JPH05178107A - Front wheel accelerating mechanism of farm tractor - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the sudden switching state from the front wheel accelerating speed to the front wheel standard speed by interposing a throttling mechanism in a hydraulic circuit of a hydraulic friction clutch to avoid sudden engagement. CONSTITUTION:A throttling mechanism S is interposed between a solenoid switching valve K and a hydraulic friction clutch 47. The throttling mechanism S is adapted to perform the throttling operation both in the case of supplying pressure oil to the hydraulic friction clutch 47 and in the case where the pressure oil from the hydraulic friction clutch 47 returns from a drain circuit. Especially, in the case where pressure oil in the hydraulic friction clutch 47 is deflated so that a sliding clutch tooth 48b is returned by an energizing spring 48b, the return of the sliding clutch tooth 48b is delayed so that the engagement between the sliding clutch tooth 48b and an engagement tooth 48qc is gradually performed so as to avoid shock.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front wheel speed-increasing mechanism switching mechanism for improving a standard speed and a turning performance of a front wheel speed in a four-wheel drive mechanism in a tractor mission mechanism.

[0002]

2. Description of the Related Art Conventionally, a technique relating to a front wheel speed increasing mechanism of an agricultural tractor has been publicly known. For example, it is as disclosed in Japanese Patent Publication No. 3-62569 and Japanese Patent Publication No. 2-42688.

[0003]

SUMMARY OF THE INVENTION The present invention solves the problems of the conventional front wheel speed increasing mechanism for agricultural tractors. Especially, since the front wheel standard speed is used more frequently than the front wheel acceleration speed, the side that is likely to be used at all times is the articulated mechanical clutch, and the front wheel acceleration speed side is In the case of a hydraulic friction clutch, the impact bite of the bite type mechanical clutch at the time of switching is eliminated. Further, the electromagnetic switching valve for operating the hydraulic friction clutch is constructed in a small size and is fitted and embedded in the wall portion of the mission so as not to occupy a mounting place. Further, different clutch mechanisms of the articulation type mechanical clutch and the hydraulic friction clutch are compactly configured and can be arranged at the bottom of the mission case.

[0004]

The problems to be solved by the present invention are as described above. Next, the means for solving the problems will be described. That is, the power connecting / disconnecting mechanism on the front wheel standard speed side is configured in the articulating mechanical clutch 48, and the power connecting / disconnecting mechanism on the front wheel increasing speed side is configured by the hydraulic friction clutch 47, and the articulating mechanical clutch is connected to the front wheel standard speed side. The biasing spring 48a is constantly biased in the direction in which 48 engages, and the hydraulic friction clutch 47
In the hydraulic circuit of the hydraulic friction clutch 47, the throttle mechanism S is installed in the hydraulic circuit of the hydraulic friction clutch 47 in order to avoid the impact occlusion in the forward hydraulic clutch 31 that shifts from the speed increasing side to the standard side by the biasing spring 48a. It is a costume.

Further, the front wheel speed increasing mechanism of the agricultural tractor in which the power connecting / disconnecting mechanism on the front wheel standard speed side is constituted by the occlusal mechanical clutch 48 and the power connecting / disconnecting mechanism on the front wheel speed increasing side is constituted by the hydraulic friction clutch 47. The electromagnetic switching valve K for controlling the pressure oil to the hydraulic friction clutch 47 is fitted and fixed in the wall pressure of the transmission case.

Further, the front wheel speed increasing mechanism of the agricultural tractor in which the power engaging / disconnecting mechanism on the front wheel standard speed side is constituted by the occlusal mechanical clutch 48 and the power engaging / disengaging mechanism on the front wheel speed increasing side is constituted by the hydraulic friction clutch 47. In the above, the sliding piston of the hydraulic friction clutch 47 is used as the articulation tooth of the articulation type mechanical clutch 48, and the biasing spring 48a for constantly biasing the articulation type mechanical clutch 48 is interposed.

[0007]

[Operation] Next, the operation will be described. That is, in the present invention, the front wheels can be driven to perform four-wheel drive traveling,
In the case of normal road traveling, the front wheel standard speed is transmitted via the power transmission mechanism constituted by the articulated mechanical clutch 48. And, like the circulation at the end of the field,
When the peripheral speed of the front wheels becomes faster, the front wheels are switched to the speed-increasing speed to improve the steering and enable turning with a small turning radius. The switching between the standard speed of the front wheels and the acceleration speed of the front wheels is performed by automatically switching the electromagnetic switching valve by turning the steering wheel at a certain angle or more.

[0008]

EXAMPLES Next, examples will be described. FIG. 1 is a skeleton diagram showing the overall configuration of the mission mechanism of the agricultural tractor of the present invention. Referring to FIG. 1, a hydraulic clutch type main transmission mechanism will be described. Power is transmitted from the engine E to the input shaft 65 via the main clutch, the input gear 11 at the rear end of the input shaft 65 is inserted into the transmission case, and loosely fitted on the main transmission hydraulic clutch shaft 66. It meshes with the first speed gear 12. The first speed gear 12 meshes with the first speed driven gear 16 on the main transmission shaft 67. Similarly, the second speed gear 13 on the main speed change hydraulic clutch shaft 66 is the second speed drive gear 17 on the main speed change shaft 67, and the third speed gear 14 is the third speed drive gear 18.
The fourth speed gear 15 meshes with the fourth speed drive gear 19. The first speed gear 12 drives the main speed changing hydraulic clutch shaft 66 by connecting the first speed hydraulic clutch 26, and the second speed gear 13 drives the main speed changing hydraulic clutch shaft 66 by connecting the second speed hydraulic clutch 27. Reference numeral 14 drives the main shift hydraulic clutch shaft 66 by connecting the third speed hydraulic clutch 28 to drive the fourth speed gear 15
Drives the main shift hydraulic clutch shaft 66 by connecting the fourth speed hydraulic clutch 29.

Next, the PTO shift will be described. The first speed driven gear 16 and the second speed drive gear 17 on the main transmission shaft 67
The third speed drive gear 18 and the fourth speed drive gear 19 are the PTO
A PTO fourth speed gear 20, a PTO third speed gear 21, a PTO second speed gear 22, and a PTO first speed gear 2 on the speed change shaft 68.
It meshes with 3. Then, the PTO shift slider 103
The 4th and 3rd speed of the PTO can be obtained by the forward and backward movement of the. Also P
By moving the TO shift slider 102 back and forth, PTO second speed and first speed are obtained. Further, the fourth speed drive gear 19 meshes with the PTO reverse rotation gear 25 on the PTO reverse rotation gear shaft 74,
The reverse rotation gear 25 meshes with the reverse rotation driven gear 24 on the PTO transmission shaft 68, and the PTO reverse rotation slider 101 slides to rotate the PTO transmission shaft 68 in reverse. The PTO speed change shaft 68 is transmitted to the PTO shaft 62 by a coupling,
It projects to the rear of the mission case. The PTO shaft 62 drives the tiller claw shaft 53 from the bevel gear box shaft 54 of the rotary tiller.

Next, a hydraulic clutch type forward and backward transmission mechanism will be described. The reverse gear 32 is loosely fitted to the rear end of the main shift hydraulic clutch shaft 66, and the reverse gear 32 is rotated by the engagement of the reverse hydraulic clutch 30 to rotate the reverse counter shaft 7
It is meshed with the gear 33 on the upper part 3. The reverse counter shaft 7
The gear 34 at the end of No. 3 meshes with the gear 36 of the creep shaft 71. The reverse rotation is transmitted by the gear train. In the case of forward movement, the rotation of the main shift hydraulic clutch shaft 66 is transmitted to the gear 35 by the engagement of the forward hydraulic clutch 31, and the gear 35 is directly meshed with the gear 36 on the creep shaft 71. Therefore, the forward rotation is transmitted.

Next, the creep transmission mechanism will be described. The speed change slider 10 is supported on the creep counter shaft 70 on which the gear 35 is fixed, and the speed change slider 10 slides forward to integrate the creep counter shaft 70 and the auxiliary speed change shaft 72. As a result, the creep high speed is transmitted to the auxiliary transmission shaft 72, and the transmission slider 10 moves to the gear 38.
The low creep speed is transmitted from the gear 35 through the gear 36, the creep shaft 71, and the gear 37 to the sub-transmission shaft 72 by being integrated with the side.

Next, the auxiliary transmission mechanism will be described with reference to FIGS. 1 and 6. 6 is a side sectional view showing a part of the auxiliary transmission mechanism and the front wheel speed increasing mechanism, and FIG. 7 is a side sectional view of the front wheel speed increasing mechanism portion. The creep shaft 7 is attached to the gear 38 on the auxiliary transmission shaft 72.
The creep low speed from No. 1 is transmitted, and the creep high speed is transmitted by the transmission slider 10 integrating the creep counter shaft 70 and the auxiliary transmission shaft 72. Sub-transmission shaft 7
The transmission gears 39 and 40 are loosely fitted to the upper part of the drive gear 2, and the driven gears 41 and 42 are mounted on the drive pinion shaft 61.
Always meshes with. Then, by operating the shift slider 59, a high / low shift of the sub shift can be obtained. The rotation after the sub-shift is from the pinion 50 to the ring gear 5 of the differential gear device 56.
It is transmitted to 5. The gear 57 on the differential side shaft meshes with the gear 58 on the axle to drive the rear wheel 51.

Next, the front wheel drive transmission mechanism will be described with reference to FIGS. 1 and 7. The driven gear 41 on the drive pinion shaft 61 is always meshed with the front wheel drive gear 43 on the front wheel drive shaft 63, and the front wheel power is taken out only when the drive pinion shaft 61 rotates. A front wheel speed-up drive gear 44 and a front wheel standard drive gear 45 are fixedly mounted on the front wheel drive shaft 63. Front wheel speed-up drive gear 4
4 is a front wheel high speed driven gear 4 on a front wheel shift counter shaft 64.
6, the front wheel standard drive gear 45 meshes with the front wheel standard driven gear 49 on the front wheel shift counter shaft 64.
Then, the front wheel standard driven gear 49 is connected to the front wheel shift counter shaft 6
4 and a hydraulic friction clutch 47 that joins the front wheel speed-increasing driven gear 46 to the front wheel shift counter shaft 64.

In FIG. 7, the articulating mechanical clutch 48
Is composed of a biasing spring 48a, a sliding clutch tooth 48b, and an engaging tooth 48c of a front wheel standard drive gear 49. The sliding clutch teeth 48b also serve as the sliding piston of the hydraulic friction clutch 47. The hydraulic friction clutch 47 is composed of a piston that is also used by the sliding clutch teeth 48b, a clutch friction plate 47b, and a clutch cylinder 47a.

That is, when pressure oil is supplied between the clutch cylinder 47a and the sliding clutch teeth 48b, the sliding clutch teeth 48b move to press the clutch friction plate 47b, and the hydraulic friction clutch 47 is moved. When the pressure oil in the clutch cylinder 47a is released, the sliding type clutch teeth 48b are moved to the occlusal teeth 48c side of the front wheel standard driven gear 49 by the pressing force of the biasing spring 48a, and the sliding type Clutch teeth 4
The engagement state of 8b and the interlocking tooth 48c occurs, and the mechanical clutch portion 48 and the front wheel standard driven gear 49 mesh with each other. The front wheel shift counter shaft 64 has a front wheel drive clutch 60.
Power is transmitted from the front wheel intermediate shaft 69 to the front wheel 52 by the forward and backward movement of the.

FIG. 2 is an enlarged side view of the transmission case of the PTO gear shift lever 97 and the shifter first shaft 75 / shifter second shaft 76 / shifter third shaft 77, and FIG. 3 is the front mission case M1 and center plate. 7 is a side view of the mounting portion of the electromagnetic switching valve K provided at the joint between the rear transmission case M2, FIG. 4 is a front sectional view of the rear transmission case M2 of the mounting portion of the electromagnetic switching valve K, and FIG. FIG. 8 is a front sectional view of the valve K, and FIG. 8 is a hydraulic circuit diagram of the transmission mechanism of the tractor of the present invention.

FIG. 2 shows the PTO gear shift lever 97 and the three shifter shaft portions. Since the PTO speed change mechanism obtains the fourth speed shift and the reverse rotation, the PTO speed change slider has three positions 103, 102 and 101 as shown in FIG.
This PTO speed change slider 103
Three shifters for operating 102/101 are also engaged with 78/79/80. The shifter 78 is a shifter first shaft 7
5, the shifter 79 is fixed to the third shifter shaft 77, and the shifter 80 is fixed to the second shifter shaft 76.

The shifter first shaft 75 is connected to the shift lever engaging body from the connecting link 105 via the lever 59, the lever shaft 92 and the arm 96 at the rear end. Shifter second shaft 7
Reference numeral 6 is connected to a shift lever engaging body from a connecting link 106 at its rear end via a lever 88, a lever shaft 91 and an arm 94. Further, the shifter third shaft 77 is connected to the shift lever engaging body from the connecting link 104 via the lever 90, the lever shaft 93 and the arm 95 at the rear end. By selectively engaging the three shift lever engaging bodies with the PTO shift lever 97 and rotating them forward and backward, PTO shifts of the fourth speed and the reverse rotation are performed.

Next, the hydraulic circuit will be described with reference to FIGS. 8, 4 and 5. Electromagnetic switching valve K that constitutes a main part of the present invention
Is fitted and fixed to the wall portion of the front rear mission case M2 of the PTO gear shift lever 97. Then, it reaches the electromagnetic switching valve K on the wall portion of the rear mission case M2. The pressure oil from the hydraulic pump on the side of the engine is sent through the external pipe 99. Further, the pressure oil controlled by the electromagnetic switching valve K is also sent by the external pipe 119 to the seal case at the end of the front wheel shift counter shaft 64 on which the hydraulic friction clutch 47 is installed.

The electromagnetic switching valve K comprises a pilot valve 100 which is slid by a solenoid 98, and a front wheel switching spool 6 which slides by switching the oil passage by the pilot valve 100. The front wheel switching spool 6 and the pilot valve 100 are pierced through holes in the wall of the rear mission case M2, and the solenoid 98 is located outside the rear mission case M2. A signal from a changeover switch provided on the steering handle is electrically transmitted to the solenoid 98.

According to the present invention having the above-described structure, the electromagnetic switching valve K and the hydraulic friction clutch 4 shown in FIG.
The diaphragm mechanism S is interposed between the seven. The throttle mechanism S performs a throttle action even when pressure oil is supplied to the hydraulic friction clutch 47, and the hydraulic friction clutch 47
Even when the pressure oil from the hydraulic circuit returns from the drain circuit, the throttling action is performed. In the present invention, however, the pressure oil in the hydraulic friction clutch 47 escapes, and the sliding clutch teeth 48b move the biasing spring 48a. When it is returned by, the return of the slidable clutch teeth 48b is delayed, and the slidable clutch teeth 48b are delayed.
The effect is exerted in that the occlusal teeth 48c are gradually occluded to avoid an impact.

In FIG. 3, the rear mission case M
2, the electromagnetic switching valve K, and the external pipe 99 are disclosed. Further, a front wheel drive clutch lever 120 is arranged at the rear of the electromagnetic switching valve K, and the front wheel drive clutch 60 is turned ON-O via a link 121 and an arm 123.
It is FF. In FIG. 8, the entire hydraulic circuit of the tractor will be described. A horizontal control cylinder 116 and an automatic control valve 124 of the working machine mounted on the rear part of the tractor are arranged, and a working machine lifting hydraulic switching valve V for controlling the lifting cylinder 115 of the working machine is arranged.

Further, the hydraulic clutch 26.2 of the main transmission mechanism
A main speed change operation valve 2 for controlling 7/28/29 and a forward / reverse speed change operation valve 3 for controlling hydraulic clutches 30/31 of the forward / reverse speed change mechanism are interposed. In addition, the traveling operation cylinder 11
A steering valve 117 for switching the steering wheel 8 by operating the steering wheel is provided.

[0024]

Since the present invention is configured as described above, it has the following effects. That is, since it is configured as in claim 1, since there is no abrupt switching when shifting from the front wheel acceleration speed side to the front wheel standard speed side, it is shocked to switch from the front wheel acceleration speed to the front wheel standard speed. The situation does not occur. Further, it is possible to eliminate the unpleasant vibration and noise during the engagement between the sliding clutch teeth 48b and the occlusal teeth 48c.

Since the electromagnetic switching valve K can be embedded in the wall portion of the mission case, the valve case is not required and the electromagnetic switching valve portion greatly projects from the mission case. Is gone. Further, by connecting the external pipe 99 to the processed hole of the mission case, the external pipe portion can be minimized. Further, unlike the conventional case, the valve case portion is no longer fixed to the transmission case with bolts, so that the solenoid 98
It is possible to reduce the malfunction of the front wheel switching spool 6. Further, since the electromagnetic switching valve K is inserted and arranged in a component having a large heat radiation capacity such as a mission case, it is possible to avoid a temperature rise in the valve portion.

According to the third aspect of the invention, since the portion of the clutch cylinder 47a can be inserted into the cylinder of the front wheel standard driven gear 49, the length on the front wheel shift counter shaft 64 of the front wheel speed increasing mechanism can be increased. It was possible to make the length shorter. Since the sliding clutch teeth 48b can also be used as the piston of the hydraulic friction clutch 47, the front wheel speed increasing mechanism can be made simple and compact.

[Brief description of drawings]

FIG. 1 is a skeleton diagram illustrating an overall configuration of a mission mechanism of an agricultural tractor according to the present invention.

[Fig. 2] PTO gear shift lever 97 and shifter first shaft 75
FIG. 7 is an enlarged side view of a mission case of a shifter second shaft 76 / shifter third shaft 77.

FIG. 3 is a side view of a mounting portion of an electromagnetic switching valve K provided at a joint portion of a front mission case M1, a center plate 7 and a rear mission case M2.

FIG. 4 is a front cross-sectional view of a mission case M2 at the rear of the mounting portion of the electromagnetic switching valve K.

5 is a front sectional view of an electromagnetic switching valve K. FIG.

FIG. 6 is a side sectional view showing a part of an auxiliary transmission mechanism and a front wheel speed increasing mechanism.

FIG. 7 is a side sectional view of a front wheel speed increasing mechanism portion.

FIG. 8 is a hydraulic circuit diagram of the speed change mechanism of the tractor of the present invention.

[Explanation of symbols]

 K Electromagnetic switching valve S Throttling mechanism M2 Rear transmission case 6 Front wheel switching spool 47 Hydraulic friction clutch 47a Clutch cylinder 47b Clutch friction plate 48 Interlocking mechanical clutch 48a Energizing spring 48b Sliding clutch tooth 48c Interlocking tooth 98 Solenoid 99, 119 External piping 100 Pilot valve

Claims (3)

[Claims] 1. A front wheel standard speed side power connection / disconnection mechanism is constituted by an occlusal mechanical clutch 48, and a front wheel speed increase / speed side power connection / disconnection mechanism is constituted by a hydraulic friction clutch 47, and the front wheel standard speed side is occluded. In the forward hydraulic clutch 31 in which the urging spring 48a is constantly urged in the direction in which the mechanical mechanical clutch 48 is engaged, the pressure oil of the hydraulic friction clutch 47 is released, and the urging spring 48a shifts from the speed increasing side to the standard side. A front wheel speed-increasing mechanism for an agricultural tractor, wherein a throttle mechanism S is provided in a hydraulic circuit of a hydraulic friction clutch 47 in order to avoid an impact bite. 2. A front wheel speed-increasing mechanism for an agricultural tractor in which the power connecting / disconnecting mechanism on the front wheel standard speed side is constituted by an articulated mechanical clutch 48, and the power-disconnecting mechanism on the front wheel speed increasing speed side is constituted by a hydraulic friction clutch 47. At the hydraulic friction clutch 47
A front wheel speed-increasing mechanism for an agricultural tractor, characterized in that an electromagnetic switching valve K for controlling pressure oil to the engine is fitted and fixed in the wall pressure of the mission case. 3. A front wheel speed-increasing mechanism for an agricultural tractor in which the power connecting / disconnecting mechanism on the front wheel standard speed side is constituted by an articulated mechanical clutch 48, and the power-disconnecting mechanism on the front wheel speed increasing side is constituted by a hydraulic friction clutch 47. At the hydraulic friction clutch 47
The front wheel speed-increasing mechanism for an agricultural tractor, wherein the sliding piston is used as an occlusal tooth of the articulating mechanical clutch 48, and a biasing spring 48a for urging the articulating mechanical clutch 48 toward the joining side is interposed.