JPH07110575B2 - Front wheel speed increasing device for agricultural tractor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a front wheel speed increasing device for an agricultural tractor capable of switching a front wheel between a two-wheel drive state, a four-wheel drive state and a speed increasing state.

(B) Conventional technology Conventionally, in an agricultural tractor that can be switched to a two-wheel drive state, a four-wheel drive state, and a front wheel speed-up state, the operating system that switches between the two-wheel drive state and the four-wheel drive state and the front wheels are switched to a speed-up state. It is already known from Japanese Patent Laid-Open No. 62-85724, etc. that a hydraulic cylinder is provided as a means for increasing the front wheels by providing the hydraulic system separately from the operating system.

(C) Problems to be Solved by the Invention The known agricultural tractor has two problems in order to switch the driving state.
Since it requires two actuation systems, the structure is complicated and the size is increased.

Further, since the oil passage is bored in the transmission shaft, processing and assembling are troublesome.

(D) Means for Solving the Problems The present invention relates to a transmission case 24 that forms a bath oil chamber in the front wheel drive system that is connected to the drive system of the rear wheels to drive input to the differential mechanism 35 of the front wheels. Inside the differential case 21, inside the differential case 21
Side gears 26a, 26 consisting of a pair of bevel gears pivotally supported on the side
Both side gears 26a, 26b between the facing surfaces of b and the side gears 26a, 26b
26b and a hevel gear that meshes with the 26b, and a differential gear for inputting the driving force to the front wheel side and increasing the speed, turning on / off the drive input from the drive system of the rear wheel to the differential gear, and a differential gear. A lock device for switching the rotation of the front wheel to the same speed as the rear wheel or a state in which the speed is increased from the rear wheel is provided, and one side gear shaft of the differential device is used as the output shaft 33 and the other side gear shaft is hydraulically driven. And a shift rail 71 for switching the lock device.The brake shaft 37 is provided with a brake device of the above-mentioned type, and the lock device is provided in the tubular portion 40 on the differential case 21 side of the differential device in which the brake shaft 37 is inserted. The shift rail 71 is provided slidably in the axial direction, and the shift rail 71 is provided with a spool portion 73 constituting a hydraulic system switching valve for opening and closing the brake device, and an oil supply port 76 or a discharge port of the switching valve is formed. Connect to 81 Solves the problems described above by the type 78, 82 and the pipe outside 24 the transmission case.

(E) Action When the shift rail is moved back and forth, the lock device is switched between the two-wheel drive state, the locked four-wheel drive state, and the front wheel speed-up standby state. When an appropriate detection device detects that the front wheels have exceeded a predetermined turning angle without an acceleration stand-by state, a control valve is opened by the detection signal and pressure oil from the pump causes the shift rail to serve as a spool portion. Since the hydraulic oil that is press-fitted into the oil supply port of the switching valve and discharged from the discharge port is press-fitted into the hydraulic cylinder of the brake device via the external pipe, the brake device stops the brake shaft behind the differential device, The front side gear shaft is driven at a double speed, and the front wheels driven thereby are accelerated, so that the aircraft rapidly turns.

(F) Embodiments An embodiment of the present invention will be described with reference to the drawings. Power of the engine 1 is transmitted to a cylinder shaft 6 supported by an intermediate case 5 via a main clutch 2 and gears 3 and 4 in a clutch housing 17. Then, the speed is changed by the PTO transmission 8, the traveling main transmission 9, and the traveling auxiliary transmission 10 in the main mission case 7, and the differential pinion shaft 11 drives the rear axle 13 via the differential mechanism 12 and the final reduction mechanism 14. The drive shaft 16 connected to the front spline of the differential pinion shaft 11 by a joint 15 is the cylindrical shaft 6 described above.
The gear 18 supported by the gear 4 in the clutch housing 17 through the inside of the clutch housing 17 is attached to the front end of the gear 18.
The cylinder portion extending rearward from the differential case 21 that accelerates the front wheels is driven by 9,20.

As shown in FIG. 1, the differential case 21 is housed in a speed change case 24 integrally formed in the lower portion of the clutch housing 17, and the front portion is supported by a bearing 22 in the clutch housing.
17, the rear portion is supported by a holder 25 screwed to the intermediate case 5 via a bearing 23, and the front side gear 26a
The shaft 33 spline-fitted to the front axle 32 is transmitted to the front axle 32, and the front wheel differential mechanism 35 in the front axle 32 drives the front axle 34 via the reduction gear 36. In addition, the brake shaft 37 that is spline-fitted to the rear side gear 26b is the differential case 2
1 is supported by being inserted into a cylindrical portion 40 extending rearward from the hub 1, and a conical hole 44 bored in the outer periphery of the cylindrical portion 40 has a ball 41 fitted into the hole 42 of the cylindrical portion 40. Slide it in and out.
The hub 39 has an inclined surface on both sides of the inner circumference to prevent the balls 41, ... from falling off. The state shown in FIG. 1 is in the foremost position, and the ball 41 escapes from the conical hole 44 to interrupt the transmission. When the ball 41 ... Is pushed into the conical hole 44 ... by sliding to the rear by the shift fork 43, the cylinder 40 and the brake shaft 37 are locked and the rear wheel When the power is transmitted to the front wheels at substantially the same speed, the hub 39 is slid further rearward, and the balls 41, ... Are pushed toward the front of the hub 39, the power is transmitted to the front wheels and the front wheel acceleration standby state is set.

Also, a boss 46 that is spline-fitted to the rear of the brake shaft 37.
The inner circumference of the desks 45 ... constituting the desk brake is spline-fitted on the outer circumference of the mating plate 47, and the projections on the outer circumference of the mating plate 47. , Desk 45 ..., mating plate 47
.. has a gap with respect to the boss 46 and is stopped by the stepped collar 48.

A hole which is fixed to the front end of the intermediate case 5 and is formed near the lower part of the plate 49 which is joined and connected to the clutch housing 17.
51 is a cylinder for operating the desk brake
50 is sealed with an O-ring 52, and a piston 58 with a sealing 59 interposed is inserted into the cylinder 50. A projection 58a on the outer periphery of the piston 58 is loosely fitted into a groove of the holder 25 to prevent rotation of the piston 58. The shaft 63, whose front part is inserted into the center hole and fixed by the snap ring 62, projects into the rear intermediate case 5, and the return spring 60 interposed in this projecting part has a washer 61 and a snap ring 62.
And is covered by the cap 64.

Further, the shift fork 43 is fixed to the shift rail 71 fitted in the holes 70, 70a provided in the clutch housing 17 and the holder 25 so as to be slidable back and forth, with the front end portion of the shift rail 71. It is formed in the spool portion 73 of the switching valve, and both sides of its rear portion are formed as parallel cutout surfaces 74, and an R groove 75 is provided in the front end surface of the boss of the shift fork 43. The hole
The large diameter part and the small diameter part in front of 70 are communicated with the outside by a refueling port 76 and a discharge port 81, and a pipe 78 whose one end is connected to the front refueling port 76 by a bolt 80 and packings 79, 79. The end is connected to the solenoid valve 77a of the control valve 77 of the hydraulic circuit shown in Fig. 11, and the rear discharge port 81
The rear end of the pipe 82, whose front end is connected to the outer end of the cylinder by a bolt 80 and packings 79, 79, is fitted and screwed into the intermediate case 5 as shown in FIGS. A joint 53 tightly inserted in an oil passage 54 communicating with the inside 50 is connected with packings 79, 79 and a bolt 80.

The base of the arm 84, the tip of which is fitted into the recess 83 of the boss of the shift fork 43, is fixed to the control shaft 88 which is supported in the hole 85 of the lower outer wall of the clutch housing 17 through the tubular body 86, A plurality of claws protruding from the inner end surface of the boss 87 fixed to the outer end of the control shaft 88 and a plurality of claws protruding from the outer end surface of the tubular body 86 mesh with each other with a gap in the circumferential direction, The end portion is urged to rotate in one direction by a winding spring 98 engaged with both, the claw is covered with a sealed collar 99, and the tubular body 86 is fitted in a circumferential groove 91 thereof. The plate 92 is positioned by screwing it onto the outer surface of the clutch housing 17 with a bolt 93, and the arm 94 fixed to the outer periphery is interlocked with an operating lever 95 arranged in the front part of the operating section by a telescopically adjustable rod 96. There is.

The steering handle 103 includes a shaft 104, a joint 105, a shaft 106, a gear case 107, an output shaft 120, and a joint 108.
The king pin case is rotated through a, the shaft 108, the joint 109, the steering gear box 110, the pitman arm 110a, and the tie rod 111, and the gear case 10 is rotated.
In FIG. 7, as shown in FIGS. 9 and 10, a bevel gear 113 attached to the shaft 106 and a bevel gear 119 attached to the output shaft 120 mesh with each other, and the output shaft 120 becomes a screw shaft 126 rearward. The slide nut 127 is extended and supported by a bearing 123, the front part is supported by a bearing 122, and the slide nut 127 screwed to the screw shaft 126 has a groove 128 on the outer periphery, and a pair of left and right swings on both side walls of the gear case 107. A pin inserted into the groove 128 by inserting the boss portions of the moving arms 130 and 130 with their axes aligned and positioning them by the retaining rings 132 and 132, and protrudingly provided on the inner surface of the boss portion of the inner swing arm 130 and inserted into the groove 128. 131 is displaced upward by l ₂ from the axis of the screw shaft 126, and the outer swing arm 13
The pin 131 protrudingly provided on the inner surface of the boss portion of 0 is deviated from the axial center of the screw shaft 126 by l ₂ and the swing arm 130,
At the tip of 130, nuts 135,1 spaced l ₁ from the center of rotation
Bolts that are tightened with 35 and have a spherical head 134,134
Is in contact with a pin 136 slidably fitted in a hole in the outer wall of the gear case 107, and the control valve 7
The switch 137 leading to the solenoid valve 77a of 7 is screwed to face each other.

The bolt 141 screwed from the outer side wall of the gear case 107 is screwed into the screw hole 140 formed in the outer swing arm 130 to perform positioning at the time of assembly. Reference numeral 139 is a seal cap press-fitted into the mounting opening.

In the above-mentioned agricultural tractor, when traveling on the road, if the operation lever 95 is set to the 2W position, the hub 39 will move to the first position.
The position shown in the figure is reached, and only the rear wheels are driven.When the operating lever 95 is set to the 4W position during work, the rear part of the hub 39 pushes the balls 41 ... into the conical holes 44. The front wheel is forcibly driven by rotating integrally with the shaft 33, and when the operating lever 95 is set to the rearmost front wheel speed-up standby position, the hub 39 pushes the balls 41 ... It will be in the standby state, the 4WD state will be maintained, and the steering handle to rotate the aircraft in this state
When 103 is rotated to either one, the front wheel is broken, and at that time, the screw shaft 126, which is integrally rotated with the rotation of the output shaft 120 of the gear case 107, moves the slide nut 127 to the front or the rear to swing one side. The arm 130 swings forward, the other swing arm 130 swings backward by the same angle, and the bolt 134 at the lower end of the swing arm 130 swinging forward moves the switch 13
Press 7. This switch 137 has a small push-in length when the cutting angle of the front wheels is small as when correcting the traveling direction,
It does not turn on at that degree, but it turns on when it exceeds a predetermined turning angle, and when the turning angle of the front wheels exceeds the predetermined turning when turning on the aircraft, the control valve 77 The solenoid valve 77a is turned on, and the hydraulic oil pumped by the pump P is pressed into the front hole 70 through the pipe 78.

At that time, since the spool portion 73 of the shift rail 71 is fitted into the small diameter portion of the hole 70 by setting the operation lever 95 described above, the shift rail 71 moves rearward to move the hole 70 and the discharge port.
Simultaneously with the communication with 81, the hub 39 moves rearward to be in the unlocked state, the hydraulic oil is press-fitted into the cylinder 50 through the pipe 82, and the piston 58 slides forward to operate the desk brake, and the brake is applied. Since the shaft 37 is braked and stopped, the front wheels are driven at double speed.

During that time, the shift fork 43 also moves rearward, but since there is a gap in the circumferential direction between the claw of the cylindrical body 86 and the claw of the boss 87, the control shaft 88 is resisted against the winding spring 98.
Only the pivot body rotates, the cylinder body 86 to which the arm 94 is fixed does not rotate, and the operation lever 95 is stopped at the front wheel speed-up standby position.

In FIG. 3, 114 is a normally open type speed-up standby position sensor that is turned on when the operating lever 95 is set to the speed increasing position, and 115 is a normally closed type high speed sensor that is turned off when the auxiliary transmission lever is set to the high speed position. The switch 137 is a normally open type, 116 is a solenoid of the solenoid valve 77a, and 117 is a monitor lamp.

(G) Effect of the Invention Since the present invention is configured as described above, the shift rail 71 can also be used as the spool of the switching valve, and the configuration can be simplified, thereby reducing the operating system of the front wheel speed increasing device. It is lightweight and can reduce costs.

Further, since the oil passage from the switching valve to the hydraulic cylinder of the brake device is constituted by a pipe arranged outside the case, processing and assembly are facilitated, and the cylinder is provided inside the intermediate case outside the bath oil chamber. Therefore, it is possible to prevent the size of the machine body from increasing as much as possible even if the transmission device for increasing the speed of the front wheels is provided.

[Brief description of drawings]

The drawings show one embodiment of the present invention. Fig. 1 is a longitudinal sectional view of a front wheel speed increasing device, Fig. 2 is a transmission system diagram, Fig. 3 is a side view of an agricultural tractor, and Fig. 4 is A vertical plan view of essential parts,
5 is a perspective view of the front part of the shift rail, FIG. 6 is a cross-sectional view of the operation mode conversion device, FIG. 7 is a control circuit diagram, FIG. 8 is a side view of the steering device, and FIG. FIG. 10 is a longitudinal sectional view of the angle detecting device, FIG. 10 is a transverse sectional view of the same as above, and FIG. 11 is a hydraulic circuit diagram. 5 ... Intermediate case, 7 ... Main mission case, 17 ...
Clutch housing, 21 …… differential case, 25 …… holder, 37 …… brake shaft, 39 …… hub, 43 …… shift fork, 50 …… cylinder, 58 …… piston, 71 …… shift rail, 73 …… spool Department, 76 ... Refueling port, 77 ...
Control valve, 77a ... Solenoid valve, 78, 82 ... Pipe, 81 ... Discharge port, 95 ... Operating lever, 107 ... Gear case, 126 ... Screw shaft, 130 ... Oscillating arm, 136 ...
… Pin, 137… Switch,

Claims (1)

[Claims] 1. A differential case (24) in a front wheel drive system for forming a bath oil chamber in a front wheel drive system for driving input to a front wheel diff mechanism (35) in cooperation with a rear wheel drive system. The side gears (26a, 26b) and the side gears (26a, 26), each of which is composed of a pair of bevel gears that are axially supported on the side of the differential case (21) in the inside of 21).
b) A differential gear consisting of a side gear (26a, 26b) meshing with both side-to-side facing surfaces, which inputs and accelerates the driving force to the front wheels, and a rear wheel drive system for the differential gears. And a lock device for switching the rotation of the front wheels through the differential gear to the same speed as the rear wheels or a state in which the speed is increased from the rear wheels. As an output shaft (33), the other side gear shaft as a brake shaft (37) provided with a hydraulically driven brake device, and the differential device differential case (21) in which the lock device is fitted into the brake shaft (37). ) Side cylinder part (40), and a shift rail (71) for switching the lock device is provided slidably in the bath oil chamber, and the brake device is turned on and off in the shift rail (71). Spool that constitutes the switching valve of the hydraulic system to be operated A part (73) of an agricultural tractor, in which pipes (78) and (82) that are connected to the oil supply port (76) or the discharge port (81) of the switching valve are piped outside the speed change case (24). Front wheel speed increasing device.