is connected to a rotating element of the first planetary gear set 1. The first ring gear 13 and the input member 7 may be formed by a single member.

[0028] The first planetary carrier 14 supports each of the first planetary gears 12. Each of the first planetary gears 12 is rotatable while being supported by the first planetary carrier 14. The first planetary carrier 14 is configured to rotate about a rotation axis O.

[0029] The first planetary carrier 14 is configured to rotate integrally with the second intermediate coupling member 82. More specifically, the first planetary carrier 14 is fixed to the second intermediate coupling member 82. The first planetary carrier 14 and the second intermediate coupling member 82 may be formed by a single member.

[0030] The second planetary gear set 2 is a single-pinion planetary gear mechanism and includes a plurality of rotating elements, such as a second sun gear 21, a plurality of second planetary gears 22, a second ring gear 23, and a second planetary carrier 24.

[0031] The second sun gear 21 is configured to be rotatable about the rotation axis O. The second sun gear 21 is configured to rotate integrally with the second intermediate connecting member 82. More specifically, the second sun gear 21 is fixed to the second intermediate connecting member 82. The second sun gear 21 and the second intermediate connecting member 82 may be formed as a single member. The second intermediate connecting member 82 connects the first planetary carrier 14 of the first planetary gear set 1 and the second sun gear 21 of the second planetary gear set 2. The first planetary carrier 14 and the second sun gear 21 are configured to rotate integrally with each other.

[0032] Each second planetary gear 22 is configured to mesh with the second sun gear 21. Each second planetary gear 22 is disposed radially outward of the second sun gear 21. Specifically, each second planetary gear 22 is disposed at intervals in the circumferential direction.

[0033] Each second planetary gear 22 is configured to revolve around the second sun gear 21. Each second planetary gear 22 is configured to rotate around a rotation axis O. Furthermore, each second planetary gear 22 is configured to rotate on its own axis.

[0034] The second ring gear 23 is in mesh with each of the second planetary gears 22. The second ring gear 23 is configured to rotate about a rotation axis O.

[0035] The second ring gear 23 is configured to rotate integrally with the first intermediate connecting member 81. More specifically, the second ring gear 23 is fixed to the first intermediate connecting member 81. The second ring gear 23 and the first intermediate connecting member 81 may be formed as a single member. The first intermediate connecting member 81 connects the first sun gear 11 of the first planetary gear set 1 and the second ring gear 23 of the second planetary gear set 2. The first sun gear 11 and the second ring gear 23 are configured to rotate integrally with each other.

[0036] The second planetary carrier 24 supports each of the second planetary gears 22. Each of the second planetary gears 22 is rotatable while being supported by the second planetary carrier 24. The second planetary carrier 24 is configured to rotate about a rotation axis O.

[0037] The second planetary carrier 24 is configured to rotate integrally with the third intermediate coupling member 83. More specifically, the second planetary carrier 24 is fixed to the third intermediate coupling member 83. The second planetary carrier 24 and the third intermediate coupling member 83 may be formed by a single member.

[0038] The third planetary gear set 3 is a single-pinion planetary gear mechanism and includes a plurality of rotating elements, such as a third sun gear 31, a plurality of third planetary gears 32, a third ring gear 33, and a third planetary carrier 34.

[0039] The third sun gear 31 is disposed rotatably about the rotation axis O. The third sun gear 31 is configured to rotate integrally with the fourth intermediate connecting member 84. More specifically, the third sun gear 31 is fixed to the fourth intermediate connecting member 84. The third sun gear 31 and the fourth intermediate connecting member 84 may be formed by a single member.

[0040] Each third planetary gear 32 is configured to mesh with the third sun gear 31. Each third planetary gear 32 is disposed radially outward of the third sun gear 31. Specifically, each third planetary gear 32 is disposed at intervals in the circumferential direction.

[0041] Each third planetary gear 32 is configured to revolve around the third sun gear 31. Each third planetary gear 32 is configured to rotate around a rotation axis O. Furthermore, each third planetary gear 32 is configured to rotate on its own axis.

[0042] The third ring gear 33 is in mesh with each of the third planetary gears 32. The third ring gear 33 is configured to rotate about a rotation axis O.

[0043] The third ring gear 33 is configured to rotate integrally with the third intermediate connecting member 83. More specifically, the third ring gear 33 is fixed to the third intermediate connecting member 83. The third ring gear 33 and the third intermediate connecting member 83 may be formed as a single member. The third intermediate connecting member 83 connects the second planetary carrier 24 of the second planetary gear set 2 and the third ring gear 33 of the third planetary gear set 3. The second planetary carrier 24 and the third ring gear 33 are configured to rotate integrally with each other.

[0044] The third planetary carrier 34 supports each of the third planetary gears 32. Each of the third planetary gears 32 is rotatable while being supported by the third planetary carrier 34. The third planetary carrier 34 is configured to rotate about a rotation axis O.

[0045] The fourth planetary gear set 4 is a single-pinion planetary gear mechanism and includes a plurality of rotating elements, such as a fourth sun gear 41, a plurality of fourth planetary gears 42, a fourth ring gear 43, and a fourth planetary carrier 44.

[0046] The fourth sun gear 41 is arranged to be rotatable about the rotation axis O. The fourth sun gear 41 is arranged radially outward of the output member 10. More specifically, the fourth sun gear 41 is annular, and the output member 10 passes through the fourth sun gear 41. The fourth sun gear 41 and the output member 10 are rotatable relative to each other.

[0047] Each fourth planetary gear 42 is configured to mesh with the fourth sun gear 41. Each fourth planetary gear 42 is disposed radially outward of the fourth sun gear 41. Specifically, each fourth planetary gear 42 is disposed at intervals in the circumferential direction.

[0048] Each fourth planetary gear 42 is configured to revolve around the fourth sun gear 41. Each fourth planetary gear 42 is configured to rotate about a rotation axis O. Furthermore, each fourth planetary gear 42 is configured to rotate on its own axis.

[0049] The fourth ring gear 43 is in mesh with each of the fourth planetary gears 42. The fourth ring gear 43 is configured to rotate about a rotation axis O.

[0050] The fourth ring gear 43 is configured to rotate integrally with the fourth intermediate connecting member 84. More specifically, the fourth ring gear 43 is fixed to the fourth intermediate connecting member 84. The fourth ring gear 43 and the fourth intermediate connecting member 84 may be formed as a single member. The fourth intermediate connecting member 84 connects the third sun gear 31 of the third planetary gear set 3 and the fourth ring gear 43 of the fourth planetary gear set 4. The third sun gear 31 and the fourth ring gear 43 are configured to rotate integrally with each other.

[0051] The fourth planetary carrier 44 supports each of the fourth planetary gears 42. Each of the fourth planetary gears 42 is rotatable while being supported by the fourth planetary carrier 44. The fourth planetary carrier 44 is configured to rotate about a rotation axis O.

[0052] The fourth planetary carrier 44 is configured to rotate integrally with the output member 10. The fourth planetary carrier 44 is fixed to the output member 10. The output member 10 is connected to the rotating elements of the fourth planetary gear set 4. The fourth planetary carrier 44 and the output member 10 may be formed by a single member. The output member 10 outputs power. Specifically, the output member 10 outputs power having a rotational speed changed by the multi-speed transmission 100.

[0053] First clutch 51 is configured to selectively connect second intermediate connecting member 82 and fourth intermediate connecting member 84. First clutch 51 is configured to selectively connect first planetary carrier 14 and second sun gear 21, and third sun gear 31 and fourth ring gear 43. First clutch 51 is, for example, a hydraulic clutch mechanism and can be composed of a plurality of discs.

[0054] When engaged, the first clutch 51 connects the second intermediate connecting member 82 and the fourth intermediate connecting member 84. When engaged, the first clutch 51 connects the first planetary carrier 14 and the second sun gear 21 to the third sun gear 31 and the fourth ring gear 43 via the second intermediate connecting member 82 and the fourth intermediate connecting member 84. Therefore, when the first clutch 51 is engaged, the first planetary carrier 14, the second sun gear 21, the third sun gear 31, and the fourth ring gear 43 rotate integrally. When disengaged, the first clutch 51 releases the connection between the second intermediate connecting member 82 and the fourth intermediate connecting member 84. Therefore, when the first clutch 51 is disengaged, the first planetary carrier 14 and the second sun gear 21 are rotatable relative to the third sun gear 31 and the fourth ring gear 43.

[0055] The second clutch 52 is configured to selectively connect the second intermediate connecting member 82 to the third planetary carrier 34. The second clutch 52 is configured to selectively connect the first planetary carrier 14 and the second sun gear 21 to the third planetary carrier 34. The second clutch 52 is, for example, a hydraulic clutch mechanism and can be composed of a plurality of discs.

[0056] When engaged, the second clutch 52 connects the second intermediate connecting member 82 to the third planetary carrier 34. When engaged, the second clutch 52 connects the first planetary carrier 14 and the second sun gear 21 to the third planetary carrier 34 via the second intermediate connecting member 82. Therefore, when the second clutch 52 is engaged, the first planetary carrier 14, the second sun gear 21, and the third planetary carrier 34 rotate integrally. When disengaged, the second clutch 52 releases the connection between the second intermediate connecting member 82 and the third planetary carrier 34. Therefore, when the second clutch 52 is disengaged, the first planetary carrier 14 and the second sun gear 21 are rotatable relative to the third planetary carrier 34.

[0057] The third clutch 53 is configured to selectively connect the third planetary carrier 34 and the fourth sun gear 41. The third clutch 53 is, for example, a hydraulic clutch mechanism and can be configured with a plurality of discs.

[0058] When engaged, the third clutch 53 connects the third planetary carrier 34 and the fourth sun gear 41. Therefore, when the third clutch 53 is engaged, the third planetary carrier 34 and the fourth sun gear 41 rotate integrally. When disengaged, the third clutch 53 releases the connection between the third planetary carrier 34 and the fourth sun gear 41. Therefore, when the third clutch 53 is disengaged, the third planetary carrier 34 and the fourth sun gear 41 can rotate relative to each other.

[0059] The fourth clutch 54 is configured to selectively connect the third planetary carrier 34 and the fourth planetary carrier 44. The fourth clutch 54 is, for example, a hydraulic clutch mechanism and can be configured with a plurality of discs.

[0060] When the fourth clutch 54 is engaged, it connects the third planetary carrier 34 and the fourth planetary carrier 44 together. Therefore, when the fourth clutch 54 is engaged, the third planetary carrier 34, the fourth planetary carrier 44, and the output member 10 rotate integrally. When the fourth clutch 54 is disengaged, it releases the connection between the third planetary carrier 34 and the fourth planetary carrier 44. Therefore, when the fourth clutch 54 is disengaged, the third planetary carrier 34 is rotatable relative to the fourth planetary carrier 44 and the output member 10.

[0061] The first brake 61 is configured to selectively connect the first intermediate connecting member 81 and the housing 9 .

[0062] When in an engaged state, first brake 61 connects first intermediate coupling member 81 to housing 9. When in an engaged state, first brake 61 brakes the rotation of first sun gear 11 and second ring gear 23 via first intermediate coupling member 81, and first sun gear 11 and second ring gear 23 are unable to rotate. When in a released state, first brake 61 releases the connection between first intermediate coupling member 81 and housing 9. When in a released state, first brake 61 does not brake the rotation of first sun gear 11 and second ring gear 23, and first sun gear 11 and second ring gear 23 are able to rotate.

[0063] The second brake 62 is configured to selectively connect the fourth sun gear 41 and the housing 9 together.

[0064] When engaged, second brake 62 connects fourth sun gear 41 to housing 9. When engaged, second brake 62 brakes the rotation of fourth sun gear 41, preventing the rotation of fourth sun gear 41. When released, second brake 62 releases the connection between fourth sun gear 41 and housing 9. When released, second brake 62 does not brake the rotation of fourth sun gear 41, allowing the fourth sun gear 41 to rotate.

[0065] In the multi-speed transmission 100 configured as described above, each of the first to fourth clutches 51 to 54 and the first to second brakes 61 to 62 is operatively coupled to at least one of the first to fourth planetary gear sets 1 to 4. By selectively engaging the first to fourth clutches 51 to 54 and the first to second brakes 61 to 62 to restrict the rotation of the rotating elements of the first to fourth planetary gear sets 1 to 4, a set of different gear ratios is generated between the input member 7 and the output member 10. The set of different gear ratios includes at least ten forward gear ratios and one reverse gear ratio.

[0066] Fig. 2 is a table showing the clutches 51-54 or brakes 61-62 that are engaged at each speed stage of the multi-speed transmission 100. Fig. 2 illustrates the operating states of the first to fourth clutches 51-54 and first to second brakes 61-62 that correspond to each speed stage. An X in the column for the first to fourth clutches 51-54 and first to second brakes 61-62 indicates that they are engaged, and a blank column indicates that they are released (disengaged).

[0067] When the speed stage of the multi-speed transmission 100 is set to the first forward speed (F1), the third clutch 53, the fourth clutch 54, and the first brake 61 are engaged, and the first clutch 51, the second clutch 52, and the second brake 62 are disengaged. The engaged third clutch 53 connects the third planetary carrier 34 to the fourth sun gear 41. The engaged fourth clutch 54 connects the third planetary carrier 34 to the fourth planetary carrier 44 and the output member 10. The engaged first brake 61 brakes the rotation of the first sun gear 11 and the second ring gear 23.

[0068] When the speed stage of the multi-speed transmission 100 is set to the second forward speed (F2), the fourth clutch 54, the first brake 61, and the second brake 62 are engaged, and the first clutch 51, the second clutch 52, and the third clutch 53 are disengaged. The engaged fourth clutch 54 connects the third planetary carrier 34 with the fourth planetary carrier 44 and the output member 10. The engaged first brake 61 brakes the rotation of the first sun gear 11 and the second ring gear 23. The engaged second brake 62 brakes the rotation of the fourth sun gear 41.

[0069] When shifting the gear stage of multi-speed transmission 100 to third forward speed (F3), first clutch 51, fourth clutch 54, and first brake 61 are engaged, and second clutch 52, third clutch 53, and second brake 62 are disengaged. The engaged first clutch 51 couples first planetary carrier 14 and second sun gear 21 with third sun gear 31 and fourth ring gear 43. The engaged fourth clutch 54 couples third planetary carrier 34 with fourth planetary carrier 44 and output member 10. The engaged first brake 61 brakes the rotation of first sun gear 11 and second ring gear 23.

[0070] When shifting multi-speed transmission 100 to fourth forward speed (F4), first clutch 51, first brake 61, and second brake 62 are engaged, and second clutch 52, third clutch 53, and fourth clutch 54 are disengaged. The engaged first clutch 51 connects first planetary carrier 14 and second sun gear 21 with third sun gear 31 and fourth ring gear 43. The engaged first brake 61 brakes the rotation of first sun gear 11 and second ring gear 23. The engaged second brake 62 brakes the rotation of fourth sun gear 41.

[0071] When shifting the speed stage of multi-speed transmission 100 to fifth forward speed (F5), first clutch 51, fourth clutch 54, and second brake 62 are engaged, and second clutch 52, third clutch 53, and first brake 61 are disengaged. The engaged first clutch 51 couples first planetary carrier 14 and second sun gear 21 with third sun gear 31 and fourth ring gear 43. The engaged fourth clutch 54 couples third planetary carrier 34 with fourth planetary carrier 44 and output member 10. The engaged second brake 62 brakes the rotation of fourth sun gear 41.

[0072] When shifting the gear stage of multi-speed transmission 100 to sixth forward speed (F6), first clutch 51, second clutch 52, and second brake 62 are engaged, and third clutch 53, fourth clutch 54, and first brake 61 are disengaged. The engaged first clutch 51 connects first planetary carrier 14 and second sun gear 21 to third sun gear 31 and fourth ring gear 43. The engaged second clutch 52 connects first planetary carrier 14 and second sun gear 21 to third planetary carrier 34. The engaged second brake 62 brakes the rotation of fourth sun gear 41.

[0073] When shifting the speed stage of the multi-speed transmission 100 to the seventh forward speed (F7), the second clutch 52, the fourth clutch 54, and the second brake 62 are engaged, and the first clutch 51, the third clutch 53, and the first brake 61 are disengaged. The engaged second clutch 52 connects the first planetary carrier 14 and the second sun gear 21 to the third planetary carrier 34. The engaged fourth clutch 54 connects the third planetary carrier 34 to the fourth planetary carrier 44 and the output member 10. The engaged second brake 62 brakes the rotation of the fourth sun gear 41.

[0074] When the gear stage of the multi-speed transmission 100 is set to the eighth forward speed (F8), the second clutch 52, the third clutch 53, and the fourth clutch 54 are engaged, and the first clutch 51, the first brake 61, and the second brake 62 are disengaged. The engaged second clutch 52 connects the first planetary carrier 14 and the second sun gear 21 to the third planetary carrier 34. The engaged third clutch 53 connects the third planetary carrier 34 to the fourth sun gear 41. The engaged fourth clutch 54 connects the third planetary carrier 34 to the fourth planetary carrier 44 and the output member 10.

[0075] When shifting the gear stage of multi-speed transmission 100 to ninth forward speed (F9), second clutch 52, first brake 61, and second brake 62 are engaged, and first clutch 51, third clutch 53, and fourth clutch 54 are disengaged. The engaged second clutch 52 connects first planetary carrier 14 and second sun gear 21 with third planetary carrier 34. The engaged first brake 61 brakes the rotation of first sun gear 11 and second ring gear 23. The engaged second brake 62 brakes the rotation of fourth sun gear 41.

[0076] When shifting the gear stage of multi-speed transmission 100 to forward tenth speed (F10), second clutch 52, third clutch 53, and first brake 61 are engaged, and first clutch 51, fourth clutch 54, and second brake 62 are disengaged. The engaged second clutch 52 couples first planetary carrier 14 and second sun gear 21 to third planetary carrier 34. The engaged third clutch 53 couples third planetary carrier 34 to fourth sun gear 41. The engaged first brake 61 brakes the rotation of first sun gear 11 and second ring gear 23.

[0077] When shifting the gear position of multi-speed transmission 100 to first reverse gear (R1), third clutch 53, first brake 61, and second brake 62 are engaged, and first clutch 51, second clutch 52, and fourth clutch 54 are disengaged. The engaged third clutch 53 connects third planetary carrier 34 to fourth sun gear 41. The engaged first brake 61 brakes the rotation of first sun gear 11 and second ring gear 23. The engaged second brake 62 brakes the rotation of fourth sun gear 41 and, via third clutch 53, brakes the rotation of third planetary carrier 34.

[0078] Here, for each of planetary gear sets 1 to 4, if the number of teeth of the sun gear is a, the number of teeth of the ring gear is b, the rotation speed ratio of the sun gear is Na, the rotation speed ratio of the ring gear is Nb, and the rotation speed ratio of the planetary carrier is Nc, the following relational expression is established. Note that the rotation speed ratio of each gear refers to the ratio of the rotation speed of each gear to the rotation speed of the input member 7.

[0079] a Na + b Nb = (a + b) Nc The ratio of the number of teeth of the ring gear to the number of teeth of the sun gear (tooth ratio) in each of the planetary gear sets 1 to 4 is as shown in Fig. 3. Fig. 3 is a table showing the tooth ratios in each of the planetary gear sets 1 to 4 of the multi-speed transmission 100 according to the first embodiment.

[0080] The reduction ratio at each of the speed stages shown in FIG. 2 can be determined using the above relational expression and the gear ratio shown in FIG.

[0081] The inter-speed ratio shown in FIG. 2 represents the ratio of the reduction ratios of the respective speed stages. Specifically, the inter-speed ratio is the value obtained by dividing the reduction ratio of the lower speed stage by the reduction ratio of the higher speed stage between adjacent speed stages. The total inter-speed ratio is the value obtained by dividing the reduction ratio of the lowest speed stage by the reduction ratio of the highest speed stage. The multi-speed transmission 100 of this embodiment has 10 forward speed stages. The total inter-speed ratio of the multi-speed transmission 100 of this embodiment is the value obtained by dividing the reduction ratio of the first forward speed stage by the reduction ratio of the tenth forward speed stage.

[0082] The multi-speed transmission 100 of this embodiment has ten forward speed stages and one reverse speed stage, which can improve the fuel economy of a vehicle equipped with the multi-speed transmission 100 and can also improve the driving performance of the vehicle equipped with the multi-speed transmission 100.

[0083] In this embodiment, in order to realize ten forward speeds and one reverse speed, the multi-speed transmission 100 has four planetary gear sets 1 to 4 and a total of six control elements (first to fourth clutches 51 to 54 and first to second brakes 61 to 62). This makes it possible to reduce the weight and size of the multi-speed transmission 100.

[0084] In the multi-speed transmission 100 of this embodiment, the overall gear ratio shown in Fig. 2 is 6.34. This allows the maximum tractive force of a vehicle equipped with the multi-speed transmission 100 to be improved, and also allows the maximum vehicle speed to be improved.

[0085] In the multi-speed transmission 100 of this embodiment, the inter-speed ratios of the 10 forward speed stages shown in Figure 2 are in the range of 1.10 to 1.34, and the variation in the inter-speed ratios is reduced. This allows the multi-speed transmission 100 to suppress shocks during gear changes and to smoothly switch between speed stages.

[0086] When switching between speed stages, the engagement states of two of the six control elements are switched only once, when switching between forward eighth and forward ninth speeds, thereby reducing the impact that occurs when shifting gears. Because the engagement states of the two control elements are switched when switching between speed stages on the high-speed stage side, the frequency of switching the engagement states of the two control elements to switch speed stages can be reduced, and the occurrence of impact can be reduced.

[0087] The only member (shaft) that penetrates the annular first sun gear 11 in the rotational axis direction is the second intermediate coupling member 82 (its portion extending in the rotational axis direction). The number of members (shafts) arranged radially inward of the first sun gear 11 is small, and the diameter of the first sun gear 11 can be made small, so the first planetary gear set 1 can be made more compact. The only member (shaft) that penetrates the annular fourth sun gear 41 in the rotational axis direction is the output member 10. The number of members (shafts) arranged radially inward of the fourth sun gear 41 is small, and the diameter of the fourth sun gear 41 can be made small, so the fourth planetary gear set 4 can be made more compact. Therefore, the multi-speed transmission 100 as a whole can be made more compact.

[0088] The multi-speed transmission 100 does not have a multiple structure in which two or more members (shafts) are arranged radially inward of the sun gear, and does not have a multiple structure in which two or more members (shafts) are arranged radially outward of the ring gear, for each of the planetary gear sets 1 to 4. This simplifies the structure of the multi-speed transmission 100 and improves the durability of the multi-speed transmission 100.

[0089] The third clutch 53 and the fourth clutch 54 are disposed radially away from the rotational axis O. The radial distance between the third clutch 53 and the fourth clutch 54 and the rotational axis O is increased. The third clutch 53 and the fourth clutch 54 are disposed close to the outer periphery of the multi-speed transmission 100 in the radial direction. The third clutch 53 and the fourth clutch 54 may be disposed radially outward of the planet carriers of each planetary gear set. By arranging the third clutch 53 and the fourth clutch 54 in this manner, it becomes easier to plan the layout of oil passages that supply pressure oil for driving the third clutch 53 and the fourth clutch 54, and the degree of freedom in designing the multi-speed transmission 100 can be improved.

[0090] The first clutch 51 and the second clutch 52 are arranged in close proximity to each other. The first clutch 51 and the second clutch 52 are arranged adjacent to each other in the axial direction. The third clutch 53 and the fourth clutch 54 are arranged in close proximity to each other. The third clutch 53 and the fourth clutch 54 are arranged adjacent to each other in the axial direction. By arranging the clutches 51 to 54 in this manner, it becomes easier to plan the layout of the oil passages that supply pressure oil for driving the clutches 51 to 54, and the degree of freedom in designing the multi-speed transmission 100 can be improved.

[0091] Second Embodiment The configuration of a multi-speed transmission 100 according to a second embodiment is the same as that of the first embodiment shown in FIG. 1 , but the gear ratios of the planetary gear sets 1 to 4 of the multi-speed transmission 100 are different from those of the first embodiment described with reference to FIG. 3 .

[0092] 5 is a table showing the gear ratios of the planetary gear sets 1 to 4 of the multi-speed transmission 100 according to the second embodiment. The ratio of the number of teeth of the ring gear to the number of teeth of the sun gear (gear ratio) in each of the planetary gear sets 1 to 4 is as shown in FIG.

[0093] In the multi-speed transmission 100 of the second embodiment configured in this manner, a gear ratio of 10 forward gears and 1 reverse gear can also be achieved by selectively engaging the first to fourth clutches 51 to 54 and the first and second brakes 61 to 62 to restrict the rotation of the rotating elements of the first to fourth planetary gear sets 1 to 4.

[0094] Furthermore, the multi-speed transmission 100 according to the second embodiment differs from the first embodiment in the engagement states of the clutches 51 to 54 or brakes 61 to 62 at specific speed stages. Figure 4 is a table showing the clutches 51 to 54 or brakes 61 to 62 that are engaged at each speed stage of the multi-speed transmission 100 according to the second embodiment.

[0095] Specifically, in multi-speed transmission 100 according to the second embodiment, when the gear is shifted to ninth forward speed (F9), second clutch 52, third clutch 53, and first brake 61 are engaged, and first clutch 51, fourth clutch 54, and second brake 62 are disengaged. The engaged second clutch 52 couples first planetary carrier 14 and second sun gear 21 to third planetary carrier 34. The engaged third clutch 53 couples third planetary carrier 34 to fourth sun gear 41. The engaged first brake 61 brakes the rotation of first sun gear 11 and second ring gear 23.

[0096] When shifting the gear stage of the multi-speed transmission 100 to the tenth forward speed (F10), the second clutch 52, the third clutch 53, and the second brake 62 are engaged, and the first clutch 51, the fourth clutch 54, and the first brake 61 are disengaged. The engaged second clutch 52 connects the first planetary carrier 14 and the second sun gear 21 to the third planetary carrier 34. The engaged third clutch 53 connects the third planetary carrier 34 to the fourth sun gear 41. The engaged second brake 62 brakes the rotation of the fourth sun gear 41 and, via the third clutch 53, brakes the rotation of the third planetary carrier 34.

[0097] In the multi-speed transmission 100 according to the second embodiment, the overall inter-speed ratio is 8.37 as shown in Figure 4, which is larger than the overall inter-speed ratio in the first embodiment, and therefore the maximum tractive force of a vehicle equipped with the multi-speed transmission 100 can be improved, and the maximum vehicle speed can also be improved. The inter-speed ratios of the 10 forward speed stages shown in Figure 4 are in the range of 1.12 to 1.39, and the variation in the inter-speed ratios is kept small, so shocks during gear changes can be suppressed and the speed stages can be switched smoothly.

[0098] The multi-speed transmission 100 of the second embodiment can shift between all 10 forward speeds by simply switching the engagement state of only one of the six control elements, thereby further reducing the shock that occurs when shifting gears.

[0099] 6 is a schematic diagram of a multi-speed transmission 100 according to a third embodiment. In the following description of the third embodiment, the description will be omitted for the same configuration as the first embodiment, and will focus on the configuration unique to the third embodiment that differs from the first embodiment.

[0100] In the multi-speed transmission 100 according to the third embodiment, as shown in Fig. 6 , the first intermediate connecting member 81 is configured to rotate integrally with the second planetary carrier 24. More specifically, the first intermediate connecting member 81 is fixed to the second planetary carrier 24. The first intermediate connecting member 81 and the second planetary carrier 24 may be configured as a single member. The first intermediate connecting member 81 connects the first sun gear 11 and the second planetary carrier 24. The first sun gear 11 and the second planetary carrier 24 are configured to rotate integrally with each other.

[0101] The first brake 61 is configured to selectively connect the second ring gear 23 and the housing 9 together.

[0102] When engaged, the first brake 61 connects the second ring gear 23 to the housing 9. When engaged, the first brake 61 brakes the rotation of the second ring gear 23, preventing the second ring gear 23 from rotating. When released, the first brake 61 releases the connection between the second ring gear 23 and the housing 9. When released, the first brake 61 does not brake the rotation of the second ring gear 23, allowing the second ring gear 23 to rotate.

[0103] Fig. 7 is a table showing the clutches 51 to 54 or brakes 61 to 62 that are engaged at each speed stage of the multi-speed transmission 100 according to the third embodiment. In the multi-speed transmission 100 according to the third embodiment, the engagement states of the clutches 51 to 54 or brakes 61 to 62 at each speed stage are the same as in the first embodiment. Fig. 8 is a table showing the gear ratios of the planetary gear sets 1 to 4 of the multi-speed transmission 100 according to the third embodiment. In each of the planetary gear sets 1 to 4, the ratio of the number of teeth of the ring gear to the number of teeth of the sun gear (tooth ratio) is as shown in Fig. 8.

[0104] In the multi-speed transmission 100 of the third embodiment configured in this manner, a gear ratio of 10 forward gears and 1 reverse gear can also be achieved by selectively engaging the first to fourth clutches 51 to 54 and the first and second brakes 61 to 62 to restrict the rotation of the rotating elements of the first to fourth planetary gear sets 1 to 4.

[0105] 7 is 6.43, it is possible to improve the maximum tractive force and also the maximum vehicle speed of a vehicle equipped with multi-speed transmission 100. The inter-speed ratios of the 10 forward speed stages shown in FIG. 7 are in the range of 1.08 to 1.39, and the variation in the inter-speed ratios is kept small, so it is possible to suppress shocks during gear changes and to switch between speed stages smoothly.

[0106] The multi-speed transmission 100 of the above-described embodiment can be used in any machine equipped with a multi-speed transmission, but is particularly applicable to construction and mining machines such as dump trucks.

[0107] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0108] 1 First planetary gear set, 2 Second planetary gear set, 3 Third planetary gear set, 4 Fourth planetary gear set, 7 Input member, 9 Housing, 10 Output member, 11 First sun gear, 12 First planetary gear, 13 First ring gear, 14 First planetary carrier, 21 Second sun gear, 22 Second planetary gear, 23 Second ring gear, 24 Second planetary carrier, 31 Third sun gear, 32 Third planetary gear, 33 Third ring gear, 34 Third planetary carrier, 41 Fourth sun gear, 42 Fourth planetary gear, 43 Fourth ring gear, 44 Fourth planetary carrier, 51 First clutch, 52 Second clutch, 53 Third clutch, 54 Fourth clutch, 61 First brake, 62 Second brake, 81 First intermediate connecting member, 82 Second intermediate connecting member, 83 Third intermediate connecting member, 84 Fourth intermediate connecting member, 100 multi-speed transmission, O rotation axis.

Claims

1. A multi-speed transmission comprising: an input member; an output member; four or less planetary gear sets including a first planetary gear set, a second planetary gear set, a third planetary gear set, and a fourth planetary gear set arranged axially in that order from the input member to the output member, each planetary gear set including a plurality of rotating elements including a sun gear, a planet carrier, and a ring gear; and six or less control elements, each of the six or less control elements operatively coupled to at least one planetary gear set of the four or less planetary gear sets and selectively engageable to generate a set of different gear ratios between the input member and the output member, the set of different gear ratios including at least ten forward gear ratios and at least one reverse gear ratio, and one control element of the six or less control elements selectively connects the planet carrier of the first planetary gear set and the ring gear of the fourth planetary gear set.

2. A multi-speed transmission comprising: an input member; an output member; four or less planetary gear sets including a first planetary gear set, a second planetary gear set, a third planetary gear set and a fourth planetary gear set arranged axially in that order from the input member to the output member, each planetary gear set including a plurality of rotating elements including a sun gear, a planet carrier and a ring gear; and six or less control elements, each of the six or less control elements operatively coupled to at least one planetary gear set of the four or less planetary gear sets and selectively engageable to generate a set of different gear ratios between the input member and the output member, the set of different gear ratios including at least ten forward gear ratios and at least one reverse gear ratio, and one control element of the six or less control elements selectively connects the sun gear of the second planetary gear set and the sun gear of the third planetary gear set.

3. A multi-speed transmission according to claim 1 or 2, wherein one control element of the six or less control elements selectively connects the sun gear of the second planetary gear set and the ring gear of the fourth planetary gear set.

4. A multi-speed transmission as set forth in claim 1 or claim 2, wherein one control element of the six or less control elements selectively connects the sun gear of the second planetary gear set with the planet carrier of the third planetary gear set.

5. A multi-speed transmission according to claim 1 or 2, further comprising an intermediate connecting member connecting the planet carrier of the first planetary gear set and the sun gear of the second planetary gear set.

6. A multi-speed transmission according to claim 1 or 2, further comprising an intermediate connecting member connecting the planet carrier of the second planetary gear set and the ring gear of the third planetary gear set.

7. A multi-speed transmission according to claim 1 or 2, further comprising an intermediate connecting member connecting the sun gear of the third planetary gear set and the ring gear of the fourth planetary gear set.

8. A multi-speed transmission according to claim 1 or claim 2, wherein the input member is connected to the ring gear of the first planetary gear set.

9. A multi-speed transmission according to claim 1 or claim 2, wherein the output member is connected to the planet carrier of the fourth planetary gear set.

10. A multi-speed transmission as claimed in claim 1 or claim 2, wherein one control element of the six or less control elements selectively connects the planet carrier of the first planetary gear set and the sun gear of the third planetary gear set.

11. A multi-speed transmission as claimed in claim 1 or claim 2, wherein one control element of the six or less control elements selectively connects the planet carrier of the first planetary gear set with the planet carrier of the third planetary gear set.

12. A multi-speed transmission as claimed in claim 1 or 2, wherein one control element of the six or less control elements selectively connects the planet carrier of the third planetary gear set and the sun gear of the fourth planetary gear set.

13. A multi-speed transmission as claimed in claim 1 or claim 2, wherein one control element of the six or less control elements selectively connects the planet carrier of the third planetary gear set with the planet carrier of the fourth planetary gear set.

14. A multi-speed transmission as claimed in claim 1 or claim 2, wherein one control element of the six or less control elements selectively connects the planet carrier of the third planetary gear set with the output member.

15. A multi-speed transmission according to claim 1 or claim 2, wherein one control element of said six or less control elements brakes the rotation of said ring gear of said second planetary gear set.

16. A multi-speed transmission according to claim 1 or claim 2, wherein one control element of the six or fewer control elements brakes the rotation of the sun gear of the fourth planetary gear set.

Images