JPH09184559A - Transmission of working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a transmission compactly in which front/rear wheels and PTO shaft can be driven by a hydraulic continuously variable transmission and restrain a backward shift at a high speed position when a gear type transmission is installed. SOLUTION: In this transmission, a hydraulic continuously variable transmission is stored in a first chamber R1 formed in a housing and a gear type transmission is stored in a second chamber R2. In this case, a hydraulic pump P1 and hydraulic motor M for constituting the hydraulic continuously variable transmission are divided up and installed and fluid-connected mutually on the inner/outer surfaces of a front wall 10a for constituting the first chamber of the housing respectively and one side of the hydraulic pump and hydraulic motor is stored in the first chamber and the other is positioned in the outside of the first chamber, while a front wheel drive shaft 13.44 interlocked and connected to the gear type transmission is supported rotatably in the first chamber and projected forward through a front wall.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arrangement structure of front wheel drive shafts arranged in a housing of a transmission for driving front wheels and rear wheels of a traveling vehicle, and a check mechanism for reverse shift.

[0002]

2. Description of the Related Art Transmissions for driving front and rear wheels equipped with a hydraulic continuously variable transmission have been known. For example, JP-A-7-117500
No. technology. This technology drives a hydraulic pump of a hydraulic continuously variable transmission by an input shaft to which engine power is input,
From the rear end of the output shaft of the hydraulic motor of the hydraulic continuously variable transmission, the power is transmitted to the differential gear device via the gear transmission to drive the rear wheels, and the front end of the output shaft projects forward to connect the universal joint. It was configured to drive the front wheels through. Further, in the hydraulic continuously variable transmission equipped with the gear type transmission, when the gear type transmission is shifted to the high speed operation position, the speed change operation pedal of the hydraulic type continuously variable transmission is operated to the reverse side by a certain speed or more. Techniques that are configured so that they cannot be performed are also known. For example, it is a technique of Japanese Utility Model Publication No. 62-5942.

[0003]

In the former prior art,
Both the hydraulic pump and the hydraulic motor are housed in the housing, and since the front wheels are driven directly from the output shaft of the hydraulic motor of the hydraulic continuously variable transmission, when the gear type transmission is switched, In order to avoid the situation where the speed ratio between the front wheels and the rear wheels becomes unsynchronized and the gear type transmission is switched to the high speed side, it is necessary to provide a check mechanism that does not drive the front wheels. . Also,
As in the latter prior art, the restraint device for the reverse side with respect to the shift operation tool of the hydraulic continuously variable transmission is such that the operation lever and the hydraulic continuously variable transmission arranged outside the housing for shifting the gear type transmission are used. A check link is formed outside the housing between the device and the gear shift operation pedal to form a check mechanism, so if dust or the like gets caught in the link for a long period of time, it cannot be completely checked. Sometimes occurred and was unreliable.

[0004]

The present invention is configured as follows to solve the above problems. That is, a transmission for transmitting engine power to the front and rear wheels,
A hydraulic continuously variable transmission capable of switching between forward and backward movements and a gear type transmission capable of changing the traveling speed to a plurality of stages are interlockingly connected, and the hydraulic pressure is provided in a first chamber formed in a housing of the transmission. In which the gear type transmission is housed in the second chamber, the hydraulic type transmission is provided on each of the inner and outer surfaces of the front wall of the housing which constitutes the first chamber. A hydraulic pump and a hydraulic motor that form a gear transmission are distributed and mounted and fluidly connected to each other, one of the hydraulic pump and the hydraulic motor is housed in the first chamber, and the other is located outside the first part. On the other hand, the front wheel drive shaft, which is interlockingly connected to the gear type transmission, is rotatably supported in the first chamber and protrudes forward through the front wall.

Further, a clutch mechanism for engaging and disengaging the front wheel drive shaft with respect to the output portion of the gear type transmission is housed in the first chamber.

Further, the front wheel drive shaft is composed of a first shaft portion and a second shaft portion which are rotatably fitted to each other on the same axis.
Each shaft portion was supported by a front wall and a rear wall that compose the first chamber, and a clutch mechanism was provided between the first shaft portion and the second shaft portion to engage and disengage them. .

The speed control arm of the hydraulic continuously variable transmission is arranged on one side of the housing, and the operation arm of the clutch mechanism is arranged on the other side of the housing.

Further, the transmission for transmitting the engine power to the traveling wheels is linked with a hydraulic continuously variable transmission capable of switching between forward and backward movements and a gear type transmission capable of changing the traveling speed to a plurality of stages. In the above configuration, the hydraulic continuously variable transmission is accommodated in a first chamber formed in the housing of the transmission, and the gear type transmission is accommodated in a second chamber. On each of the inner and outer surfaces of the front wall of the room, the hydraulic pump and the hydraulic motor that constitute the hydraulic continuously variable transmission are distributed and mounted and fluidly connected to each other, and one of the hydraulic pump and the hydraulic motor is connected to the first A speed control lever of the hydraulic continuously variable transmission when the gear type transmission is switched to a high speed side while the other is located outside the first part while being housed in one room Restraining mechanism to prevent more than a predetermined speed increasing operation to the reverse side by accommodating the first chamber.

Further, the check mechanism is interlocked with the switching operation of the gear type transmission, and the cam means is displaceable in the machine front-rear direction in the first chamber, and the backward movement of the speed control lever on the outer wall surface of the housing. A check pin that is provided at a predetermined restriction position in the side gear shift range and has one end side that can freely move back and forth toward the speed control lever, and that is swingably supported around the machine longitudinal axis in the first room, A check arm including a first arm portion that contacts the cam means and a second arm portion that contacts the other end of the check pin,
When the first arm part rides on the shallow part of the cam means by the switching operation of the gear type transmission to the high speed side, the check arm swings so that the second arm part pushes the check pin toward the speed control lever. As configured.

Further, the transmission system from the engine to the traveling wheels is provided with a hydraulic continuously variable transmission capable of switching between forward and backward movements and a gear type transmission capable of changing the traveling speed to a plurality of stages. A check mechanism is provided in the housing for restricting the speed increasing operation toward the reverse side by the operation tool of the continuously variable transmission when the change operation tool is located on the high speed side.

Further, a portion of the front wall of the housing to which the hydraulic pump and the hydraulic motor are mounted is separable from the housing.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the structure of an embodiment of the present invention shown in the accompanying drawings will be described. FIG. 1 is an overall side view of the work vehicle.

Referring to FIG. 1, a description will be given of the overall construction of a mid-mount mower type work vehicle equipped with the transmission of the present invention. The engine E is housed in the hood 1 on the front of the fuselage, and the dashboard 2 is installed at the rear of the hood 1.
And a handle 3 is arranged on the dashboard 2. Step 4 on both sides of the bottom of the dashboard 2
And place the brake pedal in step 4 on the left side.
R is arranged, and a main transmission pedal (not shown) is arranged in the step on the right side. Seat 6 behind the dashboard
And a sub-transmission lever 7 and a PTO switching lever 9 are arranged on the side of the seat 6.

A transmission of the present invention is arranged below the seat 6, and the transmission includes a hydraulic continuously variable transmission, a gear type transmission, and a PTO transmission in a housing consisting of a front case 10 and a rear case 11. It is configured to store. The input shaft 12, the first shaft portion 13 of the front wheel drive shaft, and the mid PTO shaft 1 are located forward from the front case 10.
4, the crankshaft of the engine E is interlockingly connected to the input shaft 12 via a damper in the machine body frame 15 and a transmission shaft 16. The first shaft portion 1 of the front wheel drive shaft
3, an input shaft 19 projecting from a front axle case 18 is connected via a universal joint 17,
Power is transmitted to the input shaft 19 so that the front wheels 20 pivotally supported on the left and right sides of the front axle case 18 can be driven. 22 is a front wheel 2 when the handle 3 is operated.
It is a hydraulic cylinder for steering 0. The input shaft 2 protruding from the gear box 25 of the mower 24 via the universal joint 23 to the mid PTO shaft 14.
It is interlockingly connected with 6. The mower 24 is configured to be able to move up and down with respect to the ground in a space between the front wheels 20 and the rear wheels 21 by an elevator device (not shown).

Axles 27 project laterally from both side surfaces of the rear part of the rear case 11 so that the rear wheels 21 can be supported by the axle. On the upper surface of the rear case 11, a hydraulic cylinder case 29 for a hydraulic lifting device is placed.
A pair of left and right lift arms 30 is projected rearward from 9. A plate provided with a drawbar hitch 32 at the lower end is mounted on the rear surface of the rear case 11 to pivotally support the front part of the lower link 31. Then, the lift arm 30
The lower link 31 and a top link (not shown) allow the working machine to be mounted vertically, and the drawbar hitch 32 allows a towing working machine to be mounted.

Next, the structure of the transmission will be described. 2 is a skeleton diagram of power transmission of the traveling system and the PTO system, FIG. 3 is a side sectional view of the front case portion, and FIG. 4 shows a gear transmission in the second chamber and a power transmission mechanism to the mid PTO shaft. FIG. 5 is a side sectional view, FIG. 5 is a side sectional view of the upper part of the housing showing the power transmission mechanism to the front wheel drive shaft and the rear PTO shaft, and FIG.
FIG. 7 is an enlarged sectional view of the O-clutch, FIG. 7 is a front view showing the arrangement of the power transmission shafts of the traveling system and the PTO system, and FIG.
-X arrow cross-sectional view, FIG. 9 is a plan cross-sectional view of the gear shift operation unit of the gear type transmission and the reverse shift control device unit linked to the gear shift operation unit, and FIG. 10 is the right YY arrow view in FIG. A sectional view and a sectional view taken along the arrow Y'-Y 'on the left side, FIG. 11 is a front perspective view of the housing, and FIG. 12 is a hydraulic circuit diagram.

The housing is joined to a front case 10 and a rear case 11 so as to be separable in the front and rear. The front case 10 has a front wall 10a on the front surface and a rear wall 10b on the rear surface, and the front wall 10a. A flange portion 10h is formed around the
A center section 40 is fixed to close an opening provided in a part of the front wall 10a of the front case 10, and a first chamber R1 is provided between the rear wall 10b of the front case 10 and the center section 40. Is forming. The center section 40
Is for mounting and supporting a hydraulic pump P1 and a motor M, which will be described later, and constitutes a part of the front wall 10a.
Then, the front wheel drive shafts 13 and 4 are provided at a portion of the front wall 10a which is located downward in the vertical direction and substantially in the center in the horizontal direction.
A through hole for inserting 4 is formed. And
A partition wall 11a is provided at a substantially central portion of the rear case 11 in the front-rear direction of the body to partition the inside of the rear case 11 into front and rear parts.
A second chamber R between the rear wall 10b of 0 and the partition wall 11a.
2, the partition wall 11a and the rear wall 11c of the rear case 11 are formed.
A third room R3 is formed between and. Furthermore, a recess is formed on the outer surface of the rear wall 10c of the rear case 11, and the recess is closed by the lid 79 to form a fourth chamber R4.

In the first chamber R1 between the center section 40 and the rear wall 10b, the input shaft 12 is supported on the upper part, while the hydraulic pump P1 is mounted on the inner surface of the center section 40, The input shaft 12 drives the hydraulic pump P1. A pump case 105 accommodating a charge pump P2 is mounted on the outer surface of the center section 40, and the charge pump P2 is attached by the input shaft 12.
Is driving. In addition, the traveling first transmission shaft 41 is supported at approximately the center in the vertical direction in the first room R1. A hydraulic motor M is mounted on the outer surface of the center section 40 so that its rotation axis is located on the same axis as the traveling power transmission shaft 41. A hydraulic continuously variable transmission is configured by fluidly connecting the hydraulic pump P1 and the hydraulic motor M through an oil passage, which will be described later, bored in the center section 40.

The hydraulic pump P1 is constructed as follows. That is, the cylinder block 51 is rotatably arranged on the pump attachment surface 50 provided on the inner surface of the upper portion of the center section 40, and the input shaft 12 is provided at the center of the cylinder block 51.
Are penetrated through and engaged. A piston 52 is inserted into the plurality of cylinder holes of the cylinder block 51 via an urging spring.
································· ···
The thrust bearing 53a of the movable swash plate 53 is in contact with the head of 52 ... The movable swash plate 53 can be tilted about the trunnion shafts 53b and 53b protruding laterally, and as shown in FIG. 8, one of the trunnion shafts 53b and 53b is rotatable on the inner wall side surface of the front case 10. The other side is rotatably supported by a side plate 60 that closes an opening formed on the right side surface of the front case 10. Further, a neutral return spring 59 is externally fitted on the other trunnion shaft 53b to urge the movable swash plate 53 to return to the neutral position, and the trunnion shaft 53b further extends and projects from the side plate 60, The speed control arm 61 is fixed to this protruding portion. The speed control arm 61 is interlocked with a main transmission pedal (not shown) arranged on the step 4 via a connecting rod 125 described later.

A motor attachment surface 54 is formed on the lower outer surface of the center section 40, and a cylinder block 55 is rotatably arranged on the motor attachment surface 54.
The output shaft 45 penetrates and is engaged with the center of the cylinder block 55. A plurality of pistons 56, 56 are provided in the plurality of cylinder holes of the cylinder block 55 via bias springs.
... are fitted so that they can reciprocate. The piston 56
The head of the is contacted with the fixed swash plate 57. The fixed swash plate 57 and the cylinder block 55 are housed in a motor case 58 mounted on the front surface of the center section 40. Therefore, since nothing is arranged on the lower inner surface of the center section 40 on the side opposite to the motor-attached surface 54, a high-speed reverse check mechanism and a front-wheel drive clutch mechanism C, which will be described later, are provided in the first room R1. There is a large space for accommodation.

The hydraulic pump P1 and the hydraulic motor M are provided with a pair of oil passages 4 formed in the center section 40.
0a.40b (FIG. 9) to form a closed circuit by the oil passages 40a.40b, and pressure oil is supplied from the charge pump P2 provided on the input shaft 12 into the closed circuit. . As shown in FIG. 10, the oil filter 46 is disposed on the outer surface of the lower portion of the front case 10.
As shown in FIG. 1, a filter mounting portion 10g is formed on the lower outer surface of the front case 10. The oil filter 46
As shown in FIG. 8, the inlet hole 46a of No. 2 communicates with the second chamber R2 through a hole 120 formed in the rear wall 10b. The lubricating oil stored in the second room R2 is
From the inlet hole 46a into the oil filter 46, and after being filtered by the oil filter 46, the oil passage 121a provided on the side wall of the front case 10 from the outlet hole 46b (FIG. 10) of the oil filter 46 and the side plate 60. Oil passage 121 formed on the mating surface between the inner surface and the outer surface of the front case 10.
It is guided to the suction port of the charge pump P2 through b, the oil passage 121c opening in the front wall 10a of the front case 10, and the oil passage in the center section 40.

Since the hydraulic pump P1 is housed in the first chamber R1 as described above, the oil accumulated therein has a relatively high temperature due to long-term operation. On the other hand, since the gear type transmission and the PTO transmission, which will be described later, are only housed in the second chamber R2, the oil therein does not become too hot. Therefore, the oil having a relatively low temperature is sucked into the charge pump P2 through the oil filter 46 and supplied to the closed circuit of the hydraulic continuously variable transmission, thereby improving the durability. Further, by centrally arranging the related elements of the oil filter 46 in the front case 10,
Rear case 11 with a short and simple oil passage configuration without piping
The oil inside can be inhaled to reduce the cost.

The pressure of the oil discharged from the discharge port of the charge pump P2 is set by the main relief valve 47 as shown in FIG. 12, and a part of the pressure oil is stored in the case 105 of the charge pump P2. Resistance valve 48
Switch valve 2 for power steering through piping via
Oil is sent to the switch valve 2 by the rotation of the handle 3.
When 00 is switched, oil is sent to the steering cylinder 22 and the front wheels 20 are steered. The return oil from the steering cylinder 22 is returned to the inside of the oil cooler 123 and the motor case 58 through the pipe, and further through the through hole of the center section 40 and the first chamber R1 and the bearing portion of the rear wall 10b. It flows to the second room R3. Further, the discharge oil from the charge pump P2 is regulated by the pressure reducing valve 49 installed in the case 105 of the charge pump P2, and is replenished into the closed circuit by the check valve 124 on the low pressure side of the check valves 124. Further, when the oil passage 40a or 40b on the high pressure side becomes higher than the set pressure, it is relieved by the relief valve 104. When the pressure reducing valve 49 is pressure-regulated, the drain oil discharged from here is P
Oil is sent to the TO clutch / brake control valve 101.

Further, the oil passage 40a, which constitutes the closed circuit,
As shown in FIG. 9, the check valve 102, 102 and the oil filter 103.1 are provided between the first chamber R1 and the first chamber R1.
03 is interposed, and when the engine E is stopped and the vehicle is parked on a slope, etc., the hydraulic motor M and the hydraulic pump P1.
When the oil in the closed circuit leaks from each part such as a shortage of hydraulic oil, the lubricating oil in the first chamber R1 can be supplied to the closed circuit from the check valve 102 through the oil filters 103. There is. As shown in FIG. 3, the main relief valve 47 is provided above the center section 40 to set the discharge hydraulic pressure of the charge pump P2 to a specified pressure.

Further, as shown in FIGS. 2, 4, and 5, the partition wall 11 of the rear wall 10b of the front case 10 and the rear case 11 is formed.
PTO counter shaft 39, PTO transmission shaft 3 between a and
3. The traveling power transmission second shaft 42 and the traveling power transmission third shaft 43 are rotatably suspended in parallel in the front-rear direction via bearings. Further, a counter shaft 99 and a mid-PTO shaft 14 are rotatably traversed in the front-rear direction through bearings in bulging portions 10i and 11b formed to protrude diagonally downward at the joint between the front case 10 and the rear case 11. It is suspended.

Further, as shown in FIG. 5, the rear case 1 is
In the third chamber R3 between the partition wall 11a of No. 1 and the rear wall 11c of the rear case 11, a rear PTO drive shaft 35 is provided horizontally at the top, and a differential gear device D and a hydraulic lift are provided at the bottom. The oil filter 38 of FIG. The rear PT
The rear end of the O drive shaft 35 is inserted into the fourth chamber R4,
The gear 3 is mounted on the rear PTO drive shaft 35 in the fourth room R4.
5a is provided, and the fourth wall between the rear wall 11c and the lid 79 is provided.
The rear PTO shaft 36 in the room R4 of the fourth room R4 so that the rear PTO shaft 36 is rotatably mounted horizontally, and the gear 37
Is fixed, and the gear 37 is meshed with the gear 35a. The rear end of the rear PTO shaft 36 is projected rearward from the lid 79.

Next, the power transmission mechanism of the transmission will be described with reference to FIGS. Power is transmitted to the input shaft 12 from the engine E via the damper and the transmission shaft 16 as described above. The input shaft 12 drives the hydraulic pump P1 and the charge pump P2, and the hydraulic oil from the hydraulic pump P1 is supplied to the hydraulic motor M to drive the output shaft 45. The traveling first transmission shaft 41 is provided at the rear end of the output shaft 45.
The front end of the first transmission shaft 41 is spline-fitted so as to rotate integrally, and the gear 62 is fixedly provided at the rear end that penetrates the rear wall 10b of the first traveling transmission shaft 41.

Next, the gear type transmission will be described. As shown in FIGS. 2 and 4, the gear 62 on the traveling first transmission shaft 41 is a large-diameter gear 6 fixed on the traveling second transmission shaft 42.
3, the large diameter gear 63 is always meshed with the small diameter gear 65a rotatably loosely fitted on the traveling third transmission shaft 43. Further, a small diameter gear 64 is provided on the second traveling transmission shaft 42, and the small diameter gear 64 is always meshed with a large diameter gear 66a rotatably loosely fitted on the third traveling transmission shaft 43.
A spline collar 67 is fixed on the shaft 43 between the small-diameter gear 65a and the large-diameter gear 66a, and a slider 68 is fitted on the spline collar 67 so as not to be relatively rotatable and slidable in the axial direction.

As shown in FIG. 10, the shifter 106 is formed in the annular recess 68a formed on the outer periphery of the slider 68.
Is locked. The shifter 106 is a shifter shaft 10.
7, the front portion of the shifter shaft 107 is linked to a reverse speed change check mechanism of a speed control arm 61 described later, and the rear portion is engaged with a pin protruding from the arm 108. The arm 108 is fixed to the inner end of a height switching shaft 109 pivotally supported on the left side surface of the rear case 11, and the height switching arm 110 is fixed to the outer end of the height switching shaft 109.
Reference numeral 10 is connected to the above-described auxiliary transmission lever 7 via a link or the like.

The engaging elements 65b and 66b provided on the gears 65a and 66a are configured to be able to mesh with the internal teeth of the slider 68, and when the sub-transmission lever 7 is operated,
Height switching arm 110, height switching shaft 109, arm 10
8, the slider 68 is slid in the axial direction through the shifter shaft 107 and the shifter 106, and the gears 65a and 65a
One of the points b is locked to the traveling third transmission shaft 43 to enable high and low two-speed shifting.

Therefore, when the auxiliary shift lever 7 is operated to the high speed position, the inner teeth of the slider 68 are moved to the small diameter gear 65.
The power from the output shaft 45 is meshed with the engaging element 65b of a and the traveling first transmission shaft 41 → gear 62 → large diameter gear 63 → small diameter gear 65a → engaging element 65b → slider 68 → spline collar 67 → running first The high-speed rotation power is transmitted from the bevel pinion 69 provided at the rear end of the traveling third transmission shaft 43 to the axle 27 via the differential gear device D by being transmitted to the third transmission shaft 43.

When the auxiliary transmission lever 7 is operated to the low speed position, the internal teeth of the slider 68 mesh with the engagement element 66b of the large diameter gear 66a, and the power from the output shaft 45 causes the power from the output shaft 45 to travel. → gear 62 → large diameter gear 63 → second traveling transmission shaft 42 → small diameter gear 64 → large diameter gear 66a → engager 6
6b-> slider 68-> spline collar 67-> traveling third transmission shaft 43 is transmitted, and in the same manner as described above, low-speed rotation power is transmitted to the axle 27.

Next, a check mechanism for the reverse speed change of the speed control arm 61 will be described. As shown in FIGS. 3, 8 and 9, the front end of the shifter shaft 107 has a first chamber R
1, a cam surface having a deepest portion 107a is formed by cutting it into a semicircular shape in cross section. A check arm 111 is arranged below the hydraulic pump P1. The check arm 111 has a first arm portion 111a and a second arm portion 111b extending in different directions,
The midway part is fixed to the support shaft 113, and the support shaft 113 is horizontally extended between the center section 40 and the rear wall 10b of the front case 10 along the longitudinal direction of the machine body, and
11 is swingably supported in the left-right direction. The pin 112 provided on the tip of the first arm portion 111a of the restraining arm 111 contacts the cam surface of the shifter shaft 107, and the tip of the second arm portion 111b contacts one end surface of the restraining pin 114. Has been done. The restraint pin 114 is positioned on the outer surface of the side plate 60 at a substantially intermediate position of the backward speed change rotation range (RB) of the speed control arm 61, and the movable swash plate 53 is tilted by a bush 115 so as to be movable back and forth. A spring 116 is fitted onto the restraining pin 114 located in the first chamber R1 so as to be pivotally supported in parallel with the axis line.
Is urged to retract into the first room R1.

The speed control arm 61, as shown in FIGS. 17 to 20, has a trunnion shaft 53b protruding from the side plate 60.
Is fixed to the tip end of the speed control arm 61, and an abutment portion 61a is provided on the rotation base side of the speed control arm 61.
Is a concave stopper 60 protruding outward from the side plate 60.
It is placed so as to face inside a. The inner dimension of the concave portion of the stopper 60a is set so as to be the maximum forward speed increasing position F and the maximum reverse speed increasing position R of the speed control arm 61 when the abutting portion 61a is rotated and abutted. ing. And
A connecting rod 125 and a telescopic body 126a of the shock absorber 126 are connected to the tip of the speed control arm 61, the connecting rod 125 is connected to the main transmission pedal arranged on the step 4, and the base end 126b of the shock absorber 126 is The telescopic body 126a is pivotally supported on the side surface of the rear case 11 so as to prevent the speed control arm 61 from rapidly rotating.

When the auxiliary transmission lever 7 is operated to the neutral position and the low speed position, as shown in FIG.
12 is located at the deepest portion 107a of the cam surface, the check arm 111 is kept in the illustrated state, and the speed control arm 61 is
Is a stopper 60a as shown in FIGS.
It is possible to rotate in the entire range of the forward gear shift rotation range (FB) and the reverse gear shift rotation range (RB) set by. When the auxiliary shift lever 7 is operated to the high speed position,
Since the shifter shaft 107 is slid forward, the pin 112 provided at the tip of the first arm portion 111a of the restraining arm 111.
Rides on the shallowest part of the cam surface, which causes the check arm 1
8, the second arm portion 111b pushes the end face of the check pin 114 so that the other end of the check pin 114 is projected from the side plate 60. Therefore, the speed control arm 61 is set to the neutral position (see FIG.
When attempting to rotate from 7) to the reverse side, as shown in FIG. 19, when the end face of the speed control arm 61 approaches the intermediate position of the reverse range, the check pin 114 is moved.
Since it hits the outer peripheral surface of the
That is, it is reduced to the reverse rotation shift range (RB ').
In other words, if the auxiliary shift lever 7 is moved backward while being switched to the high speed side, the vehicle reverses at a high speed. Therefore, the high speed reverse traveling state, which is practically unnecessary, is automatically cut and only when the speed is switched to the low speed side. Total rotation range of control arm 61 (RB)
That is why it is possible to accelerate backwards.

Next, the power transmission mechanism for driving the front wheels will be described. As shown in FIG. 2, FIG. 3, FIG. 4, FIG. 5, and FIG. 7, the gear 71 spline-fitted to the front end side on the traveling third transmission shaft 43 is disposed on the front end side of the traveling second transmission shaft 42. It meshes with a rotatably loosely fitted gear 70, and this gear 70 meshes with a gear 72 fixedly mounted on the front wheel drive second shaft portion 44 (FIGS. 3 and 5). As shown in FIG. 3, the front wheel drive shaft is composed of two first shaft portions 13 and a second shaft portion 44, and the front wheel drive first shaft portion 13 penetrates the front wall 10 a of the front case 10. The front wheel drive second shaft portion 44 is rotatably supported in the hole through a bearing, and the front wheel drive second shaft portion 44 is rotatably supported in the rear wall 10b through a bearing, and the axis is aligned with the rear end of the front wheel drive first shaft portion 13. The front end of the front wheel drive second shaft portion 44 is loosely fitted and supported.

A clutch mechanism C for turning on / off the front wheel drive is provided between the front end of the front wheel drive second shaft portion 44 and the rear end of the first shaft portion 13 of the front wheel drive shaft. That is, a spline groove is formed on the outer periphery of each of the front end of the front wheel drive second shaft portion 44 and the rear end of the first shaft portion 13 of the front wheel drive shaft, and is formed on the rear end of the front wheel drive first shaft portion 13. Are spline-fitted so that the slider 73 cannot rotate relatively and can slide in the axial direction. As shown in FIG. 8, the slider 73 has an annular recess 73a formed on the outer periphery thereof with the tip of a shifter 74 being locked,
The shifter 74 is fixed to the inner end of the shifter shaft 75. The shifter shaft 75 is rotatably supported by a side plate 77 fixed to the left outer surface of the front case 10, and a front wheel drive on / off operation arm 76 is fixed to the outer end of the shifter shaft 75 so that the speed of the shifter shaft 75 is increased. It is arranged on the opposite side of the control arm 61. The front wheel drive on / off operation arm 76 is provided with a front wheel drive on / off lever (not shown) provided in a driving section through a link or the like.
Connected with. Note that a ball dedent mechanism is provided between the slider 73 and the front wheel drive first shaft portion 13 so as to hold the slider 73 at the “4WD” position and the “2WD” position.

In such a configuration, when the front wheel drive on / off operation arm 76 is operated to the "4WD" side, the slider 73 causes the front wheel drive second shaft portion 44 and the front wheel drive first shaft portion 13 to move. The power transmitted to the third traveling transmission shaft 43 by engaging the two is transmitted from the gear 71 → the loosely fitted gear 70 → the gear 72 →
Front wheel drive second shaft portion 44 → slider 73 → front wheel drive first shaft portion 13 → universal joint 17 → input shaft 19 →
It is transmitted to the front axle case 18 to drive the front wheels 20, and at the same time, the rear wheels 21 are driven from the traveling third transmission shaft 43 via the differential gear device D, so that four-wheel drive (4
WD). Front wheel drive on / off operation arm 76
When operated to the "WD" side, the slider 73 cuts off power transmission between the front wheel drive second shaft portion 44 and the front wheel drive first shaft portion 13, and only the rear wheel 21 is driven, and two-wheel drive (2WD) is performed.

Next, the PTO transmission will be described. As shown in FIGS. 2, 5 and 6, the rear end of the input shaft 12 penetrates the rear wall 10b of the front case 10 and projects into the second chamber R2. A gear 80 is fixedly mounted on the PTO counter shaft 39, and the gear 80 meshes with a gear 81 fixed on the PTO counter shaft 39. The gear 81 is rotatably loosely fitted on the PTO transmission shaft 33 via a bearing 83. It meshes with the gear 82. A boss portion is provided on the side surface of the gear 82, and as shown in an enlarged view in FIG. 6, the boss portion and a clutch case 84 fixedly mounted on the PTO transmission shaft 33.
The friction plates are alternately interposed between and to constitute a friction multi-plate hydraulically operated PTO clutch 85. When the piston 86 is slid by the hydraulic pressure supply, which will be described later, the friction plate presses the friction plate to engage the gear 82 with the PTO transmission shaft 33 and transmit power from the input shaft 12 to the PTO transmission shaft 33. . Reference numeral 89 denotes a spring that urges the piston 86 in the friction plate pressing release direction.

The front end of the PTO transmission shaft 33 is the front case 1.
0 through the rear wall 10a to project into the first room R1, and the inertial slip prevention brake device G is formed therein. That is, the spline groove 33a is formed on the outer periphery of the front end of the PTO transmission shaft 33, and the spline groove 33a and the front case 1 are formed.
0 friction plates are alternately inserted between the recesses formed in the front surface of the rear wall 10b of 0, and the friction plate at the front end is in contact with the pressing portion 90a formed in the central portion of the disk-shaped actuator 90. . The actuator 90 is provided with a pressing portion 90 protrudingly formed in the central portion thereof and an annular piston portion 90b protrudingly formed in the same direction so as to surround the pressing portion 90a. The piston portion 90b is the friction plate. It is formed to have a larger outer diameter than that of the above, and is inserted into a cylinder chamber formed in a ring shape on the outer periphery of the recess of the rear wall 10b. In this way, the actuator 90 has
By providing b, the size of the actuator 90 in the axial direction is reduced, the overall length of the inertial slip prevention brake device G is shortened, and the transmission is downsized. The actuator 90 is installed on the rear wall 10 of the front case 10.
A spring 88 interposed in a lid 87 fixed to the front surface of b is urged in a direction to press the friction plate.

Oil passages 33b and 33c are bored in the shaft of the PTO transmission shaft 33, and one end of the oil passage 33b opens into a cylinder chamber accommodating the piston 86 of the PTO clutch 85, The other end of the oil passage 33b communicates with an oil passage 10f formed in the rear wall 10b of the front case 10 in the direction of the side plate 77 through an annular groove 33c formed on the outer periphery of the PTO transmission shaft 33. PTO clutch / brake control valve 101 mounted on the side plate 77 through an oil passage 77a formed between the left side surface of the side plate and the side plate 77.
Is connected to the output port of. The PTO clutch / brake control valve 101 is composed of a 3-port 2-position switching type solenoid valve, and is an O switch of a PTO switching switch arranged near the driver's seat.
Switching operation can be performed by N / OFF. Also, the oil passage 10f communicates with the cylinder chamber of the piston portion 90b of the inertial slip prevention brake device G via the oil passage 10c.

The side plate 77 is shown in FIGS. 13, 14, and 1.
5, the oil passage 77a is formed as shown in FIG.
As shown in the right half of 0, it is connected to the accumulator 117. The input shaft 12 is provided in the rear wall 10b of the front case 10.
A cylinder chamber 10d is provided along the direction orthogonal to the cylinder chamber 10d, and a spring 117b and a piston 117a are provided in the cylinder chamber 10d.
Is inserted, the front surface of the piston 117a is covered with the side plate 77, and the front surface is exposed to the oil passage 77a, whereby the accumulator 117 is simply configured. The spring-accommodating side of the cylinder chamber 10d communicates with the bearing chamber 10j of the input shaft 12, and the oil leaked from the gap between the cylinder chamber 10d and the piston 117a during operation of the accumulator 117 lubricates the bearing of the input shaft 12. It has come to be used as oil.

The PTO clutch / brake control valve 101 is disposed above the side plate 77, and the oil passage 77a connected to the output port of the PTO clutch / brake control valve 101 has a clutch attached to the side plate 77. The relief valve 119 for setting the operating pressure is connected, and the relief oil discharged during the operation of the relief valve 119 is the side plate 77.
8 and 12, the oil is sent from the oil passage 10e to the friction plate of the inertial slip prevention brake device G as lubricating oil, and is further flown to the oil passage 77b formed in the joint surface of the front case 10 and the front case 10. , Oil passage 33 bored in the PTO transmission shaft 33
The friction plates and gears of the PTO clutch 85 are lubricated by communicating with c. The input port of the PTO clutch / brake control valve 101 is the side plate 77 and the front case 1.
It is connected to the discharge port of the pressure reducing valve 49 via an oil passage 77c formed at the joint surface with 0 and an oil passage 77e extending in the direction of the center section 40 in the side wall of the front case 10.

With this configuration, when the PTO selector switch is turned on, a part of the oil discharged from the charge pump P2 through the input port and the output port of the PTO clutch / brake control valve 101 is It is supplied to the cylinder chamber of the clutch case 84 from the passage 77c through the oil passage 77a, the oil passage 10f, and the oil passage 33b, and the piston 86 therein is slid in a direction to press the friction plate to engage the PTO clutch 85. The power from the input shaft 12 is transmitted from the gear 82 to the PTO transmission shaft 33 via the clutch case 84. At the same time, the pressure oil that has flowed into the oil passage 10f becomes
The actuator 90 is slid against the spring 88 through 0c to release the braking force of the inertial idle prevention brake device G on the PTO transmission shaft 33. When the PTO switch is turned off, the pressure oil from the oil passage 77c is sent to the oil passage 77d leading to the oil sump in the first chamber R1, and the pressure oil is not sent to the oil passage 10f. Is returned by the urging force of the spring 89, the PTO clutch 85 is disengaged, and the power is not transmitted to the PTO transmission shaft 33.
Since pressure oil is not sent to c as well, the actuator 90
Activates the inertial slip prevention brake device G by the urging force of the spring 88 to stop the rotation of the PTO transmission shaft 33, and
When the TO clutch 85 is disengaged, both rear and mid PTO shafts, which will be described later, are quickly braked to stop all the working machines.

The relationship between the shaft torque acting on the PTO transmission shaft 33 and the time is as shown in FIG.
However, the PTO transmission shaft 3 by the inertial slip prevention brake device G
Brake torque for braking No. 3, P at time (t0)
When the TO changeover switch is OFF, the brake torque having the torque value (T1) acts on the PTO transmission shaft 33. When the PTO switch is turned on, the actuator 90 is pushed by the hydraulic pressure supply, the urging force of the spring 88 is weakened, and the brake torque decreases with the passage of time. On the other hand, until the time (t1), the PTO clutch 85
No transmission torque is generated in the PTO transmission shaft 33 until the cylinder 86 of the piston 86 is filled with hydraulic oil. Then, when the time (t1) is reached, the transmission torque indicated by the waveform b is given to the PTO transmission shaft 33, and the time (t1)-
During (t2), the piston 117a is resisted against the spring 117b.
Is displaced and the hydraulic oil is filled in the cylinder chamber 10d, so that the hydraulic pressure acting on the piston 86 is moderated, and the PTO clutch 85 starts to be gently engaged while gradually increasing the pressing force on the friction plate, thereby reducing the transmission torque. Will rise. Then, when the time (t2) arrives, the displacement of the piston 117a stops, and the piston 86 strongly pushes the friction plate against the biasing force of the spring 89 between the time (t2) and (t3), and the time (t3). ), The PTO clutch 85 is completely engaged, and the set maximum transmission torque T2 is applied to the PTO transmission shaft 33.
Is given.

A mid-PTO drive gear 91 is loosely fitted on the middle portion of the PTO transmission shaft 33, and a spline collar 92 (FIG. 6) is fixed to the rear portion of the PTO transmission shaft 33,
The rear end of the rear transmission shaft 33 is aligned with the rear end of the O transmission shaft 33.
The front end of the transmission shaft 34 connected to the TO drive shaft 35 is loosely supported. An engaging element 93 is formed on the side surface of the mid-PTO drive gear 91, and the engaging element 93 is also formed on the front end of the transmission shaft 34.
4 and a slider 9 on the spline collar 92.
5 is non-rotatable relative to the outside and is slidably fitted in the axial direction. A shifter (not shown) is inserted into an annular recess formed on the outer periphery of the slider 95, and the shifter is fixed to the shifter shaft 122 shown in FIG. The shifter shaft 122 is horizontally slidable in the front-rear direction between the rear wall 10a of the front case 10 and the partition wall 11a of the rear case 11, and its front end faces the first chamber R1. On the other hand, the side plate 77
A switching shaft 124 is horizontally rotatably mounted on the shaft, and an arm 123 is fixed to the inner end of the switching shaft 124.
It is locked to 2. A PTO switching arm 25 is fixed to the outer end of the switching shaft 124, and the PTO switching arm 125 is connected via a link or the like to the PTO switching lever 9 arranged on the driver's seat side.

The mid PTO drive gear 91 is shown in FIG.
As shown in FIG. 4, an idle gear 97 rotatably fitted via a bearing 96 on the axially intermediate portion of the traveling third transmission shaft 43 meshes with the idle gear 97.
Meshes with a gear 98 fixedly mounted on the counter shaft 99, and the gear 98 is a gear 100 fixedly mounted on the mid PTO shaft 14.
And the mid PT drive gear 91
The power is transmitted to the O-shaft 14. In this way, the PT for transmitting power to the mid PTO shaft 14
The O transmission gear train (mid PTO drive gear 91, idle gear 97, gear 98, gear 100) is housed in the second chamber R2 in the housing, and the idle gear 97 is one of the shafts constituting the gear type transmission. Since it is installed here using one, it has a compact configuration.

Therefore, the PTO arranged on the side of the driver's seat
When the switching lever 9 is operated to slide the slider 95 rearward in the plane of FIG. 5, the spline collar 92 and the gear 94 on the transmission shaft 34 are connected via the slider 95, and the power is the PTO transmission shaft. 33 → Spline color 92 →
Slider 95 → engager 94 → transmission shaft 34 → rear PTO
It is transmitted to the drive shaft 35, and only the rear PTO shaft 36 is driven. When the slider 95 is slid forward by one step, the slider 95 moves to the engaging element 9 of the mid PTO drive gear 91.
3, the spline collar 92 and the engagement element 94 of the transmission shaft 34 are connected to drive the above-mentioned rear PTO shaft 36, and the power is PTO transmission shaft 33 → spline collar 92 →
Slider 95 → engager 93 → mid PTO drive gear 9
1, the mid PTO shaft 14 is driven via the PTO transmission gear train, and the mid PTO shaft 14 and the rear PT are driven.
Both O-axes 36 are driven. When the slider 95 is further slid forward, the slider 95 connects only the engaging element 93 of the mid-PTO drive gear 91 to the spline collar 92, and the power is supplied from the PTO transmission shaft 33 → the spline collar 92 → the slider 95 → the engaging element. 93 → Mid PTO drive gear 91 is transmitted, and only the mid PTO shaft 14 is driven.

[0049]

As described above, the present invention has the following advantages. That is, since the first shaft portion of the front wheel drive shaft is rotatably supported in the first room, the first shaft portion of the front wheel drive shaft is irrelevant to the gear-type transmission in the first room in the longitudinal direction of the machine body. The front wheel drive shaft can be laid out at a substantially central position in the lateral direction of the machine body, and the power transmission configuration from the gear type transmission to the front wheel drive shaft can be facilitated. Also, the gear type transmission connected to the output shaft of the hydraulic motor always rotates the front wheels synchronously with the rear wheels regardless of the gear position.

Since the clutch mechanism for engaging and disengaging the front wheel drive shaft and the output portion of the gear type transmission is housed in the first chamber, the front wheel is effectively utilized while utilizing the lower space vacant in the first chamber. Driving / non-driving can be arbitrarily selected.

The front-wheel drive shaft is composed of a first shaft portion and a second shaft portion which are fitted to each other so as to be rotatable relative to each other on the same axis line, and each shaft portion is composed of a front wall and a rear wall constituting the first chamber. While supporting the bearing with the wall, a clutch mechanism that engages and disengages the first shaft portion and the second shaft portion is interposed, while effectively utilizing the space vacant in the first room, The clutch mechanism can be configured simply and compactly.

Since the speed control arm of the hydraulic continuously variable transmission is arranged on one side of the housing and the operation arm of the clutch mechanism is arranged on the other side of the housing, a gear shift operation tool for a driving section and The front wheel drive on / off operation tool can be easily linked without any interference.

When the gear type transmission is switched to the high speed side, a check mechanism is housed in the first chamber to prevent the speed control lever of the hydraulic continuously variable transmission from increasing the speed to the reverse side beyond a certain level. Therefore, the check mechanism can be rationally arranged by effectively utilizing the vacant space in the first room, and it is possible to automatically prevent the reverse state at a high speed which is practically unnecessary. In addition, since the check mechanism is housed in the first room, durability and reliability can be improved for a long period of time.

When the changing operation tool of the gear type transmission is located on the high speed side, a check mechanism is provided in the housing for restricting the speed increasing operation toward the reverse side by the operation tool of the continuously variable transmission. Therefore, foreign matter such as dust, mud, rust, etc. does not hinder the check mechanism, and the check mechanism operates stably and reliably for a long period of time, improving reliability.

The check mechanism is interlocked with the switching operation of the gear type transmission, and the cam means is displaceable in the machine front-rear direction in the first chamber, and the reverse side shift range of the speed control lever on the outer wall surface of the housing. A check pin provided at a predetermined restricting position of which one end side can freely move back and forth toward the speed control lever, and the cam means supported so as to be swingable about the longitudinal axis of the machine body in the first room. Since the check arm is provided with the first arm part that contacts and the second arm part that contacts the other end of the check pin, the check mechanism can be manufactured with a small number of parts and at low cost. became.

Since the portion of the front wall of the housing on which the hydraulic pump and the hydraulic motor are mounted is separable from the housing, the hydraulic continuously variable transmission is assembled and installed in the first chamber. Easy to assemble.

[Brief description of the drawings]

FIG. 1 is an overall side view of a work vehicle.

FIG. 2 is a skeleton diagram of power transmission of a traveling system and a PTO system.

FIG. 3 is a side sectional view of a front case portion.

FIG. 4 Gear-type transmission and mid PTO in the second room
It is a side sectional view showing a power transmission mechanism to a shaft.

FIG. 5 is a side sectional view of the upper part of the housing showing the power transmission mechanism to the front wheel drive shaft and the power transmission mechanism to the rear PTO shaft.

FIG. 6 is an enlarged sectional view of an inertial slip prevention brake device and a PTO clutch.

FIG. 7 is a front view showing an arrangement of power transmission shafts of a traveling system and a PTO system.

8 is a cross-sectional view taken along the line XX in FIG.

FIG. 9 is a plan cross-sectional view of a shift operation portion of the gear type transmission and a reverse shift check device portion linked to the shift operation portion.

10 is a sectional view taken along the line YY on the right side and a sectional view taken along the line Y'-Y 'on the left side in FIG.

FIG. 11 is a front perspective view of the housing.

FIG. 12 is a hydraulic circuit diagram.

FIG. 13 is a left side view of the oil passage plate.

FIG. 14 is a front view of an oil passage plate.

FIG. 15 is a right side view of the oil passage plate.

FIG. 16 is a diagram showing a relationship between shaft torque acting on the PTO transmission shaft and time.

FIG. 17 is a side view showing the check mechanism in which the speed control arm is in the neutral position.

FIG. 18 is a side view showing the check mechanism in which the speed control arm is at the maximum forward acceleration position.

FIG. 19 is a side view showing a check mechanism in which a speed control arm is in a rear speed-up restricting position.

FIG. 20 is a side view showing the check mechanism in which the speed control arm is at the maximum reverse speed increasing position.

[Explanation of symbols]

 C Clutch mechanism P Hydraulic pump M Hydraulic motor 10 Front case 11 Rear case 12 Input shaft 13 Front wheel drive shaft 40 Center section 61 Speed control arm 107 Shifter shaft 111 Checking arm 114 Checking pin

Claims (8)

[Claims] Claim: What is claimed is: 1. A transmission for transmitting engine power to front and rear wheels, wherein a hydraulic continuously variable transmission capable of switching between forward and backward movements and a gear type transmission capable of changing a traveling speed to a plurality of gears are interlockingly connected. In the above configuration, the hydraulic continuously variable transmission is accommodated in a first chamber formed in the housing of the transmission, and the gear type transmission is accommodated in a second chamber. The hydraulic pump and the hydraulic motor constituting the hydraulic continuously variable transmission are separately mounted and fluidly connected to each other on the inner and outer surfaces of the front wall constituting the chamber, and one of the hydraulic pump and the hydraulic motor is connected. The front wheel drive shaft, which is housed in the first chamber and the other is located outside the first part, is rotatably supported in the first chamber while being linked to the gear type transmission. A work vehicle transmission characterized by being projected forward through a wall. 2. The clutch mechanism for engaging and disengaging the front wheel drive shaft with respect to the output portion of the gear type transmission is accommodated in the first chamber. Work vehicle transmission. 3. The front wheel drive shaft is composed of a first shaft portion and a second shaft portion that are relatively rotatably fitted on the same axis line, and each shaft portion is before the first chamber is formed. The work vehicle according to claim 1, wherein a bearing is supported by the wall and the rear wall, and a clutch mechanism for engaging and disengaging the first shaft portion and the second shaft portion is interposed between the first shaft portion and the second shaft portion. Transmission. 4. The speed control arm of the hydraulic continuously variable transmission is arranged on one side of the housing, and the operation arm of the clutch mechanism is arranged on the other side of the housing. A transmission for a work vehicle according to claim 1 or 2. 5. A transmission for transmitting engine power to traveling wheels is linked with a hydraulic continuously variable transmission capable of switching between forward and backward movements and a gear type transmission capable of changing traveling speed to a plurality of gears. In the above configuration, the hydraulic continuously variable transmission is accommodated in a first chamber formed in the housing of the transmission, and the gear type transmission is accommodated in a second chamber. On each of the inner and outer surfaces of the front wall of the room, the hydraulic pump and the hydraulic motor that constitute the hydraulic continuously variable transmission are distributed and mounted and fluidly connected to each other, and one of the hydraulic pump and the hydraulic motor is connected to the first By the speed control lever of the hydraulic continuously variable transmission when the gear type transmission is switched to the high speed side, while the other is located outside the first part while being housed in one room A transmission for a work vehicle, characterized in that a check mechanism for preventing a speed-up operation to a reverse side beyond a predetermined level is accommodated in the first room. 6. The cam mechanism, wherein the check mechanism is interlocked with the switching operation of the gear type transmission, is displaceable in the machine front-rear direction in the first chamber, and the rearward movement of the speed control lever on the outer wall surface of the housing. A check pin that is provided at a predetermined restriction position in the side gear shift range and has one end side that can freely move back and forth toward the speed control lever, and that is swingably supported around the machine longitudinal axis in the first room, It is composed of a check arm including a first arm part that contacts the cam means and a second arm part that contacts the other end of the check pin, and shifts the gear type transmission to a high speed side. The check arm is oscillated so that the second arm pushes the check pin toward the speed control lever when the first arm part rides on the shallow part of the cam means by operation. Work vehicle transmission . 7. A transmission system from an engine to a traveling wheel is provided with a hydraulic continuously variable transmission capable of switching between forward and backward movements and a gear type transmission capable of changing a traveling speed to a plurality of stages. A work vehicle provided with a check mechanism in the housing for restricting a speed increasing operation to a reverse side by a predetermined amount or more by the operation tool of the continuously variable transmission when the change operation tool is located on the high speed side. Transmission. 8. The front wall of the housing, wherein a portion of the front wall on which the hydraulic pump and the hydraulic motor are mounted is configured to be separable from the housing. Work vehicle transmission.