Method and system for controlling transmission

Abstract

To reduce a shift shock of a transmission.SOLUTION: A method according to the present disclosure comprises: starting the supply of hydraulic oil to a second clutch; maintaining the oil pressure of the second clutch at a predetermined low pressure state after completion of filling of the hydraulic oil into the second clutch; starting the supply of hydraulic oil to a first clutch after completion of filling of the hydraulic oil into the second clutch; starting the supply of hydraulic oil to an input clutch after completion of filling of the hydraulic oil into the second clutch; and increasing the oil pressure of the second clutch from the low pressure state to engage the second clutch after the first clutch and the input clutch are engaged with each other.SELECTED DRAWING: Figure 22

Description

[Technical Field]

[0001] The present disclosure relates to methods and systems for controlling a transmission. [Background technology]

[0002] Some transmissions include multiple transmission shafts, including an input shaft, an output shaft, and an intermediate shaft disposed between the input shaft and the output shaft in a power transmission path. For example, the transmission disclosed in Patent Document 1 includes an input shaft, a first intermediate shaft, a second intermediate shaft, an output shaft, and multiple gears and clutches connecting these shafts. In this transmission, the rotation of the input shaft is transmitted to the first intermediate shaft by engaging any one of the clutches (16, 18) disposed on the input shaft. The rotation of the first intermediate shaft is transmitted to the second intermediate shaft by engaging any one of the clutches (24, 28) disposed on the first intermediate shaft. Then, the rotation of the second intermediate shaft is transmitted to the output shaft by engaging any one of the clutches (41, 43) disposed on the output shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 4,589,295 Summary of the Invention [Problem to be solved by the invention]

[0004] When multiple clutches are switched during a gear shift in the transmission as described above, the changes in rotational speed of the multiple clutches are transmitted to the output shaft, causing a large gear shift shock. An object of the present disclosure is to reduce the gear shift shock in the transmission. [Means for solving the problem]

[0005] A method according to a first aspect of the present disclosure is a method for controlling a transmission. The transmission includes a first transmission shaft, a second transmission shaft, an input shaft, an output shaft, an input clutch, a first clutch, and a second clutch. The second transmission shaft is disposed downstream of the first transmission shaft in a power transmission path. The input shaft is disposed upstream of the first transmission shaft. The output shaft is disposed downstream of the second transmission shaft in the transmission path. The input clutch transmits rotation of the input shaft to the first transmission shaft in an engaged state. The first clutch transmits rotation of the first transmission shaft to the second transmission shaft in an engaged state. The second clutch transmits rotation of the second transmission shaft to the output shaft in an engaged state. The method according to this aspect includes starting the supply of hydraulic oil to the second clutch, maintaining the hydraulic pressure of the second clutch at a predetermined low pressure state after the filling of hydraulic oil into the second clutch is completed, starting the supply of hydraulic oil to the first clutch after the filling of hydraulic oil into the second clutch is completed, starting the supply of hydraulic oil to the input clutch after the filling of hydraulic oil into the second clutch is completed, and increasing the hydraulic pressure of the second clutch from the low pressure state to engage the second clutch after the first clutch and the input clutch are engaged.

[0006] A method according to a second aspect of the present disclosure is a method for controlling a transmission. The transmission includes a plurality of transmission shafts and a plurality of clutches. The plurality of transmission shafts includes an input shaft, an output shaft, and an intermediate shaft disposed between the input shaft and the output shaft in a driving force transmission path. The plurality of clutches connect the plurality of transmission shafts in an engaged state, respectively, and transmit rotation of an upstream transmission shaft to a downstream transmission shaft. The plurality of clutches includes a most downstream clutch, and a first other clutch and a second other clutch disposed upstream of the most downstream clutch. The method according to this aspect includes starting the supply of hydraulic oil to the most downstream clutch among a plurality of clutches to be engaged; after completing the filling of hydraulic oil into the most downstream clutch, maintaining the hydraulic pressure of the most downstream clutch at a predetermined low pressure state; after completing the filling of hydraulic oil into the most downstream clutch, starting the supply of hydraulic oil to a first other clutch; after completing the filling of hydraulic oil into the most downstream clutch, starting the supply of hydraulic oil to a second other clutch; and after the first other clutch and the second other clutch are engaged, increasing the hydraulic pressure of the most downstream clutch from the low pressure state to engage the most downstream clutch.

[0007] A system according to a third aspect of the present disclosure is a system for controlling a transmission. The transmission includes a first transmission shaft, a second transmission shaft, an input shaft, an output shaft, an input clutch, a first clutch, and a second clutch. The second transmission shaft is disposed downstream of the first transmission shaft in a power transmission path. The input shaft is disposed upstream of the first transmission shaft. The output shaft is disposed downstream of the second transmission shaft in the transmission path. The input clutch transmits rotation of the input shaft to the first transmission shaft in an engaged state. The first clutch transmits rotation of the first transmission shaft to the second transmission shaft in an engaged state. The second clutch transmits rotation of the second transmission shaft to the output shaft in an engaged state. The system according to this aspect includes a sensor and a controller. The sensor detects completion of filling of hydraulic oil to the second clutch. The controller controls supply of hydraulic oil to the first clutch and the second clutch. The controller controls supply of hydraulic oil to the first clutch and the second clutch. The controller starts supply of hydraulic oil to the second clutch. The controller maintains the hydraulic pressure of the second clutch at a predetermined low pressure state after the filling of hydraulic oil into the second clutch is completed. The controller starts the supply of hydraulic oil to the first clutch after the filling of hydraulic oil into the second clutch is completed. The controller starts the supply of hydraulic oil to the input clutch after the filling of hydraulic oil into the second clutch is completed. After the first clutch and the input clutch are engaged, the controller increases the hydraulic pressure of the second clutch from a low pressure state to engage the second clutch. [Effects of the Invention]

[0008] According to the present disclosure, after the most downstream clutch has been filled with hydraulic oil, the supply of hydraulic oil to the other clutches begins, and the most downstream clutch is engaged after the other clutches are engaged. This prevents changes in rotational speed that occur when the other clutches are engaged from being transmitted to the output shaft, thereby reducing gear shift shock in the transmission. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a side view of a work machine according to an embodiment. [Figure 2] FIG. 2 is a skeleton diagram showing the configuration of a transmission. [Figure 3] FIG. 2 is a diagram illustrating the arrangement of transmission shafts and gears as viewed from the axial direction of each transmission shaft of the transmission. [Figure 4] 1 is a schematic diagram showing the configuration of a control system for a transmission mounted on a work machine. [Figure 5] 10 is a table showing the engaged and disengaged states of a plurality of clutches at each speed stage. [Figure 6] FIG. 2 is a diagram showing a transmission path of driving force in a first forward speed in the transmission. [Figure 7] FIG. 4 is a diagram showing a transmission path of driving force in second forward speed in the transmission. [Figure 8] FIG. 4 is a diagram showing a transmission path of driving force in third forward speed in the transmission. [Figure 9] FIG. 4 is a diagram showing a driving force transmission path in the fourth forward speed in the transmission. [Figure 10] FIG. 2 is a diagram showing a transmission path of driving force in the fifth forward speed in the transmission. [Figure 11] FIG. 2 is a diagram showing a driving force transmission path in the sixth forward speed in the transmission. [Figure 12] FIG. 2 is a diagram showing a transmission path of driving force in seventh forward speed in the transmission. [Figure 13] FIG. 2 is a diagram showing the transmission path of driving force in eighth forward speed in the transmission. [Figure 14] FIG. 4 is a diagram showing a transmission path of driving force in first reverse gear in the transmission. [Figure 15] FIG. 4 is a diagram showing a transmission path of driving force in second reverse gear in the transmission. [Figure 16] FIG. 4 is a diagram showing a driving force transmission path in the third reverse gear in the transmission. [Figure 17] FIG. 4 is a diagram showing a driving force transmission path in the fourth reverse gear in the transmission. [Figure 18] FIG. 4 is a diagram showing a driving force transmission path in the fifth reverse gear in the transmission. [Figure 19] FIG. 2 is a diagram showing a driving force transmission path in the sixth reverse gear in the transmission. [Figure 20] FIG. 10 is a diagram showing the transmission path of driving force in the seventh reverse gear in the transmission. [Figure 21] FIG. 2 is a diagram showing the transmission path of driving force in eighth reverse gear in the transmission. [Figure 22] 5 is a timing chart showing the control of the clutch oil pressure when the transmission speed is changed. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will now be described with reference to the drawings. Fig. 1 is a side view of a work machine 1 according to the embodiment. The work machine 1 according to the embodiment is a motor grader. As shown in Fig. 1, the work machine 1 includes a body 2, running wheels 3A, 4A, 4B, and a work implement 9. The body 2 includes a front frame 11, a rear frame 12, a cab 13, and a power compartment 14. The running wheels 3A, 4A, 4B include a front wheel 3A and rear wheels 4A, 4B. Note that the running wheels 3A, 4A, 4B are provided on the left and right, respectively, but Fig. 1 shows only the left front wheel 3A and rear wheels 4A, 4B.

[0011] The rear frame 12 is connected to the front frame 11. The front frame 11 can be articulated left and right relative to the rear frame 12. A cab 13 and a power compartment 14 are disposed on the rear frame 12. A driver's seat is disposed inside the cab 13. The power compartment 14 is disposed behind the cab 13. The front frame 11 extends forward from the rear frame 12. A front wheel 3A is attached to the front frame 11. Rear wheels 4A, 4B are attached to the rear frame 12.

[0012] The work implement 9 is movably connected to the vehicle body 2. The work implement 9 includes a support member 15 and a blade 16. The blade 16 is disposed between the front wheels 3A and the rear wheels 4A. The blade is disposed below the front frame 11. The support member 15 is movably connected to the vehicle body 2. The support member 15 supports the blade 16.

[0013] The work machine 1 is equipped with an engine 5, a torque converter 6, a transmission 7, and a drive shaft 8. The torque converter 6 is connected to the engine 5. The transmission 7 is connected to the engine 5 via the torque converter 6. The drive shaft 8 is connected to the transmission 7. The transmission 7 changes the speed of the driving force from the engine 5 and transmits it to the rear wheels 4A, 4B. The transmission 7 transmits the driving force from the engine 5 to the rear wheels 4A, 4B via the drive shaft 8 and an axle (not shown).

[0014] FIG. 2 is a skeleton diagram showing the configuration of the transmission 7. FIG. 3 is a diagram showing the arrangement of the transmission shafts and gears of the transmission 7 as viewed from the axial direction of each transmission shaft. The transmission 7 according to this embodiment has eight forward speeds and eight reverse speeds. As shown in FIGS. 2 and 3, the transmission 7 includes an input shaft 20, a reversing shaft 30, a first intermediate shaft 40, a second intermediate shaft 50, and an output shaft 60.

[0015] The input shaft 20 is connected to the engine 5 via a torque converter 6. The counter-rotating shaft 30, the first intermediate shaft 40, and the second intermediate shaft 50 are arranged between the input shaft 20 and the output shaft 60 in a driving force transmission path. The counter-rotating shaft 30 is arranged downstream of the input shaft 20 in the transmission path. The first intermediate shaft 40 is arranged downstream of the input shaft 20 in the transmission path. The second intermediate shaft 50 is arranged downstream of the first intermediate shaft 40 in the transmission path. The output shaft 60 is arranged downstream of the second intermediate shaft 50 in the transmission path. The output shaft 60 is connected to the drive shaft 8.

[0016] The input shaft 20, the reversing shaft 30, the first intermediate shaft 40, the second intermediate shaft 50, and the output shaft 60 are arranged parallel to one another. As shown in Fig. 3, the reversing shaft 30 is arranged below the input shaft 20. The reversing shaft 30 is arranged offset in the left-right direction from the input shaft 20. The left-right direction refers to the axial direction of each of the transmission shafts 20, 30, 40, 50, and 60 and the direction perpendicular to the up-down direction.

[0017] The first intermediate shaft 40 is disposed below the input shaft 20. The first intermediate shaft 40 is disposed below the reversing shaft 30. The first intermediate shaft 40 is disposed offset in the left-right direction from the input shaft 20 and the reversing shaft 30. The second intermediate shaft 50 is disposed below the first intermediate shaft 40. The second intermediate shaft 50 is disposed offset in the left-right direction from the first intermediate shaft 40. The second intermediate shaft 50 is disposed offset in the left-right direction from the reversing shaft 30. The output shaft 60 is disposed below the second intermediate shaft 50. The output shaft 60 is disposed directly below the input shaft 20. The output shaft 60 is disposed offset in the left-right direction from the second intermediate shaft 50.

[0018] The transmission 7 includes an input gear 21, an input low idler gear 22, an input high idler gear 23, an input low clutch 24, and an input high clutch 25. The input gear 21, the input low idler gear 22, the input high idler gear 23, the input low clutch 24, and the input high clutch 25 are arranged on an input shaft 20. The input gear 21 is fixed to the input shaft 20. The input low idler gear 22 and the input high idler gear 23 are capable of idling relative to the input shaft 20. The input low clutch 24, in an engaged state, engages the input low idler gear 22 with the input shaft 20. The input high clutch 25, in an engaged state, engages the input high idler gear 23 with the input shaft 20.

[0019] The transmission 7 includes a reverse gear 31, a reverse low idler gear 32, a reverse high idler gear 33, a reverse low clutch 34, and a reverse high clutch 35. The reverse gear 31, the reverse low idler gear 32, the reverse high idler gear 33, the reverse low clutch 34, and the reverse high clutch 35 are arranged on a reversing shaft 30. The reverse gear 31 is fixed to the reversing shaft 30. The reverse gear 31 meshes with the input gear 21. As a result, the reversing shaft 30 constantly rotates in the opposite direction to the input shaft 20 in response to the rotation of the input shaft 20. The reverse low idler gear 32 and the reverse high idler gear 33 can rotate freely relative to the reversing shaft 30. The reversing low idler gear 32 meshes with a first low fixed gear 41. The reversing high idler gear 33 meshes with a first high fixed gear 42. When engaged, the reversing low clutch 34 engages the reversing low idler gear 32 with the reversing shaft 30. When the reverse high clutch 35 is engaged, it engages the reverse high idler gear 33 with the reverse shaft 30 .

[0020] The transmission 7 includes a first low fixed gear 41, a first high fixed gear 42, a first low idler gear 43, a first high idler gear 44, a first low clutch 45, and a first high clutch 46. The first low fixed gear 41, the first high fixed gear 42, the first low idler gear 43, the first high idler gear 44, the first low clutch 45, and the first high clutch 46 are arranged on a first intermediate shaft 40. The first low fixed gear 41 and the first high fixed gear 42 are fixed to the first intermediate shaft 40. The first low fixed gear 41 meshes with the input low idler gear 22 and the counter low idler gear 32. The first high fixed gear 42 meshes with the input high idler gear 23 and the counter high idler gear 33. The first low idler gear 43 and the first high idler gear 44 are capable of idling with respect to the first intermediate shaft 40. In an engaged state, the first low clutch 45 engages the first low idler gear 43 with the first intermediate shaft 40. In an engaged state, the first high clutch 46 engages the first high idler gear 44 with the first intermediate shaft 40.

[0021] The transmission 7 includes a second low fixed gear 51, a second high fixed gear 52, a second low idler gear 53, a second high idler gear 54, a second low clutch 55, and a second high clutch 56. The second low fixed gear 51, the second high fixed gear 52, the second low idler gear 53, the second high idler gear 54, the second low clutch 55, and the second high clutch 56 are arranged on a second intermediate shaft 50. The second low fixed gear 51 and the second high fixed gear 52 are fixed to the second intermediate shaft 50. The second low fixed gear 51 meshes with the first low idler gear 43. The second high fixed gear 52 meshes with the first high idler gear 44. The second low idler gear 53 and the second high idler gear 54 are capable of idling relative to the second intermediate shaft 50. In an engaged state, the second low clutch 55 engages the second low idler gear 53 with the second intermediate shaft 50. In an engaged state, the second high clutch 56 engages the second high idler gear 54 with the second intermediate shaft 50.

[0022] The transmission 7 includes an output low fixed gear 61 and an output high fixed gear 62. The output low fixed gear 61 and the output high fixed gear 62 are arranged on an output shaft 60. The output low fixed gear 61 and the output high fixed gear 62 are fixed to the output shaft 60. The output low fixed gear 61 meshes with the second low idler gear 53. The output high fixed gear 62 meshes with the second high idler gear 54. No clutch is arranged on the output shaft 60.

[0023] Fig. 4 is a schematic diagram showing the configuration of a control system for the transmission 7 mounted on the work machine 1. As shown in Fig. 4, the work machine 1 is equipped with a shift operating device 71, a control valve 72, a controller 73, and filling sensors S1-S8. The shift operating device 71 can be operated by an operator to change the gear position of the transmission 7. The shift operating device 71 includes, for example, a shift lever.

[0024] The control valve 72 includes a plurality of valves corresponding to the plurality of clutches 24, 25, 34, 35, 45, 46, 55, and 56. The control valve 72 controls the flow rate of hydraulic oil supplied to the plurality of clutches 24, 25, 34, 35, 45, 46, 55, and 56 of the transmission 7 in response to a command signal from the controller 73. The plurality of clutches 24, 25, 34, 35, 45, 46, 55, and 56 are hydraulic clutches that are switched between a disengaged state and an engaged state in response to the hydraulic pressure of the supplied hydraulic oil.

[0025] The filling sensors S1-S8 detect the completion of filling of hydraulic oil into the clutches 24, 25, 34, 35, 45, 46, 55, and 56. The filling sensors S1-S8 are, for example, switches that operate when hydraulic oil is filled into the oil chambers of the clutches 24, 25, 34, 35, 45, 46, 55, and 56. Alternatively, the filling sensors S1-S8 may be, for example, pressure sensors that detect the oil pressure in the oil chambers of the clutches 24, 25, 34, 35, 45, 46, 55, and 56.

[0026] The controller 73 controls the control valve 72 to control the hydraulic pressure of each of the clutches 24, 25, 34, 35, 45, 46, 55, and 56. In this way, the controller 73 switches the gear stage of the transmission 7 in accordance with the operation of the shift operating device 71 by switching each of the multiple clutches 24, 25, 34, 35, 45, 46, 55, and 56 between an engaged state and a disengaged state. Alternatively, the controller 73 may automatically switch the gear stage of the transmission 7 based on the vehicle speed or engine rotation speed, without depending on the operation of the shift operating device 71.

[0027] FIG. 5 is a table showing the engaged and disengaged states of multiple clutches 24, 25, 34, 35, 45, 46, 55, and 56 at each speed stage. In FIG. 5, F1 to F8 indicate forward speed stages 1 to 8. R1 to R8 indicate reverse speed stages 1 to 8. FL indicates the input low clutch 24. FH indicates the input high clutch 25. RL indicates the reversing low clutch 34. RH indicates the reversing high clutch 35. 1L indicates the first low clutch 45. 1H indicates the first high clutch 46. 2L indicates the second low clutch 55. 2H indicates the second high clutch 56. The circles in each column of FIG. 5 indicate the engaged state. The blank columns indicate the disengaged state.

[0028] As shown in Fig. 5, when the speed stage of the transmission 7 is set to the first forward speed, the controller 73 engages the input low clutch 24, the first low clutch 45, and the second low clutch 55, and disengages the other clutches. As a result, as shown in Fig. 6, the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input low clutch 24, the input low idler gear 22, the first low fixed gear 41, the first intermediate shaft 40, the first low clutch 45, the first low idler gear 43, the second low fixed gear 51, the second intermediate shaft 50, the second low clutch 55, the second low idler gear 53, and the output low fixed gear 61.

[0029] When the speed stage of the transmission 7 is set to second forward speed, the controller 73 engages the input high clutch 25, the first low clutch 45, and the second low clutch 55, and disengages the other clutches. As a result, as shown in Fig. 7 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input high clutch 25, the input high idler gear 23, the first high fixed gear 42, the first intermediate shaft 40, the first low clutch 45, the first low idler gear 43, the second low fixed gear 51, the second intermediate shaft 50, the second low clutch 55, the second low idler gear 53, and the output low fixed gear 61.

[0030] When the speed stage of the transmission 7 is set to the third forward speed, the controller 73 engages the input low clutch 24, the first high clutch 46, and the second low clutch 55, and disengages the other clutches. As a result, as shown in Fig. 8 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input low clutch 24, the input low idler gear 22, the first low fixed gear 41, the first intermediate shaft 40, the first high clutch 46, the first high idler gear 44, the second high fixed gear 52, the second intermediate shaft 50, the second low clutch 55, the second low idler gear 53, and the output low fixed gear 61.

[0031] When the speed stage of the transmission 7 is set to fourth forward speed, the controller 73 engages the input high clutch 25, the first high clutch 46, and the second low clutch 55, and disengages the other clutches. As a result, as shown in Fig. 9 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input high clutch 25, the input high idler gear 23, the first high fixed gear 42, the first intermediate shaft 40, the first high clutch 46, the first high idler gear 44, the second high fixed gear 52, the second intermediate shaft 50, the second low clutch 55, the second low idler gear 53, and the output low fixed gear 61.

[0032] When the speed stage of the transmission 7 is set to the fifth forward speed, the controller 73 engages the input low clutch 24, the first low clutch 45, and the second high clutch 56, and disengages the other clutches. As a result, as shown in Fig. 10 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input low clutch 24, the input low idler gear 22, the first low fixed gear 41, the first intermediate shaft 40, the first low clutch 45, the first low idler gear 43, the second low fixed gear 51, the second intermediate shaft 50, the second high clutch 56, the second high idler gear 54, and the output high fixed gear 62.

[0033] When the gear position of the transmission 7 is set to sixth forward speed, the controller 73 engages the input high clutch 25, the first low clutch 45, and the second high clutch 56, and disengages the other clutches. As a result, as shown in Fig. 11 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input high clutch 25, the input high idler gear 23, the first high fixed gear 42, the first intermediate shaft 40, the first low clutch 45, the first low idler gear 43, the second low fixed gear 51, the second intermediate shaft 50, the second high clutch 56, the second high idler gear 54, and the output high fixed gear 62.

[0034] When the speed stage of the transmission 7 is set to the seventh forward speed, the controller 73 engages the input low clutch 24, the first high clutch 46, and the second high clutch 56, and disengages the other clutches. As a result, as shown in Fig. 12 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input low clutch 24, the input low idler gear 22, the first low fixed gear 41, the first intermediate shaft 40, the first high clutch 46, the first high idler gear 44, the second high fixed gear 52, the second intermediate shaft 50, the second high clutch 56, the second high idler gear 54, and the output high fixed gear 62.

[0035] When the gear position of the transmission 7 is set to eighth forward speed, the controller 73 engages the input high clutch 25, the first high clutch 46, and the second high clutch 56, and disengages the other clutches. As a result, as shown in Fig. 13 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input high clutch 25, the input high idler gear 23, the first high fixed gear 42, the first intermediate shaft 40, the first high clutch 46, the first high idler gear 44, the second high fixed gear 52, the second intermediate shaft 50, the second high clutch 56, the second high idler gear 54, and the output high fixed gear 62.

[0036] When the speed stage of the transmission 7 is set to first reverse speed, the controller 73 engages the reverse low clutch 34, the first low clutch 45, and the second low clutch 55, and disengages the other clutches. As a result, as shown in Fig. 14 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input gear 21, the reverse gear 31, the reverse shaft 30, the reverse low clutch 34, the reverse low idler gear 32, the first low fixed gear 41, the first intermediate shaft 40, the first low clutch 45, the first low idler gear 43, the second low fixed gear 51, the second intermediate shaft 50, the second low clutch 55, the second low idler gear 53, and the output low fixed gear 61.

[0037] When the speed stage of the transmission 7 is set to second reverse speed, the controller 73 engages the reverse high clutch 35, the first low clutch 45, and the second low clutch 55, and disengages the other clutches. As a result, as shown in Fig. 15 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input gear 21, the reverse gear 31, the reverse shaft 30, the reverse high clutch 35, the reverse high idler gear 33, the first high fixed gear 42, the first intermediate shaft 40, the first low clutch 45, the first low idler gear 43, the second low fixed gear 51, the second intermediate shaft 50, the second low clutch 55, the second low idler gear 53, and the output low fixed gear 61.

[0038] When the speed stage of the transmission 7 is set to third reverse speed, the controller 73 engages the reverse low clutch 34, the first high clutch 46, and the second low clutch 55, and disengages the other clutches. As a result, as shown in Fig. 16 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input gear 21, the reverse gear 31, the reverse shaft 30, the reverse low clutch 34, the reverse low idler gear 32, the first low fixed gear 41, the first intermediate shaft 40, the first high clutch 46, the first high idler gear 44, the second high fixed gear 52, the second intermediate shaft 50, the second low clutch 55, the second low idler gear 53, and the output low fixed gear 61.

[0039] When the speed stage of the transmission 7 is set to fourth reverse speed, the controller 73 engages the reverse high clutch 35, the first high clutch 46, and the second low clutch 55, and disengages the other clutches. As a result, as shown in Fig. 17 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input gear 21, the reverse gear 31, the reverse shaft 30, the reverse high clutch 35, the reverse high idler gear 33, the first high fixed gear 42, the first intermediate shaft 40, the first high clutch 46, the first high idler gear 44, the second high fixed gear 52, the second intermediate shaft 50, the second low clutch 55, the second low idler gear 53, and the output low fixed gear 61.

[0040] When the speed stage of the transmission 7 is set to the fifth reverse speed, the controller 73 engages the reverse low clutch 34, the first low clutch 45, and the second high clutch 56, and disengages the other clutches. As a result, as shown in Fig. 18 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input gear 21, the reverse gear 31, the reverse shaft 30, the reverse low clutch 34, the reverse low idler gear 32, the first low fixed gear 41, the first intermediate shaft 40, the first low clutch 45, the first low idler gear 43, the second low fixed gear 51, the second intermediate shaft 50, the second high clutch 56, the second high idler gear 54, and the output high fixed gear 62.

[0041] When the gear position of the transmission 7 is set to sixth reverse speed, the controller 73 engages the reverse high clutch 35, the first low clutch 45, and the second high clutch 56, and disengages the other clutches. As a result, as shown in Fig. 19 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input gear 21, the reverse gear 31, the reverse shaft 30, the reverse high clutch 35, the reverse high idler gear 33, the first high fixed gear 42, the first intermediate shaft 40, the first low clutch 45, the first low idler gear 43, the second low fixed gear 51, the second intermediate shaft 50, the second high clutch 56, the second high idler gear 54, and the output high fixed gear 62.

[0042] When the speed stage of the transmission 7 is set to the seventh reverse speed, the controller 73 engages the reverse low clutch 34, the first high clutch 46, and the second high clutch 56, and disengages the other clutches. As a result, as shown in Fig. 20 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input gear 21, the reverse gear 31, the reverse shaft 30, the reverse low clutch 34, the reverse low idler gear 32, the first low fixed gear 41, the first intermediate shaft 40, the first high clutch 46, the first high idler gear 44, the second high fixed gear 52, the second intermediate shaft 50, the second high clutch 56, the second high idler gear 54, and the output high fixed gear 62.

[0043] When the gear position of the transmission 7 is set to eighth reverse speed, the controller 73 engages the reverse high clutch 35, the first high clutch 46, and the second high clutch 56, and disengages the other clutches. As a result, as shown in Fig. 21 , the driving force from the engine 5 is transmitted from the input shaft 20 to the output shaft 60 via the input gear 21, the reverse gear 31, the reverse shaft 30, the reverse high clutch 35, the reverse high idler gear 33, the first high fixed gear 42, the first intermediate shaft 40, the first high clutch 46, the first high idler gear 44, the second high fixed gear 52, the second intermediate shaft 50, the second high clutch 56, the second high idler gear 54, and the output high fixed gear 62.

[0044] Next, the control of the hydraulic pressure of each of the clutches 24, 25, 34, 35, 45, 46, 55, and 56 when the speed stage of the transmission 7 is changed as described above will be described. Figure 22 is a timing chart showing the control of the hydraulic pressure of each of the clutches 24, 25, 34, 35, 45, 46, 55, and 56 when the speed stage of the transmission 7 is changed. In Figure 22, the vertical axis represents the command hydraulic pressure to each of the clutches 24, 25, 34, 35, 45, 46, 55, and 56, and the horizontal axis represents time.

[0045] In FIG. 22, the input clutch (engaged) refers to the clutch between the input low clutch 24 and the input high clutch 25 that can be switched from a disengaged state to an engaged state. The input clutch (released) refers to the clutch between the input low clutch 24 and the input high clutch 25 that can be switched from an engaged state to a disengaged state. The first clutch (engaged) refers to the clutch between the first low clutch 45 and the first high clutch 46 that can be switched from a disengaged state to an engaged state. The first clutch (released) refers to the clutch between the first low clutch 45 and the first high clutch 46 that can be switched from an engaged state to a disengaged state. The second clutch (engaged) refers to the clutch between the second low clutch 55 and the second high clutch 56 that can be switched from a disengaged state to an engaged state. The second clutch (released) refers to the clutch between the second low clutch 55 and the second high clutch 56 that can be switched from an engaged state to a disengaged state.

[0046] As shown in Figure 22, at time T0, the hydraulic pressure of the input clutch (released), first clutch (released), and second clutch (released) is maintained at first holding pressure P0 and they are in an engaged state. No hydraulic oil is supplied to the input clutch (engaged), first clutch (engaged), and second clutch (engaged), and they are in a disengaged state.

[0047] At time T1, the controller 73 starts supplying hydraulic oil to the second clutch (engagement) and reduces the hydraulic pressure of the second clutch (release) from the first holding pressure P0 to the crossover pressure P3. The controller 73 also reduces the hydraulic pressure of the input clutch (release) and the first clutch (release) from the first holding pressure P0 to the crossover pressure P3. Thereafter, the controller 73 maintains the hydraulic pressure of the second clutch (engagement) at the trigger pressure P1 for a predetermined trigger time. This allows the second clutch (engagement) to be filled with hydraulic oil. After the trigger time has elapsed, the controller 73 reduces the hydraulic pressure of the second clutch (engagement) from the trigger pressure P1.

[0048] At time T2, when filling sensors S7 and S8 detect the completion of filling of hydraulic oil to the second clutch (engaged), from time T2 onward, controller 73 maintains the hydraulic pressure of the second clutch (engaged) at second holding pressure P2 and reduces the hydraulic pressure of the second clutch (disengaged) from crossover pressure P3. As a result, the hydraulic pressure of the second clutch (engaged) is maintained at a low pressure, and the second clutch (engaged) is maintained in a slipping state. In addition, the second clutch (disengaged) is disengaged.

[0049] Furthermore, at time T2, when filling of hydraulic oil into the second clutch (engagement) is completed, the controller 73 starts supplying hydraulic oil to the input clutch (engagement) and maintains the hydraulic pressure of the input clutch (engagement) at trigger pressure P1 for a predetermined trigger time. This allows hydraulic oil to be filled into the input clutch (engagement). After the trigger time has elapsed, the controller 73 reduces the hydraulic pressure of the input clutch (engagement) from trigger pressure P1.

[0050] At time T3, when the filling sensors S1 and S2 detect the completion of filling of hydraulic oil into the input clutch (engaged), after time T3, the controller 73 increases the oil pressure of the input clutch (engaged) and reduces the oil pressure of the input clutch (released) from crossover pressure P3, thereby disengaging the input clutch (released) and engaging the input clutch (engaged).

[0051] Furthermore, at time T3, when filling of hydraulic oil to the input clutch (engagement) is completed, the controller 73 starts supplying hydraulic oil to the first clutch (engagement) and maintains the hydraulic pressure of the first clutch (engagement) at trigger pressure P1 for a predetermined trigger time. This completes filling of hydraulic oil to the first clutch (engagement). After the trigger time has elapsed, the controller 73 reduces the hydraulic pressure of the first clutch (engagement) from trigger pressure P1.

[0052] At time T4, when filling sensors S5 and S6 detect the completion of filling of hydraulic oil into the first clutch (engaged), after time T4, controller 73 increases the hydraulic pressure of the first clutch (engaged) and reduces the hydraulic pressure of the first clutch (released) from crossover pressure P3, thereby disengaging the first clutch (released) and engaging the first clutch (engaged).

[0053] After the input clutch (engagement) is engaged at time T5, the controller 73 further increases the oil pressure of the input clutch (engagement) to maintain it at the third holding pressure P4. After the first clutch (engagement) is engaged at time T6, the controller 73 further increases the oil pressure of the first clutch (engagement) to maintain it at the third holding pressure P4.

[0054] Furthermore, after the input clutch (engagement) and the first clutch (engagement) are engaged, the controller 73 increases the oil pressure of the second clutch (engagement) from the second holding pressure P2 to engage the second clutch (engagement). After the second clutch (engagement) is engaged at time T7, the controller 73 further increases the oil pressure of the second clutch (engagement) to maintain it at the third holding pressure P4.

[0055] The above describes the case where the input low clutch 24 and the input high clutch 25 are switched, but when the reverse low clutch 34 and the reverse high clutch 35 are switched, the oil pressure to the reverse low clutch 34 and the reverse high clutch 35 is controlled in the same way as the input low clutch 24 and the input high clutch 25.

[0056] In the system according to the present embodiment described above, after the filling of hydraulic oil into the second clutch (engaged), which is the most downstream, is completed, the supply of hydraulic oil to the input clutch (engaged) and the first clutch (engaged) is started, and after the input clutch (engaged) and the first clutch (engaged) are engaged, the second clutch (engaged) is engaged. Therefore, the change in rotational speed when the input clutch (engaged) and the first clutch (engaged) are engaged is prevented from being transmitted to the output shaft 60. This reduces gear shift shock in the transmission 7.

[0057] Furthermore, the supply of hydraulic oil to the input clutch (engaged) and the first clutch (engaged) starts at different times, which reduces the load on the hydraulic pump that supplies hydraulic oil to the input clutch (engaged) and the first clutch (engaged).

[0058] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0059] The work machine 1 is not limited to a motor grader, but may be another machine such as a wheel loader. The configuration of the transmission 7 is not limited to that in the above embodiment, and may be modified. For example, in the above embodiment, when the driving force is transmitted via the reversing shaft 30, the work machine 1 moves backward. However, when the driving force is transmitted via the reversing shaft 30, the work machine 1 may also move forward.

[0060] In the above embodiment, the supply of hydraulic oil to the input clutch (engaged) is started after the supply of hydraulic oil to the first clutch (engaged) is started. However, conversely, the supply of hydraulic oil to the input clutch (engaged) may be started after the supply of hydraulic oil to the first clutch (engaged) is started. Alternatively, the supply of hydraulic oil to the input clutch (engaged) and the first clutch (engaged) may be started simultaneously. [Industrial Applicability]

[0061] According to the present disclosure, the shift shock in the transmission 7 is reduced. [Explanation of symbols]

[0062] 7: Transmission, 20: Input shaft, 24: Input low clutch, 25: Input high clutch, 40: First intermediate shaft, 45: First low clutch, 46: First high clutch, 50: Second intermediate shaft, 55: Second low clutch, 56: Second high clutch, 60: Output shaft, 73: Controller, S1-S8: Filling sensors

Claims

1. A method for controlling a transmission including a first transmission shaft, a second transmission shaft arranged downstream of the first transmission shaft in a power transmission path, an input shaft arranged upstream of the first transmission shaft, an output shaft arranged downstream of the second transmission shaft in the power transmission path, an input clutch that transmits rotation of the input shaft to the first transmission shaft in an engaged state, a first clutch that transmits rotation of the first transmission shaft to the second transmission shaft in an engaged state, and a second clutch that transmits rotation of the second transmission shaft to the output shaft in an engaged state, Starting the supply of hydraulic oil to the second clutch; After the filling of the hydraulic oil into the second clutch is completed, the hydraulic pressure of the second clutch is maintained at a predetermined low pressure state; After the filling of the hydraulic oil into the second clutch is completed, starting the supply of the hydraulic oil to the first clutch; After the filling of the hydraulic oil into the second clutch is completed, a supply of hydraulic oil to the input clutch is started; After the first clutch and the input clutch are engaged, the hydraulic pressure of the second clutch is increased from the low pressure state to engage the second clutch; A method for providing the above.

2. The supply of hydraulic oil to the input clutch is started at a timing different from the supply of hydraulic oil to the first clutch. The method of claim 1.

3. A method for controlling a transmission including a plurality of transmission shafts including an input shaft, an output shaft, and an intermediate shaft disposed between the input shaft and the output shaft in a transmission path of a driving force, and a plurality of clutches that connect the plurality of transmission shafts in an engaged state to transmit rotation of the upstream transmission shaft to the downstream transmission shaft, comprising: the plurality of clutches include a most downstream clutch, and a first other clutch and a second other clutch that are disposed upstream of the most downstream clutch, Starting the supply of hydraulic oil to the most downstream clutch among the plurality of clutches to be engaged; After the filling of hydraulic oil into the most downstream clutch is completed, the hydraulic pressure of the most downstream clutch is maintained at a predetermined low pressure state; After the filling of the hydraulic oil to the most downstream clutch is completed, starting the supply of hydraulic oil to the first other clutch; After the filling of the hydraulic oil to the most downstream clutch is completed, starting the supply of hydraulic oil to the second other clutch; increasing the hydraulic pressure of the most downstream clutch from the low pressure state to engage the most downstream clutch after the first other clutch and the second other clutch are engaged; A method for providing the above.

4. The supply of hydraulic oil to the second other clutch is started at a timing different from the supply of hydraulic oil to the first other clutch. The method according to claim 3.

5. A system for controlling a transmission including a first transmission shaft, a second transmission shaft arranged downstream of the first transmission shaft in a power transmission path, an input shaft arranged upstream of the first transmission shaft, an output shaft arranged downstream of the second transmission shaft in the power transmission path, an input clutch that transmits rotation of the input shaft to the first transmission shaft in an engaged state, a first clutch that transmits rotation of the first transmission shaft to the second transmission shaft in an engaged state, and a second clutch that transmits rotation of the second transmission shaft to the output shaft in an engaged state, a sensor for detecting completion of filling of hydraulic oil into the second clutch; a controller that controls the supply of hydraulic oil to the first clutch and the second clutch; Equipped with The controller: A supply of hydraulic oil to the second clutch is started. After the filling of the hydraulic oil into the second clutch is completed, the hydraulic pressure of the second clutch is maintained at a predetermined low pressure state; After the filling of the hydraulic oil into the second clutch is completed, the supply of the hydraulic oil to the first clutch is started; After the filling of the hydraulic oil into the second clutch is completed, the supply of the hydraulic oil to the input clutch is started; After the first clutch and the input clutch are engaged, the hydraulic pressure of the second clutch is increased from the low pressure state to engage the second clutch. system.

Images