JP4162302B2 - Differential lock operating device for work vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a differential lock operating device for selectively deactivating a differential device in a work vehicle such as a tractor.
[0002]
BACKGROUND OF THE INVENTION
As such a differential lock operating device, the shift fork engaged with the differential lock clutch is moved in the axial direction of the differential output shaft by the action of hydraulic pressure to obtain the engagement of the differential lock clutch, and the differential device is deactivated. Is known from JP-A-6-257647. In this publication, a shift rod parallel to the differential output shaft is fixed, and the shift fork is slidably supported by a piston formed on the upper end of the shift fork. In addition, a pair of left and right cylinders in which the end portions of the piston portions are oil-tightly fitted are fixedly installed, and hydraulic shift is selectively applied to the left and right cylinders to move the shift fork to the left and right. The engagement of the differential lock clutch is to be obtained.
[0003]
According to this conventional example, since two cylinders are fixedly installed on the shift rod, the number of assembling steps increases and the assembling is troublesome.
[0004]
The present invention is intended to provide a novel hydraulically operated differential lock operating device in a work vehicle, which is much easier to assemble than such a conventional example.
[0005]
SUMMARY OF THE INVENTION
The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.
[0006]
The work vehicle according to claim 1, wherein the shift fork (14) engaged with the differential lock clutch (11) is moved in the axial direction of the differential output shaft (8) by the action of hydraulic pressure to obtain the engagement of the differential lock clutch. In the differential lock operating device, a shift rod (15) parallel to the differential output shaft (8) is slidably supported in a housing (2) in which the differential lock clutch (11) is housed, and the shift fork (14 ) Is fixed to the shift rod (15), while an oil chamber (17) for applying hydraulic pressure is formed to move the shift rod (15) in the engagement direction of the differential lock clutch (11). A hole (26) is formed in an axle case (7) mounted on one side of the housing (2), and the shift rod (15) is connected to the differential output shaft. 8) is shifted to one side in the front-rear direction, and a hole (26) for forming the oil chamber (17) is formed in the axle case (7) in the front-rear direction of the differential output shaft (8). Are provided as a pair of holes (26, 26) symmetrically in the front-rear direction.
[0007]
The differential lock operating device according to claim 1, wherein the pair of axle cases (7, 7) attached to the left and right sides of the housing (2) have the same shape, and the shift rod (15) is connected to the differential lock clutch. other oil chamber for moving the engagement releasing direction (11) to (18), configured to axle case (7) to be mounted on the other side of the housing (2), forming said other oil chamber (18) holes (26) for the advantage of the axle case of the same shape to be attached to the other side of (7), said pair of holes (26, 26) of the housing (2).
[0008]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0009]
In one embodiment of the present invention, the shift rod 15 is arranged to be shifted to one side in the front-rear direction of the differential output shaft 8 to form the oil chambers 17 and 18 in the axle cases 7. A pair of holes 26 is provided symmetrically in the front-rear direction with respect to the position in the front-rear direction of the differential output shaft. According to this structure, the one axle case and the other axle case can be made the same by using one hole 26 for oil chamber formation and leaving the other hole 26 as it is. , Cost is reduced.
Further, according to the present invention, an oil chamber 17 for applying a hydraulic pressure for moving the shift rod 15 in the engagement direction of the differential lock clutch 11 is formed in the axle case 7 mounted on one side of the housing 2 that houses the differential lock clutch. Therefore, the assembly can be completed at the same time that the axle case is mounted on one side of the housing without providing a separate cylinder, and the assembly is extremely easy.
Further, in order to obtain a reliable disengagement of the differential lock clutch 11, another oil chamber 18 for applying a hydraulic pressure for moving the shift rod 15 in the disengagement direction of the differential lock clutch is provided in addition to the housing 2. It is preferable because it is formed in the axle case 7 attached to the side.
[0010]
Other features and advantages of the present invention can be clearly understood from the following description with reference to the accompanying drawings.
[0011]
【Example】
In FIGS. 1 and 2, reference numeral 1 denotes a tractor mission case, and 2 denotes a rear housing subsequent thereto. A propeller shaft 3 extending from the inside of the transmission case 1 into the rear housing 2 is provided, and a large bevel gear 5 meshed with a bevel pinion 4 integrally formed at the rear end of the propeller shaft 3 is used as an input gear. A differential 6 for left and right rear wheels (not shown) is provided in the rear housing 2.
[0012]
As shown in FIG. 2, left and right rear wheel axle cases 7 are mounted on the left and right side surfaces of the rear housing 2, and the left and right output shafts (differential output shafts) 8 of the differential device 6 extend into the axle case 7. It is extended. The left and right rear wheel axles 9 are disposed concentrically with the output shaft 8 and are supported by the axle case 7. On the output shaft 8 on one side, a differential case 10 of the differential device 6 is selectively coupled to the output shaft 8 by meshing of the claws 10a and 11a, so that the differential device 6 is deactivated. The clutch 11 is slidably provided. Disc brakes 12 having the axle case 7 as a brake case are provided at the inner ends of the left and right axle cases 7. Adjacent to the left and right disc brakes 12, left and right planetary gear speed reducers 13 are provided in the axle case 7.
[0013]
In order to operate the differential lock clutch 11, a shift fork 14 engaged with the clutch 11 is supported on both side walls of the rear housing 2 in parallel with the output shaft 8 as shown in FIGS. It is supported by the rod 15. The shift fork 14 is fixed to the shift rod 15 by a bolt 16, and the shift rod 15 is formed so as to be non-rotatable and slidable by forming a pair of flat portions 15 a at portions that are fitted to both side walls of the rear housing 2. Has been.
[0014]
Similarly, as shown in FIGS. 2 and 3, oil chambers 17 and 18 facing the shift rod 15 are formed in the left and right axle cases 7, and pistons 19 and 20 are provided in these oil chambers 17 and 18, respectively. It is oil-tightly fitted. Each piston 19, 20 has rod portions 19 a, 20 a facing the shift rod 15. Pipes 23 and 24 are connected to the oil chambers 17 and 18 through pipe joints 21 and 22, respectively. A spring 25 having a base end is applied to the shift fork 14 on the inner surface of the side wall on the one side of the rear housing, and the shift fork 14 is urged to move together with the shift rod 15 in the disengagement direction of the differential lock clutch 11. It is.
[0015]
Therefore, when the hydraulic circuit is switched from the state in which the hydraulic pressure is applied to the oil chamber 18 and the hydraulic pressure is applied to the oil chamber 17, the shift rod 15 and the shift fork 14 are slid and the differential lock clutch 11 is engaged. . When the differential lock clutch 11 is engaged, the spring 25 acts to engage the clutch 11 in a shock-absorbing manner.
[0016]
As shown in FIG. 1, the shift rod 15 is arranged to be shifted to one side (front side in the illustrated example) of the output shaft 8 in the front-rear direction, and the hole 26 of the axle case 7 for forming the oil chambers 17 and 18 is illustrated in FIG. As shown in FIG. 4, a pair is provided symmetrically in the front-rear direction with respect to the position of the output shaft 8 in the front-back direction. Therefore, the same left and right axle cases 7 can be used. The reason why the shift rod 15 is shifted to one side in the front-rear direction of the output shaft 8 will be described later.
[0017]
The other parts will be described. As shown in FIG. 2, the differential device 6 shown in the figure is provided with two differential pinion shafts 28 arranged in a cross shape, and two pairs on the two differential pinion shafts 28 are provided. The drive bevel gear 29 is meshed with a pair of driven bevel gears 30 on the left and right output shafts 8 to constitute the differential 6.
[0018]
Similarly, as shown in FIG. 2, each of the disk brakes 12 includes three outer disks 31 that are supported by the axle case 7 so as to be slidable, and two sheets that are supported by the output shaft 8 so as to be slidable only. The inner disks 32 are alternately arranged between the pistons 33 in the axle case 7 and the pressure receiving surfaces 34 of the rear housing 2.
[0019]
Each of the reduction gears 13 includes a sun gear 35 formed integrally with the output shaft 8, an internal gear 37 fixed to the axle case 7 by a bolt 36 passed from outside the case 7, and a shaft 39 to a carrier 38 fixed to the axle 9. The three planetary gears 40 meshed with the supported sun gear 35 and the internal gear 37 are configured as planetary gear type. The piston 33 of the disc brake 12 is supported by an internal gear 37 and is prevented from rotating by a pin 41 inserted into the hole of the piston 33.
[0020]
As shown in FIG. 1, a PTO shaft 43 extending rearward from the rear housing 2 is provided, and a hydraulic lift device 44 having left and right lift arms 44a is provided on the upper surface of the rear housing 2. The PTO shaft 43 includes a hydraulically operated PTO clutch 47 provided between the transmission shaft 45 transmitted from the transmission case 1 and another transmission shaft 46 disposed on the extension line, and the transmission shaft 46 and the PTO shaft 43. It is driven via a PTO transmission 49 that is provided in between and obtains a three-stage shift by a shift clutch 48. A support plate 50 fixedly supported on a hydraulic lift case 44b of the hydraulic lift device 44 is provided, and an intermediate gear 51 supported on the support plate 50 so as to be freely rotatable is fixedly installed on the transmission shaft 45. And a gear 54 supported by the hydraulic lift case 44b together with the rotary shaft 53. The rotary shaft 53 is used to drive two hydraulic pumps 55 and 56 mounted on the front surface of the hydraulic lift case 44b. A forward projecting portion 44c is formed in the hydraulic lift case 44b, and a valve mechanism 57 is installed on the projecting portion 44c.
[0021]
FIG. 5 shows a hydraulic circuit for operating the differential lock clutch 11 together with other hydraulic circuits. Oil passages 61 and 62 connected to the oil chambers 17 and 18 are connected to a discharge oil passage 59 of the hydraulic pump 55 via a direction switching valve 60. The direction switching valve 60 connects the discharge oil passage 59 to the oil chamber 18 via the oil passage 62, the position I where the differential lock clutch 11 is maintained in the disengaged state, and the discharge oil passage 59 via the oil passage 61. And a position II where the differential lock clutch 11 is engaged by connecting to the oil chamber 17.
[0022]
Similarly, as shown in FIG. 5, the PTO clutch 47 is provided with a brake 64 for braking the clutch driven side in the disengaged state of the clutch 47, and the PTO transmission 49 is engaged with the engagement of the PTO clutch 47. An interlock mechanism 65 is provided to prevent the shift clutch 48 from being displaced in the state. The discharge oil passage 59 of the hydraulic pump 55 is also connected to the PTO clutch 47, the brake 64, and the interlock mechanism 65 via the direction switching valve 66. That is, an oil passage 67 connected to the PTO clutch 47 and an oil passage 68 connected to the brake 64 and the interlock mechanism 65 are connected to the secondary side of the direction switching valve 66, and the latter oil passage 68 performs a relief operation at a relatively low pressure. It is connected to the former oil passage 67 through a relief valve 69. The oil passage 67 is connected in parallel with a modulated relief valve mechanism 70 that gradually increases the hydraulic pressure applied to the PTO clutch 47. The direction switching valve 66 has a neutral position N at which the hydraulic pressure is released from the hydraulic release chamber 64a of the hydraulic clutch 47 and the brake 64 and the hydraulic chamber 65a of the interlock mechanism 65, and a discharge oil passage 59 via the relief valve 69. 47 and an operating position I for connecting the discharge oil passage 59 to the oil chambers 64a and 65a. At the neutral position N of the direction switching valve 66, the brake 64 is braked by the spring 64b by removing the hydraulic pressure from the operation releasing oil chamber 64a, and at the operating position I of the direction switching valve 66, the interlock mechanism 65 is operated by the operating oil chamber 65a. Due to the action of hydraulic pressure on the motor, the interlock operation is performed against the spring 65b for releasing the operation.
[0023]
A main relief valve 71 is used to set the oil pressure of the discharge oil passage 59, and a secondary relief valve 72 for setting the lubricating oil pressure is provided at the subsequent stage. A lubricating oil passage 73 for the PTO clutch 47 is led out from the oil passage between the relief valves 71 and 72, and the relief oil from the modulated relief valve mechanism 70 is joined to the lubricating oil passage 73.
[0024]
A discharge oil passage 74 of the hydraulic pump 56 is connected via a direction switching valve 75 to a hydraulic device 76 such as a hydraulic cylinder (not shown) that controls the horizontal posture of the ground working machine connected to the rear portion of the tractor. Before and after the direction switching valve 75, a hydraulic outlet port 77 and a hydraulic pressure return port 78 connected to an operating hydraulic device (not shown) such as a front loader are provided.
[0025]
A line filter 81 and a relief valve 82 are inserted in parallel in an oil passage 80 between the oil tank 79 and the hydraulic pumps 55 and 56. When the line filter 81 is clogged, the relief valve 82 performs a relief operation to ensure the amount of oil for the hydraulic pumps 55 and 56.
[0026]
In the above embodiment, in addition to the piston 19 for moving the shift rod 15 in the engagement direction of the differential lock clutch 11, the piston 20 for moving the shift rod 15 in the engagement release direction of the differential lock clutch 11 is provided. The latter piston 20 is omitted, and the structure in which the differential lock clutch 11 is moved in the disengagement direction exclusively by a spring corresponding to the spring 25 can be used. It is also possible to omit the piston 19 or the pistons 19 and 20 and provide an oil chamber that directly applies hydraulic pressure to the end surface of the shift rod 15. FIG. 6 shows a second embodiment which is considered to be the simplest.
[0027]
In the embodiment of FIG. 6, the pistons 19 and 20 are eliminated and the oil chamber 17 is formed only in the axle case 7 on one side. Disengagement of the differential lock clutch 11 is obtained by sliding the shift rod 15 with a spring 25 provided in the same manner as described above. Engagement of the differential lock clutch 11 applies hydraulic pressure to the oil chamber 17 and is applied to the end surface of the shift rod 15. On the other hand, it is obtained by sliding the shift rod 15 by applying the hydraulic pressure.
[0028]
The reason why the shift rod 15 is shifted in front of the output shaft 8 as shown in FIG. 1 is to share the rear housing 2 with the tractor provided with the mechanical differential lock operating mechanism. That is, in the case where a mechanical differential lock operating mechanism is provided, the clutch pedal 90 shown in phantom lines in FIG. 1 is attached to the shift rod 15 outside the rear housing 2. In general, as shown in FIG. 7, the shift rod 15 is rotatably supported, and the shift fork 14 is slidably supported on the shift rod 15 via a cam hardware 91 having a cam surface 91a inclined in the circumferential direction. Then, a pin 93 slidably contacting the cam surface 91 a under the bias of the cam hardware 91 by the spring 92 is implanted in the shift rod 15. Therefore, when the shift rod 15 is rotationally displaced, the shift fork 14 is slid. If such a mechanical differential lock operating mechanism is provided and the shift rod 15 is provided immediately above the output shaft 8, the position of the clutch pedal 90 will be rearward, and when the pedal 90 is depressed, it will be the rear housing 2. It interferes with the axle case 7 on the side. For this reason, as shown in the figure, the shift rod 15 is arranged at the foremost position of the rear housing 2, so that a tractor provided with a mechanical differential lock operating mechanism and a tractor provided with a hydraulic differential lock operating mechanism are used. The rear housing 2 can be shared.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view showing a part of a tractor equipped with an embodiment of the present invention.
FIG. 2 is a cross-sectional front view of the tractor.
FIG. 3 is a cross-sectional front view showing a part of FIG. 2 in an enlarged manner.
4 is a cross-sectional view taken substantially along the line IV-IV in FIG. 2;
FIG. 5 is a circuit diagram showing a hydraulic circuit.
FIG. 6 is a cross-sectional front view similar to FIG. 3, showing a second embodiment of the present invention.
FIG. 7 is a schematic view showing a part of a conventional mechanical differential lock operating device.
[Explanation of symbols]
2 Rear housing 6 Differential device 7 Rear axle case 11 Differential lock clutch 14 Shift fork 15 Shift rod 16 Bolts 17 and 18 Oil chambers 19 and 20 Pistons 23 and 24 Pipe 26 Hole 60 Directional switching valve

Claims (2)

  In a diff lock operating device in a work vehicle that obtains engagement of a differential lock clutch by moving a shift fork (14) engaged with the differential lock clutch (11) in the axial direction of the differential output shaft (8) by the action of hydraulic pressure, A shift rod (15) parallel to the differential output shaft (8) is slidably supported in a housing (2) that houses the differential lock clutch (11), and the shift fork (14) is attached to the shift rod. A hole (26) for forming an oil chamber (17) for applying hydraulic pressure to move the shift rod (15) in the engagement direction of the differential lock clutch (11), while fixing to (15). It is formed in an axle case (7) attached to one side of the housing (2), and the shift rod (15) is arranged in the front-rear direction of the differential output shaft (8). The hole (26) for forming the oil chamber (17) in the axle case (7) is symmetrical to the front and rear with respect to the position in the front-rear direction of the differential output shaft (8). The differential lock operating device is provided as a pair of holes (26, 26). In differential-lock operation apparatus according to claim 1, engagement of the housing (2) of a pair of axle case that attached to the left and right sides of (7.7) and the same shape, said shift rod (15) a differential lock clutch (11) The other oil chamber (18) to be moved in the releasing direction is formed in the axle case (7) mounted on the other side of the housing (2), and a hole (26 for forming the other oil chamber (18) is formed. ), the other axle case having the same shape (7) to be mounted on the side, differential lock operating device, characterized by utilizing the pair of holes (26, 26) of the housing (2).

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