Multi-stage transmission

Abstract

To reduce variation in an inter-stage ratio.SOLUTION: A multistage transmission 100 comprises: an input member 7; an output member 10; first to fourth planetary gear sets 1 to 4 arranged axially in order from the input member 7 to the output member 10 and each including a sun gear, a planet carrier and a ring gear; first to third clutches 51 to 53; and first to third brakes 61 to 63. Each of the first to third clutches 51 to 53 and the first to third brakes 61 to 63 is operatively connected to at least one planetary gear set of the planetary gear sets 1 to 4, and is selectively engageable between the input member 7 and the output member 10 so as to produce a set of different gear ratios including at least ten forward gear ratios and at least two reverse gear ratios. The first clutch 51 selectively connects a third sun gear 31 of the third planetary gear set 3 and a fourth planetary carrier 44 of the fourth planetary gear set 4.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Work vehicles such as dump trucks are equipped with a multi-stage transmission having a plurality of planetary gear sets. A planetary multi-stage transmission can obtain a desired reduction ratio by appropriately combining the rotating elements of each planetary gear set. Conventionally, for example, a multi-stage transmission having four planetary gear sets and six control elements and capable of generating ten forward speeds and two reverse speeds is disclosed in US Patent Application Publication No. 2015 / 0267781 (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a multi-stage transmission, reduction of variation in the ratio between stages is desired for smooth switching between speed stages.

[0005] The present disclosure proposes a multi-stage transmission capable of reducing variation in the ratio between stages.

Means for Solving the Problems

[0006] A multi-speed transmission according to an aspect of the present disclosure includes an input member and an output member. The multi-speed transmission includes four or fewer planetary gear sets. The four or fewer 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 that are arranged axially in order from the input member toward the output member. Each planetary gear set includes a sun gear, a planetary carrier, and a ring gear. The multi-speed transmission includes six or fewer control elements. Each of the six or fewer control elements is operably coupled to at least one of the four or fewer 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 two reverse gear ratios. One of the six or fewer control elements selectively couples the sun gear of the third planetary gear set and the planetary carrier of the fourth planetary gear set.

Advantages of the Invention

[0007] According to the multi-speed transmission of the present disclosure, it is possible to reduce the variation in the step ratio.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0009] Hereinafter, each embodiment of the multi-stage transmission 100 will be described with reference to the drawings. In each of the embodiments described below, the same or corresponding parts may be denoted by the same reference numerals, and redundant descriptions may not be repeated.

[0010] [First Embodiment] FIG. 1 is a schematic diagram of the multi-stage transmission 100 according to the first embodiment. The multi-stage transmission 100 changes the rotational speed of the power input from an arbitrary drive source (not shown), such as an internal combustion engine represented by a diesel engine or an electric motor, and outputs it. The power from the drive source may be input to the multi-stage transmission 100 via a torque converter.

[0011] The multi-stage transmission 100 includes a plurality of planetary gear sets 1 to 4, a plurality of clutches 51 to 53, a plurality of brakes 61 to 63, 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. Each of the planetary gear sets 1 to 4, each of the clutches 51 to 53, each of the brakes 61 to 63, 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 housed in the housing 9.

[0012] In the following description, the rotation axis O indicates the center lines of the input member 7 and the output member 10. The rotation axis direction indicates the direction in which the rotation axis O extends. The radial direction indicates the radial direction of a circle centered on the rotation axis O. In FIGS. 1 and subsequent FIGS. 4, 6, and 8, the rotation axis direction is the left-right direction in the figures, and the radial direction is the up-down direction in the figures. The input side indicates the side where the multi-stage transmission 100 inputs power. The output side indicates the side where the multi-stage transmission 100 outputs power. In FIGS. 1 and subsequent FIGS. 4, 6, and 8, the input side is the left side in the figures, and the output side is the right side in the figures.

[0013] The plurality of planetary gear sets includes 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 plurality of clutches includes a first clutch 51, a second clutch 52, and a third clutch 53. The plurality of brakes includes a first brake 61, a second brake 62, and a third brake 63. Each of the clutches 51 to 53 and each of the brakes 61 to 63 corresponds to a control element of the embodiment. The six control elements include a first clutch 51, a second clutch 52, a third clutch 53, a first brake 61, a second brake 62, and a third brake 63.

[0014] 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 rotatably supported about the 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. Specifically, they are arranged in the order of 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 from the input side to the output side.

[0015] The input member 7 is configured to rotate about the rotation axis O. Power from a drive source such as an engine is input to the input member 7.

[0016] The first intermediate coupling member 81 is configured to rotate about the rotation axis O. The first intermediate coupling member 81 has a portion extending in the rotation axis direction. The center line of the first intermediate coupling member 81 and the center line of the input member 7 are substantially the same.

[0017] The second intermediate coupling member 82 is configured to rotate about the rotation axis O. The second intermediate coupling member 82 has a portion extending in the rotation axis direction. The portion of the second intermediate coupling member 82 extending in the rotation axis direction is disposed radially inward with respect to the portion of the first intermediate coupling member 81 extending in the rotation axis direction. The center line of the second intermediate coupling member 82 and the center line of the input member 7 are substantially the same.

[0018] The third intermediate coupling member 83 is configured to rotate about the rotation axis O. The third intermediate coupling member 83 has a portion extending in the rotation axis direction. The center line of the third intermediate coupling member 83 and the center line of the input member 7 are substantially the same.

[0019] The fourth intermediate coupling member 84 is configured to rotate about the rotation axis O. The fourth intermediate coupling member 84 has a portion extending in the rotation axis direction. The center line of the fourth intermediate coupling member 84 and the center line of the input member 7 are substantially the same.

[0020] The first planetary gear set 1 is a single-pinion type planetary gear mechanism. The first planetary gear set 1 has, as rotational elements, a first sun gear 11, a plurality of first planetary gears 12, a first ring gear 13, and a first planetary carrier 14.

[0021] The first sun gear 11 is rotatably disposed about the rotation axis O. The first sun gear 11 is disposed radially outside the input member 7. Specifically, the first sun gear 11 is annular, and the input member 7 passes through the first sun gear 11. The first sun gear 11 and the input member 7 are relatively rotatable.

[0022] The first sun gear 11 is configured to rotate integrally with the first intermediate coupling member 81. Specifically, the first sun gear 11 is fixed to the first intermediate coupling member 81. The first sun gear 11 and the first intermediate coupling member 81 may be formed of one member.

[0023] Each first planetary gear 12 is configured to mesh with the first sun gear 11. Each first planetary gear 12 is disposed radially outside the first sun gear 11. Specifically, each first planetary gear 12 is disposed at intervals in the circumferential direction.

[0024] Each first planetary gear 12 is configured to revolve around the first sun gear 11. Each first planetary gear 12 is configured to rotate about the rotation axis O. Also, each first planetary gear 12 is configured to rotate on its own axis.

[0025] The first ring gear 13 meshes with each first planetary gear 12. The first ring gear 13 is configured to rotate about the rotation axis O.

[0026] The first ring gear 13 is configured to rotate integrally with the second intermediate coupling member 82. Specifically, the first ring gear 13 is fixed to the second intermediate coupling member 82. The first ring gear 13 and the second intermediate coupling member 82 may be formed of one member.

[0027] The first planetary carrier 14 supports each first planetary gear 12. Each first planetary gear 12 is rotatable on its own axis while being supported by the first planetary carrier 14. The first planetary carrier 14 is configured to rotate about the rotation axis O.

[0028] The second planetary gear set 2 is a single-pinion type planetary gear mechanism. The second planetary gear set 2 has, as rotating elements, a second sun gear 21, a plurality of second planetary gears 22, a second ring gear 23, and a second planetary carrier 24.

[0029] The second sun gear 21 is configured to be rotatable about the rotation axis O. The second sun gear 21 is disposed radially outside the input member 7. Specifically, the second sun gear 21 is annular, and the input member 7 penetrates through the second sun gear 21. The second sun gear 21 and the input member 7 are relatively rotatable.

[0030] The second sun gear 21 is configured to rotate integrally with the second intermediate coupling member 82. Specifically, the second sun gear 21 is fixed to the second intermediate coupling member 82. The second sun gear 21 and the second intermediate coupling member 82 may be formed by one member. The second intermediate coupling member 82 connects the first ring gear 13 of the first planetary gear set 1 and the second sun gear 21 of the second planetary gear set 2. The first ring gear 13 and the second sun gear 21 are configured to rotate integrally with each other.

[0031] Each second planetary gear 22 is configured to mesh with the second sun gear 21. Each second planetary gear 22 is disposed radially outside the second sun gear 21. Specifically, each second planetary gear 22 is arranged at intervals in the circumferential direction.

[0032] Each second planetary gear 22 is configured to revolve around the second sun gear 21. Each second planetary gear 22 is configured to rotate about the rotation axis O. Also, each second planetary gear 22 is configured to rotate on its own axis.

[0033] The second ring gear 23 meshes with each second planetary gear 22. The second ring gear 23 is configured to rotate about the rotation axis O.

[0034] The second ring gear 23 is configured to rotate integrally with the first intermediate coupling member 81. Specifically, the second ring gear 23 is fixed to the first intermediate coupling member 81. The second ring gear 23 and the first intermediate coupling member 81 may be formed by one member.

[0035] The second planetary carrier 24 supports each second planetary gear 22. Each second planetary gear 22 is rotatable while being supported by the second planetary carrier 24. The second planetary carrier 24 is configured to rotate about the rotation axis O.

[0036] The second planetary carrier 24 is configured to rotate integrally with the third intermediate coupling member 83. 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 one member.

[0037] The third planetary gear set 3 is a single-pinion type planetary gear mechanism. The third planetary gear set 3 has, as rotational elements, a third sun gear 31, a plurality of third planetary gears 32, a third ring gear 33, and a third planetary carrier 34.

[0038] The third sun gear 31 is configured to rotate integrally with the input member 7. Specifically, the third sun gear 31 is fixed to the input member 7. The input member 7 is connected to the third sun gear 31 of the third planetary gear set 3. The third sun gear 31 and the input member 7 may be formed by one member.

[0039] Each third planetary gear 32 is configured to mesh with the third sun gear 31. Each third planetary gear 32 is disposed radially outside the third sun gear 31. Specifically, each third planetary gear 32 is disposed at intervals in the circumferential direction.

[0040] Each third planetary gear 32 is configured to revolve around the third sun gear 31. Each third planetary gear 32 is configured to rotate about the rotation axis O. Further, each third planetary gear 32 is configured to rotate itself.

[0041] The third ring gear 33 meshes with each third planetary gear 32. The third ring gear 33 is configured to rotate about the axis of rotation O.

[0042] The third ring gear 33 is configured to rotate integrally with the third intermediate coupling member 83. Specifically, the third ring gear 33 is fixed to the third intermediate coupling member 83. The third ring gear 33 and the third intermediate coupling member 83 may be formed of a single member. The third intermediate coupling 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.

[0043] The third planetary carrier 34 supports each third planetary gear 32. Each third planetary gear 32 is rotatable about its own axis while being supported by the third planetary carrier 34. The third planetary carrier 34 is configured to rotate about the axis of rotation O.

[0044] The fourth planetary gear set 4 is a single-pinion type planetary gear mechanism. The fourth planetary gear set 4 has, as rotational elements, a fourth sun gear 41, a plurality of fourth planetary gears 42, a fourth ring gear 43, and a fourth planetary carrier 44.

[0045] The fourth sun gear 41 is annular and is disposed so as to be rotatable about the axis of rotation O. The fourth sun gear 41 is configured to rotate integrally with the first intermediate coupling member 81. Specifically, the fourth sun gear 41 is fixed to the first intermediate coupling member 81. The fourth sun gear 41 and the first intermediate coupling member 81 may be formed of a single member. The first intermediate coupling member 81 connects the first sun gear 11 of the first planetary gear set 1, the second ring gear 23 of the second planetary gear set 2, and the fourth sun gear 41 of the fourth planetary gear set 4. The first sun gear 11, the second ring gear 23, and the fourth sun gear 41 are configured to rotate integrally with each other.

[0046] Each fourth planetary gear 42 is configured to mesh with a fourth sun gear 41. Each fourth planetary gear 42 is disposed radially outside the fourth sun gear 41. Specifically, the fourth planetary gears 42 are arranged at intervals in the circumferential direction.

[0047] 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 the rotation axis O. Further, each fourth planetary gear 42 is configured to rotate on its own axis.

[0048] A fourth ring gear 43 meshes with each fourth planetary gear 42. The fourth ring gear 43 is configured to rotate about the rotation axis O.

[0049] The fourth ring gear 43 is configured to rotate integrally with the output member 10. The fourth ring gear 43 is fixed to the output member 10. The output member 10 is connected to the fourth ring gear 43 of the fourth planetary gear set 4. The fourth ring gear 43 and the output member 10 may be formed by one member. The output member 10 outputs power. Specifically, the output member 10 outputs power having a rotational speed that has been shifted by a multi-stage transmission 100.

[0050] A fourth planetary carrier 44 supports each fourth planetary gear 42. Each fourth planetary gear 42 is rotatable on its own axis while being supported by the fourth planetary carrier 44. The fourth planetary carrier 44 is configured to rotate about the rotation axis O.

[0051] The fourth planetary carrier 44 is configured to rotate integrally with a fourth intermediate coupling member 84. Specifically, the fourth planetary carrier 44 is fixed to the fourth intermediate coupling member 84. The fourth planetary carrier 44 and the fourth intermediate coupling member 84 may be formed by one member.

[0052] The first clutch 51 is configured to selectively connect the third sun gear 31 of the third planetary gear set 3 and the fourth intermediate coupling member 84. The first clutch 51 is configured to selectively connect the third sun gear 31 and the fourth planetary carrier 44 of the fourth planetary gear set 4. The first clutch 51 is, for example, a hydraulic clutch mechanism and can be composed of a plurality of disks.

[0053] When the first clutch 51 is in the engaged state, it connects the third sun gear 31 and the fourth intermediate coupling member 84. When the first clutch 51 is in the engaged state, it connects the third sun gear 31 and the fourth planetary carrier 44 via the fourth intermediate coupling member 84. Therefore, the third sun gear 31 and the fourth planetary carrier 44 rotate integrally. When the first clutch 51 is in the released state, it releases the connection between the third sun gear 31 and the fourth intermediate coupling member 84. Therefore, the third sun gear 31 and the fourth planetary carrier 44 are rotatable relative to each other.

[0054] The second clutch 52 is configured to selectively connect the third planetary carrier 34 of the third planetary gear set 3 and the first intermediate coupling member 81. The second clutch 52 is configured to selectively connect the third planetary carrier 34 and the first sun gear 11, the second ring gear 23, and the fourth sun gear 41. The second clutch 52 is, for example, a hydraulic clutch mechanism and can be composed of a plurality of disks.

[0055] When the second clutch 52 is in the engaged state, it connects the third planetary carrier 34 and the first intermediate coupling member 81. When the second clutch 52 is in the engaged state, it connects the third planetary carrier 34, the first sun gear 11, the second ring gear 23, and the fourth sun gear 41 via the first intermediate coupling member 81. Therefore, the third planetary carrier 34, the first sun gear 11, the second ring gear 23, and the fourth sun gear 41 rotate integrally. When the second clutch 52 is in the released state, it releases the connection between the third planetary carrier 34 and the first intermediate coupling member 81. Therefore, the third planetary carrier 34 is rotatable relative to the first sun gear 11, the second ring gear 23, and the fourth sun gear 41.

[0056] The third clutch 53 is configured to selectively connect the third planetary carrier 34 of the third planetary gear set 3 and the fourth intermediate coupling member 84. The third clutch 53 is configured to selectively connect the third planetary carrier 34 and the fourth planetary carrier 44 of the fourth planetary gear set 4. The third clutch 53 is, for example, a hydraulic clutch mechanism and can be composed of a plurality of disks.

[0057] When the third clutch 53 is in the engaged state, it connects the third planetary carrier 34 and the fourth intermediate coupling member 84. When the third clutch 53 is in the engaged state, it connects the third planetary carrier 34 and the fourth planetary carrier 44 via the fourth intermediate coupling member 84. Therefore, the third planetary carrier 34 and the fourth planetary carrier 44 rotate integrally. When the third clutch 53 is in the released state, it releases the connection between the third planetary carrier 34 and the fourth intermediate coupling member 84. Therefore, the third planetary carrier 34 and the fourth planetary carrier 44 are rotatable relative to each other.

[0058] The first brake 61 is configured to selectively connect the second intermediate coupling member 82 and the housing 9. The first brake 61 is configured to selectively connect the first ring gear 13 of the first planetary gear set 1 and the second sun gear 21 of the second planetary gear set 2 and the housing 9.

[0059] When in the engaged state, the first brake 61 connects the second intermediate coupling member 82 and the housing 9. When in the engaged state, the first brake 61 connects the first ring gear 13 and the housing 9, and connects the second sun gear 21 and the housing 9. The first brake 61 in the engaged state brakes the rotation of the first ring gear 13 and the second sun gear 21, and the first ring gear 13 and the second sun gear 21 are made non-rotatable.

[0060] When in the released state, the first brake 61 releases the connection between the second intermediate coupling member 82 and the housing 9. When in the released state, the first brake 61 releases the connection between the first ring gear 13 and the housing 9, and releases the connection between the second sun gear 21 and the housing 9. The first brake 61 in the released state does not brake the rotation of the first ring gear 13 and the second sun gear 21, and the first ring gear 13 and the second sun gear 21 are rotatable.

[0061] The second brake 62 is configured to selectively connect the first planet carrier 14 of the first planetary gear set 1 and the housing 9.

[0062] When in the engaged state, the second brake 62 connects the first planet carrier 14 and the housing 9. The second brake 62 in the engaged state brakes the rotation of the first planet carrier 14, and the first planet carrier 14 is made non-rotatable. When in the released state, the second brake 62 releases the connection between the first planet carrier 14 and the housing 9. The second brake 62 in the released state does not brake the rotation of the first planet carrier 14, and the first planet carrier 14 is rotatable.

[0063] The third brake 63 is configured to selectively connect the fourth planet carrier 44 of the fourth planetary gear set 4 and the housing 9.

[0064] When the third brake 63 is in the engaged state, it connects the fourth planetary carrier 44 and the housing 9. The engaged third brake 63 brakes the rotation of the fourth planetary carrier 44, and the fourth planetary carrier 44 is rendered non-rotatable. When the third brake 63 is in the released state, it releases the connection between the fourth planetary carrier 44 and the housing 9. The released third brake 63 does not brake the rotation of the fourth planetary carrier 44, and the fourth planetary carrier 44 is rotatable.

[0065] In the multi-stage transmission 100 configured as described above, each of the first to third clutches 51 to 53 and the first to third brakes 61 to 63 is operably coupled to at least one of the first to fourth planetary gear sets 1 to 4. By selectively engaging the first to third clutches 51 to 53 and the first to third brakes 61 to 63 to regulate 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 two reverse gear ratios.

[0066] FIG. 2 is a table showing the clutches 51 to 53 or the brakes 61 to 63 that are in the engaged state at each speed stage of the multi-stage transmission 100. In FIG. 2, the operating states of the first to third clutches 51 to 53 and the first to third brakes 61 to 63 corresponding to each speed stage are illustrated. When an "X" mark is placed in the columns of the first to third clutches 51 to 53 and the first to third brakes 61 to 63, it indicates that they are in the engaged state, and when the column is blank, it indicates that they are in the released (non-engaged) state.

[0067] When setting the speed stage of the multi-stage transmission 100 to the first forward speed (F1), the third clutch 53, the first brake 61, and the third brake 63 are placed in the engaged state, and the first clutch 51, the second clutch 52, and the second brake 62 are placed in the released state. The engaged third clutch 53 connects the third planetary carrier 34 and the fourth planetary carrier 44. The engaged first brake 61 brakes the rotation of the first ring gear 13 and the second sun gear 21. The engaged third brake 63 brakes the rotation of the fourth planetary carrier 44.

[0068] When setting the speed stage of the multi-stage transmission 100 to the second forward speed (F2), engage the third clutch 53, the second brake 62, and the third brake 63, and release the first clutch 51, the second clutch 52, and the first brake 61. The engaged third clutch 53 connects the third planetary carrier 34 and the fourth planetary carrier 44. The engaged second brake 62 brakes the rotation of the first planetary carrier 14. The engaged third brake 63 brakes the rotation of the fourth planetary carrier 44.

[0069] When setting the speed stage of the multi-stage transmission 100 to the third forward speed (F3), engage the third clutch 53, the first brake 61, and the second brake 62, and release the first clutch 51, the second clutch 52, and the third brake 63. The engaged third clutch 53 connects the third planetary carrier 34 and the fourth planetary carrier 44. The engaged first brake 61 brakes the rotation of the first ring gear 13 and the second sun gear 21. The engaged second brake 62 brakes the rotation of the first planetary carrier 14.

[0070] When setting the speed stage of the multi-stage transmission 100 to the fourth forward speed (F4), engage the second clutch 52, the third clutch 53, and the second brake 62, and release the first clutch 51, the first brake 61, and the third brake 63. The engaged second clutch 52 connects the third planetary carrier 34 with the first sun gear 11, the second ring gear 23, and the fourth sun gear 41. The engaged third clutch 53 connects the third planetary carrier 34 and the fourth planetary carrier 44. The engaged second brake 62 brakes the rotation of the first planetary carrier 14.

[0071] When setting the speed stage of the multi-stage transmission 100 to the fifth forward speed (F5), engage the second clutch 52, the third clutch 53, and the first brake 61, and release the first clutch 51, the second brake 62, and the third brake 63. The engaged second clutch 52 connects the third planetary carrier 34 to the first sun gear 11, the second ring gear 23, and the fourth sun gear 41. The engaged third clutch 53 connects the third planetary carrier 34 to the fourth planetary carrier 44. The engaged first brake 61 brakes the rotation of the first ring gear 13 and the second sun gear 21.

[0072] When setting the speed stage of the multi-stage transmission 100 to the sixth forward speed (F6), engage the first clutch 51, the third clutch 53, and the second brake 62, and release the second clutch 52, the first brake 61, and the third brake 63. The engaged first clutch 51 connects the third sun gear 31 to the fourth planetary carrier 44. The engaged third clutch 53 connects the third planetary carrier 34 to the fourth planetary carrier 44. The engaged second brake 62 brakes the rotation of the first planetary carrier 14.

[0073] When setting the speed stage of the multi-stage transmission 100 to the seventh forward speed (F7), engage the first clutch 51, the third clutch 53, and the first brake 61, and release the second clutch 52, the second brake 62, and the third brake 63. The engaged first clutch 51 connects the third sun gear 31 to the fourth planetary carrier 44. The engaged third clutch 53 connects the third planetary carrier 34 to the fourth planetary carrier 44. The engaged first brake 61 brakes the rotation of the first ring gear 13 and the second sun gear 21.

[0074] When setting the speed stage of the multi-stage transmission 100 to the 8th forward speed (F8), engage the first clutch 51, the second clutch 52, and the third clutch 53, and release the first brake 61, the second brake 62, and the third brake 63. The engaged first clutch 51 connects the third sun gear 31 and the fourth planetary carrier 44. The engaged second clutch 52 connects the third planetary carrier 34 to the first sun gear 11, the second ring gear 23, and the fourth sun gear 41. The engaged third clutch 53 connects the third planetary carrier 34 and the fourth planetary carrier 44.

[0075] When setting the speed stage of the multi-stage transmission 100 to the 9th forward speed (F9), engage the first clutch 51, the second clutch 52, and the second brake 62, and release the third clutch 53, the first brake 61, and the third brake 63. The engaged first clutch 51 connects the third sun gear 31 and the fourth planetary carrier 44. The engaged second clutch 52 connects the third planetary carrier 34 to the first sun gear 11, the second ring gear 23, and the fourth sun gear 41. The engaged second brake 62 brakes the rotation of the first planetary carrier 14.

[0076] When setting the speed stage of the multi-stage transmission 100 to the 10th forward speed (F10), engage the first clutch 51, the first brake 61, and the second brake 62, and release the second clutch 52, the third clutch 53, and the third brake 63. The engaged first clutch 51 connects the third sun gear 31 and the fourth planetary carrier 44. The engaged first brake 61 brakes the rotation of the first ring gear 13 and the second sun gear 21. The engaged second brake 62 brakes the rotation of the first planetary carrier 14.

[0077] When setting the speed stage of the multi-stage transmission 100 to the first reverse speed (R1), engage the second clutch 52, the second brake 62, and the third brake 63, and disengage the first clutch 51, the third clutch 53, and the first brake 61. The engaged second clutch 52 connects the third planetary carrier 34 to the first sun gear 11, the second ring gear 23, and the fourth sun gear 41. The engaged second brake 62 brakes the rotation of the first planetary carrier 14. The engaged third brake 63 brakes the rotation of the fourth planetary carrier 44.

[0078] When setting the speed stage of the multi-stage transmission 100 to the second reverse speed (R2), engage the second clutch 52, the first brake 61, and the third brake 63, and disengage the first clutch 51, the third clutch 53, and the second brake 62. The engaged second clutch 52 connects the third planetary carrier 34 to the first sun gear 11, the second ring gear 23, and the fourth sun gear 41. The engaged first brake 61 brakes the rotation of the first ring gear 13 and the second sun gear 21. The engaged third brake 63 brakes the rotation of the fourth planetary carrier 44.

[0079] When setting the speed stage of the multi-stage transmission 100 to the ninth forward speed (F9’), which is an alternative speed stage, engage the first clutch 51, the second clutch 52, and the first brake 61, and disengage the third clutch 53, the second brake 62, and the third brake 63. The engaged first clutch 51 connects the third sun gear 31 to the fourth planetary carrier 44. The engaged second clutch 52 connects the third planetary carrier 34 to the first sun gear 11, the second ring gear 23, and the fourth sun gear 41. The engaged first brake 61 brakes the rotation of the first ring gear 13 and the second sun gear 21.

[0080] Here, for each planetary gear set 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 expressions hold. 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.

[0081] a·Na + b·Nb = (a + b)·Nc 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 number ratio) is as shown in FIG. 3. Note that FIG. 3 is a table showing the tooth number ratios in each of the planetary gear sets 1 to 4 of the multi-stage transmission 100 according to the first embodiment.

[0082] The reduction ratios in each of the above-described speed stages shown in FIG. 2 can be obtained using the above relational expression and the tooth number ratios shown in FIG. 3.

[0083] Note that the inter-stage ratio shown in FIG. 2 represents the ratio of the reduction ratios of each speed stage. Specifically, regarding the reduction ratios of adjacent speed stages, the value obtained by dividing the reduction ratio of the low speed stage by the reduction ratio of the high speed stage is defined as the inter-stage ratio. The total inter-stage ratio refers to the value obtained by dividing the reduction ratio of the lowest speed stage by the reduction ratio of the highest speed stage. The multi-stage transmission 100 of the present embodiment has ten forward speed stages. The total inter-stage ratio of the multi-stage transmission 100 of the present embodiment is the value obtained by dividing the reduction ratio of the first forward speed by the reduction ratio of the tenth forward speed.

[0084] The multi-stage transmission 100 of the present embodiment has ten forward speed stages and two reverse speed stages. Thereby, the fuel efficiency of a vehicle equipped with the multi-stage transmission 100 can be improved, and the running performance of a vehicle equipped with the multi-stage transmission 100 can be enhanced.

[0085] In the present embodiment, in order to realize ten forward speed stages and two reverse speed stages, the multi-stage transmission 100 has four planetary gear sets 1 to 4 and a total of six control elements (the first to third clutches 51 to 53 and the first to third brakes 61 to 63). Thereby, weight reduction and downsizing of the multi-stage transmission 100 can be achieved.

[0086] In the multi-stage transmission 100 of the present embodiment, the total inter-stage ratio shown in FIG. 2 is 6.92. Thereby, the maximum traction force of a vehicle equipped with the multi-stage transmission 100 can be improved, and the maximum vehicle speed can also be increased.

[0087] In the multi-stage transmission 100 of the present embodiment, as shown in FIG. 2, the ratio between adjacent speed steps of the ten forward speed steps is in the range of 1.14 to 1.33, and the variation in the ratio between adjacent speed steps is reduced. As a result, the multi-stage transmission 100 can suppress the shock during gear shifting and can smoothly switch the speed steps.

[0088] [Second Embodiment] FIG. 4 is a schematic diagram of the multi-stage transmission 100 according to the second embodiment. FIG. 5 is a table showing the tooth number ratios in each of the planetary gear sets 1 to 4 of the multi-stage transmission 100 according to the second embodiment. In the following description of the second embodiment, the description of the same configuration as that of the first embodiment will be omitted, and the description will focus on the configuration specific to the second embodiment that is different from the first embodiment.

[0089] The multi-stage transmission 100 according to the second embodiment is different from the first embodiment in that, as shown in FIG. 5, four or fewer planetary gear sets 1 to 4 include at least one double pinion type planetary gear mechanism. Specifically, in the multi-stage transmission 100 according to the second embodiment, the first planetary gear set 1 is configured as a double pinion type planetary gear mechanism.

[0090] The first planetary gear 12 of the first planetary gear set 1 has an inner pinion gear and an outer pinion gear. The inner pinion gear meshes with the first sun gear 11. The outer pinion gear meshes with the first ring gear 13. The inner pinion gear and the outer pinion gear also mesh with each other. The inner pinion gear is arranged radially inwardly away from the first ring gear 13, and the outer pinion gear is arranged radially outwardly away from the first sun gear 11. The first planetary carrier 14 rotatably supports both the inner pinion gear and the outer pinion gear.

[0091] As shown in FIG. 4, the first planetary carrier 14 is configured to rotate integrally with the second intermediate coupling member 82. 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. The second intermediate coupling 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.

[0092] The first brake 61 is configured to selectively connect 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 to the housing 9.

[0093] When the first brake 61 is in the engaged state, it connects the first planetary carrier 14 to the housing 9 and connects the second sun gear 21 to the housing 9. The engaged first brake 61 brakes the rotation of the first planetary carrier 14 and the second sun gear 21, and the first planetary carrier 14 and the second sun gear 21 are rendered non-rotatable. When the first brake 61 is in the released state, it releases the connection between the first planetary carrier 14 and the housing 9 and releases the connection between the second sun gear 21 and the housing 9. The released first brake 61 does not brake the rotation of the first planetary carrier 14 and the second sun gear 21, and the first planetary carrier 14 and the second sun gear 21 are rotatable.

[0094] The second brake 62 is configured to selectively connect the first ring gear 13 of the first planetary gear set 1 to the housing 9.

[0095] When the second brake 62 is in the engaged state, it connects the first ring gear 13 and the housing 9. When the second brake 62 is in the engaged state, it brakes the rotation of the first ring gear 13, and the first ring gear 13 is rendered non-rotatable. When the second brake 62 is in the released state, it releases the connection between the first ring gear 13 and the housing 9. When the second brake 62 is in the released state, it does not brake the rotation of the first ring gear 13, and the first ring gear 13 is rotatable.

[0096] Also in the multi-stage transmission 100 of the second embodiment configured as described above, similarly to FIG. 2, by selectively engaging the first to third clutches 51 to 53 and the first to third brakes 61 to 63 to regulate the rotation of the rotating elements of the first to fourth planetary gear sets 1 to 4, it is possible to realize gear ratios of 10 forward speeds and 2 reverse speeds. Also in the multi-stage transmission 100 of the second embodiment, the effect of reducing the variation in the step ratios of the multi-stage transmission 100 can be obtained in the same manner as in the first embodiment.

[0097] [Third Embodiment] FIG. 6 is a schematic diagram of a multi-stage transmission 100 according to the third embodiment. FIG. 7 is a table showing the tooth number ratios in each of the planetary gear sets 1 to 4 of the multi-stage transmission 100 according to the third embodiment. In the following description of the third embodiment, the description of the same configuration as in the first embodiment will be omitted, and the description will focus on the configuration specific to the third embodiment that is different from the first embodiment.

[0098] The multi-stage transmission 100 according to the third embodiment is different from the first embodiment in that, as shown in FIG. 7, four or fewer planetary gear sets 1 to 4 include at least one double pinion type planetary gear mechanism. Specifically, in the multi-stage transmission 100 according to the third embodiment, the second planetary gear set 2 is configured as a double pinion type planetary gear mechanism.

[0099] The second planetary gear 22 of the second planetary gear set 2 has an inner pinion gear and an outer pinion gear. The inner pinion gear meshes with the second sun gear 21. The outer pinion gear meshes with the second ring gear 23. The inner pinion gear and the outer pinion gear also mesh with each other. The inner pinion gear is arranged radially inwardly away from the second ring gear 23, and the outer pinion gear is arranged radially outwardly away from the second sun gear 21. The second planetary carrier 24 rotatably supports both the inner pinion gear and the outer pinion gear.

[0100] As shown in FIG. 6, the second planetary carrier 24 is configured to rotate integrally with the first intermediate coupling member 81. Specifically, the second planetary carrier 24 is fixed to the first intermediate coupling member 81. The second planetary carrier 24 and the first intermediate coupling member 81 may be formed by one member. The first intermediate coupling member 81 connects the first sun gear 11 of the first planetary gear set 1, the second planetary carrier 24 of the second planetary gear set 2, and the fourth sun gear 41 of the fourth planetary gear set 4. The first sun gear 11, the second planetary carrier 24, and the fourth sun gear 41 are configured to rotate integrally with each other.

[0101] The second ring gear 23 is configured to rotate integrally with the third intermediate coupling member 83. Specifically, the second ring gear 23 is fixed to the third intermediate coupling member 83. The second ring gear 23 and the third intermediate coupling member 83 may be formed by one member. The third intermediate coupling member 83 connects the second ring gear 23 of the second planetary gear set 2 and the third ring gear 33 of the third planetary gear set 3. The second ring gear 23 and the third ring gear 33 are configured to rotate integrally with each other.

[0102] The second clutch 52 is configured to selectively connect the third planetary carrier 34 to the first sun gear 11, the second planetary carrier 24, and the fourth sun gear 41.

[0103] When the second clutch 52 is engaged, it connects the third planetary carrier 34 to the first sun gear 11, the second planetary carrier 24, and the fourth sun gear 41 via the first intermediate coupling member 81. Therefore, the third planetary carrier 34, the first sun gear 11, the second planetary carrier 24, and the fourth sun gear 41 rotate integrally. When the second clutch 52 is disengaged, it releases the connection between the third planetary carrier 34 and the first intermediate coupling member 81. Therefore, the third planetary carrier 34 is rotatable relative to the first sun gear 11, the second planetary carrier 24, and the fourth sun gear 41.

[0104] Also in the multi-stage transmission 100 of the third embodiment configured as described above, similarly to FIG. 2, by selectively engaging the first to third clutches 51 to 53 and the first to third brakes 61 to 63 to restrict the rotation of the rotating elements of the first to fourth planetary gear sets 1 to 4, it is possible to realize gear ratios of 10 forward speeds and 2 reverse speeds. Also in the multi-stage transmission 100 of the third embodiment, the effect of reducing the variation in the step ratios of the multi-stage transmission 100 can be obtained in the same manner as in the first embodiment.

[0105] [Fourth Embodiment] FIG. 8 is a schematic diagram of a multi-stage transmission 100 according to the fourth embodiment. FIG. 9 is a table showing the tooth number ratios in each of the planetary gear sets 1 to 4 of the multi-stage transmission 100 according to the fourth embodiment. In the following description of the fourth embodiment, the description of the same configurations as those in the first embodiment will be omitted, and the description will focus on the configurations specific to the fourth embodiment that are different from those in the first embodiment.

[0106] The 4 multi-stage transmission 100 according to the embodiment is different from the first embodiment in that, as shown in FIG. 9, four or fewer planetary gear sets 1 to 4 include at least one double pinion type planetary gear mechanism. Specifically, in the multi-stage transmission 100 according to the fourth embodiment, the third planetary gear set 3 is configured as a double pinion type planetary gear mechanism.

[0107] The third planetary gear 32 of the third planetary gear set 3 has an inner pinion gear and an outer pinion gear. The inner pinion gear meshes with the third sun gear 31. The outer pinion gear meshes with the third ring gear 33. The inner pinion gear and the outer pinion gear also mesh with each other. The inner pinion gear is arranged radially inwardly away from the third ring gear 33, and the outer pinion gear is arranged radially outwardly away from the third sun gear 31. The third planetary carrier 34 rotatably supports both the inner pinion gear and the outer pinion gear.

[0108] As shown in FIG. 8, the third planetary carrier 34 is configured to rotate integrally with the third intermediate coupling member 83. Specifically, the third planetary carrier 34 is fixed to the third intermediate coupling member 83. The third planetary carrier 34 and the third intermediate coupling member 83 may be formed by one member. The third intermediate coupling member 83 connects the second planetary carrier 24 of the second planetary gear set 2 and the third planetary carrier 34 of the third planetary gear set 3. The second planetary carrier 24 and the third planetary carrier 34 are configured to rotate integrally with each other.

[0109] The second clutch 52 is configured to selectively connect the third ring gear 33 of the third planetary gear set 3 and the first intermediate coupling member 81. The second clutch 52 is configured to selectively connect the third ring gear 33 and the first sun gear 11, the second ring gear 23, and the fourth sun gear 41.

[0110] When the second clutch 52 is in the engaged state, it connects the third ring gear 33, the first sun gear 11, the second ring gear 23, and the fourth sun gear 41 via the first intermediate coupling member 81. Therefore, the third ring gear 33, the first sun gear 11, the second ring gear 23, and the fourth sun gear 41 rotate integrally. When the second clutch 52 is in the released state, it releases the connection between the third ring gear 33 and the first intermediate coupling member 81. Therefore, the third ring gear 33 is rotatable relative to the first sun gear 11, the second ring gear 23, and the fourth sun gear 41.

[0111] The third clutch 53 is configured to selectively connect the third ring gear 33 of the third planetary gear set 3 and the fourth intermediate coupling member 84. The third clutch 53 is configured to selectively connect the third ring gear 33 and the fourth planetary carrier 44 of the fourth planetary gear set 4.

[0112] When the third clutch 53 is in the engaged state, it connects the third ring gear 33 and the fourth intermediate coupling member 84. When the third clutch 53 is in the engaged state, it connects the third ring gear 33 and the fourth planetary carrier 44 via the fourth intermediate coupling member 84. Therefore, the third ring gear 33 and the fourth planetary carrier 44 rotate integrally. When the third clutch 53 is in the released state, it releases the connection between the third ring gear 33 and the fourth intermediate coupling member 84. Therefore, the third ring gear 33 and the fourth planetary carrier 44 are rotatable relative to each other.

[0113] Also in the multi-stage transmission 100 of the fourth embodiment configured as described above, similarly to FIG. 2, by selectively engaging the first to third clutches 51 to 53 and the first to third brakes 61 to 63 and restricting the rotation of the rotating elements of the first to fourth planetary gear sets 1 to 4, it is possible to realize gear ratios of 10 forward speeds and 2 reverse speeds. Also in the multi-stage transmission 100 of the fourth embodiment, the effect of reducing the variation in the step ratio of the multi-stage transmission 100 can be obtained in the same manner as in the first embodiment.

[0114] The multi-stage transmission 100 of the above-described embodiment can be used in any machine equipped with a multi-stage transmission, but is particularly applicable to construction machines and mining machines such as dump trucks.

[0115] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0116] 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, 61 First brake, 62 Second brake, 63 Third brake, 81 First intermediate coupling member, 82 Second intermediate coupling member, 83 Third intermediate coupling member, 84 Fourth intermediate coupling member, 100 Multi-stage transmission, O Axis of rotation.

Claims

1. An input member, an output member, a first planetary gear set, a second planetary gear set, a third planetary gear set, and a fourth planetary gear set that are arranged axially in order from the input member toward the output member, each planetary gear set including a sun gear, a planetary carrier, and a ring gear; four planetary gear sets; an intermediate coupling member that couples the sun gear of the first planetary gear set, the ring gear of the second planetary gear set, and the sun gear of the fourth planetary gear set; six control elements, each of the six control elements being operably coupled to at least one of the four planetary gear sets and being 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 two reverse gear ratios, One of the six control elements selectively couples the sun gear of the third planetary gear set and the planetary carrier of the fourth planetary gear set; A multi-stage transmission.

2. The input member is connected to the sun gear of the third planetary gear set. The multi-stage transmission according to claim 1.

3. The output member is connected to the ring gear of the fourth planetary gear set. The multi-stage transmission according to claim 2.

4. Another one of the six control elements brakes the rotation of the planetary carrier of the fourth planetary gear set. The multi-stage transmission according to claim 3.

5. Another one of the six control elements selectively couples the planetary carrier of the third planetary gear set and the intermediate coupling member. The multi-stage transmission according to claim 1.

6. Another one of the six control elements brakes the rotation of the ring gear of the first planetary gear set and the sun gear of the second planetary gear set. The multi-stage transmission according to claim 3.

7. The multi-stage transmission according to claim 3, further comprising another intermediate coupling member that couples the planetary carrier of the second planetary gear set and the ring gear of the third planetary gear set.

8. An input member, an output member, A four - planetary - gear set including a first planetary - gear set, a second planetary - gear set, a third planetary - gear set, and a fourth planetary - gear set, which are arranged axially in order from the input member toward the output member, and each planetary - gear set includes a sun gear, a planetary carrier, and a ring gear; An intermediate coupling member connecting the sun gear of the first planetary - gear set, the ring gear of the second planetary - gear set, and the sun gear of the fourth planetary - gear set; Six control elements; Each of the six control elements is operably coupled to at least one of the four planetary - gear sets and is selectively engageable to produce a set of different gear ratios between the input member and the output member; The input member is connected to the sun gear of the third planetary - gear set; The output member is connected to the ring gear of the fourth planetary - gear set; A first control element of the six control elements selectively connects the sun gear of the third planetary - gear set and the planetary carrier of the fourth planetary - gear set; A second control element of the six control elements brakes the rotation of the planetary carrier of the fourth planetary - gear set, a multi - speed transmission. **Claim 9** An input member; An output member; A first planetary - gear set having a first sun gear, a first planetary gear, a first ring gear, and a first planetary carrier; A second planetary - gear set having a second sun gear, a second planetary gear, a second ring gear, and a second planetary carrier; A third planetary - gear set having a third sun gear, a third planetary gear, a third ring gear, and a third planetary carrier, which is connected to the input member; A fourth planetary - gear set having a fourth sun gear, a fourth planetary gear, a fourth ring gear connected to the output member, and a fourth planetary carrier; A first intermediate coupling member connecting the first sun gear, the second ring gear, and the fourth sun gear; A second intermediate coupling member connecting the first ring gear and the second sun gear; A third intermediate coupling member connecting the second planetary carrier and the third ring gear; A first clutch selectively connecting the third sun gear and the fourth planetary carrier; A second clutch selectively connecting the third planetary carrier and the first intermediate coupling member; A third clutch selectively connecting the third planetary carrier and the fourth planetary carrier; a first brake that brakes the rotation of the second intermediate coupling member; a second brake that brakes the rotation of the first planetary carrier; a third brake that brakes the rotation of the fourth planetary carrier, and a multi-stage transmission.

Images