JPS5847591B2 - Power transmission device for agricultural tractors, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a driving power transmission path from a transmission shaft for driving power transmission and working machine power transmission, which is rotationally driven by an engine, to a final traveling 1 drive means. The present invention relates to a power transmission device for an agricultural tractor or the like, which is equipped with a hydraulic clutch type transmission device and a mechanical transmission device for changing driving power.

In other words, agricultural tractors and the like equipped with the above-mentioned hydraulic clutch type transmission device for changing the traveling power can perform speed change operations lightly and easily, and can gradually change the hydraulic pressure applied to the hydraulic clutch in the transmission device. Although the present invention has advantages such as being able to easily obtain a shock-free gear change by increasing the speed, the present invention solves one problem when providing a hydraulic clutch-type traveling power transmission device as described above. At the same time, the existence of the hydraulic clutch type transmission is skillfully utilized to create a power transmission device that has a simple structure and functions similar to a so-called two-stage clutch (dual clutch), and also solves the above-mentioned problems. The purpose is to achieve both the performance of the clutch function without any contradiction, and also to avoid difficulty in shifting operations of the mechanical transmission device downstream of the hydraulic clutch type transmission device.

In an agricultural truck tractor or the like equipped with a hydraulic clutch-type traveling power transmission device, a transmission shaft on which the hydraulic clutch is mounted with the hydraulic clutch transmission device in a neutral state, that is, with all hydraulic clutches in the transmission device in a non-operating state. If all of the upper free-rotating gears are allowed to rotate freely, theoretically the traveling power transmission path is cut off at the hydraulic clutch type transmission part, and the transmission path is transmitted from the operating engine to the final traveling drive means such as the wheels. Or, there should be no transmission of power from the final travel drive means that attempts to automatically rotate on a slope, etc. to the engine that is stopped, but in reality, even in such cases, the engine or final travel drive means A constant rotational torque is transmitted from the drive means to the hydraulic clutch type transmission part,
The friction plates in the hydraulic clutch of the transmission are frictionally engaged with each other with a slight engagement force, and unexpected power transmission occurs in the neutral state of the hydraulic clutch type transmission.

If such a situation occurs, the vehicle may start unexpectedly, which is dangerous.

In addition, the main clutch of agricultural tractors, etc. is configured as a two-stage clutch (dual clutch), and when the main clutch pedal is depressed, if the pedal is depressed one step shallowly, the driving power is cut off, but the PTO continues to rotate. If you want the PTO power to be cut off by depressing the pedal deeply again, the PTO may not stop rotating when replacing gears for gear shifting, or it may take a long time to start rotating to the normal speed due to the large inertial mass. It has advantages such as being able to start rotation of a working machine such as a disc mower that requires rotation before the tractor starts running, and being able to easily do this when it is desired to stop only the tractor running while the working machine continues to be driven. However, it is undeniable that the above-mentioned two-stage clutch has a complicated structure and is expensive.

Based on the above facts, the present invention reliably prevents the above-mentioned unexpected transmission in the neutral state of a hydraulic clutch type transmission for changing traveling power, and utilizes the existence of the hydraulic clutch type transmission. It achieves the same effect as a two-stage clutch with a simple structure, and the mechanisms for this do not conflict with each other, and also do not interfere with the gear shifting operation of the mechanical transmission downstream of the hydraulic clutch type transmission. The purpose is to provide a new power transmission device for agricultural tractors, etc., which does not cause the above problems.

Regarding the illustrated embodiment, to explain the structure of the power transmission device in an agricultural tractor or the like according to the present invention, as shown in FIG. 1 rotates the left and right rear wheels 2, and also drives a working machine (not shown) that is connected to the rear of the machine body via a coupling mechanism (not shown) and is raised and lowered by a hydraulic lift device 3. The PTO shaft 4, which is interlocked and connected to the machine, is rotationally driven by the engine 1, and the machine is steered by an operator sitting on a seat 5 turning the front wheels 7 using a control handle 6. In the constructed agricultural tractor, the present invention is implemented as follows.

That is, the transmission mechanism from the engine 1 to the rear wheels 2 and the transmission mechanism from the PTO shaft 4 in this agricultural tractor are configured as shown in FIG. A connected drive shaft 9 is provided, and between this drive shaft 9 and the rear wheel axle 2a is a traveling power main transmission disposed between one drive shaft 9 and a transmission shaft 10 that is connected to the drive shaft 9. The device 11 includes a drive shaft 9 and a transmission shaft 1.
0 selectively interlockingly connects the transmission shaft 10 to the transmission shaft 10 at an appropriate transmission ratio. A driving power sub-transmission device 13 that is interlockingly connected, a differential device 16 for the left and right rear wheels 2 that is interlockingly connected to the transmission shaft 12 via a bevel gear 14.15 transmission mechanism, and a left and right output shaft 16a of this differential device 16. and a final gear reduction transmission mechanism 17 that interlocks and connects the left and right rear wheel axles 2a to complete a traveling power transmission mechanism, and between the drive shaft 9 and the PTO shaft 4,
A working machine power transmission device 20 is disposed between another drive shaft 19 interlockingly connected to the drive shaft 9 via an intermediate drive shaft 18 and the PTO shaft 4, and is a work machine power transmission device 20 that connects the drive shaft 19 to the PTO shaft 4 at an appropriate speed ratio. The working machine power transmission mechanism is completed through the working machine power transmission system 20 which is selectively interlocked with the work machine power transmission system 20. A transmission, that is, as shown in FIGS. 2 and 3, an F1 transmission gear 21 fitted onto the drive shaft 9;
F2 speed change gear 22, F3 speed change gear 23, and R speed change gear 2
4, F loosely fitted on the transmission shaft 10 and meshed with the corresponding one of the speed change gears 21-24 directly or via the R intermediate gear 24a, an idler gear 25, an F2 idler gear 26, F.
3 idler gear 27 and R idler gear 28, and one friction plate 3
4a to each of the free rotating gears 25-28, and the other friction plate 34b to the transmission shaft 10.
A hydraulic clutch 2 is configured as a multi-disc hydraulic clutch by being supported so as to be slidable only in the direction of the clutch axis.
9-32, pressure oil is supplied to the oil chamber 33c behind the piston 33b slidably provided in the clutch housing 33a, and the piston 33 is moved against the return spring 34c.
The F1 hydraulic clutch 29 is activated by advancing the friction plates 34a and 34b to engage the friction plates 34a and 34b, and selectively connects each of the free rotating gears 25-28 to the transmission shaft 10.
, F2 hydraulic clutch 30, F3 hydraulic clutch 31 and R
The hydraulic clutch 32 is configured as a known hydraulic clutch type transmission.

Hydraulic clutch type traveling power main transmission 11 explained above
be in a neutral state, that is, all hydraulic clutches 2
When 9-3 2 is brought into a non-operating state, the connection between the drive shaft 9 and the transmission shaft 10 is released, and the transmission shaft 10 is supposed to maintain a non-rotating state.

However, the rotational torque transmitted to the drive shaft 9 by the engine 1 or the rear wheel 2 attempting to automatically rotate on a slope etc.
Due to the rotational torque transmitted from the engine to the transmission shaft 10, the friction plates 34a and 34b of the hydraulic clutch are frictionally engaged with a slight engagement force, resulting in an unexpected connection between the engine 1 and the rear wheel 2, which is the final drive means. This may cause the tractor to start unexpectedly.

Therefore, in the illustrated agricultural tractor, first, the above-mentioned transmission shaft 10 is automatically braked with the hydraulic clutch-type traveling power main transmission 11 in a neutral state to prevent the above-mentioned unexpected situation from occurring. The following mechanism is provided.

That is, as shown in FIG. 3, the front end of the transmission shaft 10 extends to the front of the transmission case 35 that accommodates the transmission devices 11, 13, 20, and the transmission shaft 10 extends in the extending portion. A seal housing 36 is fitted on top,
The inner surface of the seal housing 36 and the annular groove on the circumferential surface of the transmission shaft 10 form a plurality of oil chambers 3B, 39, 40, and 41 on the transmission shaft 10, which are sealed from each other by the seal member 31. , the hydraulic oil for operating the hydraulic clutch 2 9-3 2 is once introduced to the oil chamber 3 8-4 1, and then is transferred to the hydraulic clutch 2 9-3 via oil passages 42, 43, etc. drilled in the transmission shaft 10. A brake device 44 for selectively braking the transmission shaft 10 is provided at the end of the extension of the transmission shaft 10.

As clearly shown in FIG. 4, the brake device 44 utilizes a notch flat portion 45 formed in the small diameter portion of the end of the transmission shaft 10 to prevent relative rotation, but to prevent the axis of the shaft 10 from moving. A movable friction brake plate 46 is fitted so as to be slidable along the direction.
It is equipped with

This movable brake plate 46 has friction material affixed to both sides.
The inner surface of the seal housing 36 faces the stepped engagement surface 47 of the seal housing 36, and when the movable brake plate 46 is pushed to the right in FIG. The stationary seal housing 36 restrains the transmission shaft 10 from rotating through the brake plate 46, so that the transmission shaft 10 is braked.

The front end opening of the seal housing 36 is closed by a housing cover 49 fixed to the front end surface of the seal housing 36 by a fixture 48. A piston 50 is disposed in the housing cover 49 with a pin 51 supported by a housing cover 49 inserted into the hole of the piston 50 to prevent it from rotating. An advancing/retracting rod 52 having a large diameter head 52a facing the front is supported so as to be slidable back and forth, and a spring receiver 53 that comes into contact with the end face of the piston 50 is provided on the advancing/retracting rod 52 so as to be slidable back and forth. , this spring receiver 53 and the housing force bar 4
A compression spring 54 is disposed on the advancing/retracting rod 52 between the inner end surfaces of the movable brake plate 46 through the piston 50 to press the movable brake plate 46 against the engagement surface 47 by the action of the spring 54, so that the transmission shaft 10 is braked. It is being done.

The retractable rod 52 is urged to slide in the direction of insertion into the seal housing 36 by another weak compression spring 55 disposed between its head 52a and the inner end surface of the housing cover 49.

The above-mentioned braking of the transmission shaft 10 is performed only when the hydraulic clutch type main transmission for driving power 11 is in the neutral state, and this braking is released when the transmission 11 is in the operating state. This brake release is performed by the hydraulic actuator 50A including the piston 50, that is, by forming an oil chamber 56 in the seal housing 36 behind the peripheral end surface of the piston 50 and supplying pressure oil to the oil chamber 56. The piston 50 resists the force of the spring 54.
This is done by moving the vehicle backwards (forward in the longitudinal direction of the vehicle).

In the illustrated case, the hydraulic pressure for operating the hydraulic clutches 29-32 of the hydraulic clutch-type traveling power main transmission 11 is selectively guided to the oil chamber 56 from the hydraulic oil supply circuit to the clutches and applied thereto. First, a mechanism for supplying and discharging hydraulic oil to and from the hydraulic clutch 2932 will be explained with reference to FIG.

Hydraulic oil for the hydraulic clutches 29-32 is supplied to the main clutch 8 and the drive shaft 9 from the oil tank 57, which also serves as an oil tank 57 in the lower part of the transmission case 35, as shown in FIGS. In between, it is guided into a valve mechanism housing 59 (FIG. 1) on the upper front surface of the mission case 35 by a usual tocoroid type gear pump 58 mounted on the front surface of the mission case 35 and driven by the engine 1. From inside the housing 59, the oil passage in the wall of the mission case 35, the oil passage between the oil passage type plate 60 attached to the front surface of the mission case 35 and the mission case 35, and the oil passage in the seal housing 36 (see above, (not shown) to the oil chamber 38-41 at the end of the transmission shaft 10, and is selectively applied to the hydraulic clutch 2132.

In the valve mechanism housing 59, as shown in FIG. 32, and a switching valve 64 which is inserted into the oil supply circuit 61 and selectively connects the oil supply circuit 61 to one of the hydraulic clutches.

As is clear from FIG. 5, the switching valve 64 is located at a neutral position N1, that is, the hydraulic pressure A neutral position N in which the clutch-type traveling power main transmission 11 is in a neutral state, and a forward first speed position in which only the F1 hydraulic clutch 29 is supplied with oil and oil is drained from the other hydraulic clutches to operate only the F1 hydraulic clutch 29. Oil is supplied only to F1 and F2 hydraulic clutch 30, and oil is drained from other hydraulic clutches.
2nd forward speed position F2 where only the hydraulic clutch 30 is actuated; 3rd forward speed position where only the F3 hydraulic clutch 31 is supplied with oil and oil is drained from the other hydraulic clutches and only the F3 hydraulic clutch 31 is actuated; and R hydraulic position. It is configured as a 5-position switching valve with a reverse position R in which only the clutch 32 is supplied with oil, oil is drained from the other hydraulic clutches, and only the R hydraulic clutch 32 is operated.

Although the configuration of the above-mentioned hydraulic circuit is a usual one, the above-mentioned oil supply circuit 61 also includes an oil supply/drain system that leads to the hydraulic actuator 50A or its oil chamber 56, as shown in FIG. When the switching valve 64 is connected to the operating position F1, F2, F3, and R1, that is, the hydraulic clutch type main transmission 11 is in operation, the pressure regulating valve 63 is connected to the oil supply/discharge circuit 65. The clutch working oil pressure set in is supplied to the oil chamber 56, which causes the piston 50 to retreat and release the braking action of the brake device 44. Conversely, the neutral position N1 of the switching valve 64, that is, the hydraulic clutch When the driving power main transmission 11 is in a neutral or non-operating state, the oil supply circuit 61 is connected to the oil tank 5 via the switching valve 64.
7, the oil is drained from the oil chamber 56 toward the oil tank 57 via the oil supply/drainage circuit 65, and the brake device 44 performs a braking operation.

In the illustrated case, a check valve 66 and a throttle 67 connected in parallel are inserted into the oil supply/discharge circuit 65, as shown in FIG. is from the oil supply circuit 61 to the hydraulic actuator 50A or its oil chamber 5.
When the switching valve 64 is configured to allow oil to flow only in six directions and is switched from its neutral position to its operating position, the oil pressure in the oil supply circuit 61 is rapidly activated via the check valve 66. 50A, the brake device 44
The braking action of the transmission shaft 10 is rapidly released, and the switching valve 6
4 is returned to the neutral position from its operating position, the oil is gradually drained from the oil chamber 56 of the hydraulic actuator 50A through the throttle 67, and the brake device 44 is designed to gradually brake the transmission shaft 10. ing.

Note that the oil supply/drainage circuit 65 described above is connected to the valve mechanism housing 59.
An oil passage (not shown) in the top wall of the mission case 35 and an oil passage (not shown) between the oil passage forming plate 60 and the transmission case 35 are guided from inside to the oil chamber 56. ,
The oil passages 68 and 69 (FIG. 6) in the seal housing 36 are connected to each other.

Since the operating mechanism of the brake device 44 for braking the transmission shaft 10 is configured as described above, when the hydraulic clutch type traveling power main transmission device 11 is placed in the neutral state by changing the position of the switching valve 64, The brake device 44 brakes and restrains the transmission shaft 10 in a non-rotatable manner by the action of a spring 54, brakes and restrains the transmission shaft 10 in a non-rotatable manner in the neutral state, and prevents the transmission shaft 10 from unexpectedly starting the vehicle in the neutral state. Unexpected rotation is reliably prevented, and conversely, when the hydraulic clutch type main transmission 11 is in operation, the brake device 44 is deactivated and the transmission shaft 10 is unbraked. Therefore, the required power transmission via the transmission shaft 10 can be carried out without any problem.

In particular, the switching of the switching valve 64 moves the hydraulic clutch type main transmission 11 from the non-operating state to the operating state. Since the transmission shaft 10 is rapidly released, there is no problem such as the transmission shaft 10 being connected to the drive shaft 9 while the transmission shaft 10 is being braked by the brake device 44, which may cause damage to the transmission member. When moving the driving power main transmission 11 from the operating state to the non-operating state, the transmission shaft 10 is braked gradually by the brake device 44 by the gradual oil drain action through the throttle 67, so that the transmission shaft 10 is rapidly braked. Shocks that can occur in connection with braking, which could also result in damage to the transmission element, are avoided.

As described above, the power transmission device in the illustrated agricultural tractor includes a mechanism that prevents unexpected transmission of power through the hydraulic clutch type transmission 11, which is the main transmission for driving power, when the transmission device 11 is in the neutral state. However, this power transmission device also has two states: a state in which the tractor stops running and only the PTO shaft 4 is rotated and driven, and a state in which both tractor movement and PTO shaft 4 rotation are stopped. ,
A mechanism for selectively obtaining the driving power, that is, a mechanism for obtaining the same effect as a two-stage clutch, is provided as follows by skillfully utilizing the existence of the hydraulic clutch type main transmission 11.

That is, as shown in FIGS. 4 and 6, a high-pressure oil chamber 70 and a low-pressure oil chamber 71 are formed in the housing cover 49 and move back and forth around the advancement/retraction rod 52. Of these, the high-pressure oil chamber 70 70 is the oil passage 68 in the seal housing 36
The low pressure oil chamber 71 is connected to the oil supply circuit 61 for the hydraulic clutch 29-32 by being connected to the oil passage 72 in the housing cover 49.
9, an oil path 74 in the seal housing 36, and an oil path 75 in the oil path forming plate 60
It is connected into a mission case 35 which also serves as a dual purpose.

Also, as shown in FIGS. 4 and 6, the advance/retreat rod 52 has a large diameter portion L that blocks off the oil chambers 70, 72.
1, and a small diameter part L2 which is an arch and an arc continuation of the large diameter part L1, and which communicates the high pressure oil chamber 70 with the low pressure oil chamber 71 when the advancing/retreating rod 52 is pulled out by a slight amount 10 toward the outside of the seal housing 36. It has been formed.

Therefore, when the hydraulic clutch-type traveling power main transmission 11 is in an operating state, when the advancing/retracting rod 52 is pulled out by a slight amount l1, the oil supply circuit 61 is connected to the oil tank 57, and in this way, the oil supply circuit 61 is connected to the oil tank 57. The operating state of the transmission 11, that is, the operating positions F1, F2, F3, and R of the switching valve 64
An unload valve 76 that selectively connects the oil supply circuit 61 to the oil clutch 57 and unloads the hydraulic clutch 2932 of the transmission 11 connects the high pressure oil chamber 70 to the inlet port,
The low-pressure oil chamber 71 is formed as an outlet side port, and the advancing/retracting rod 52 as a spool.As shown in FIG.
and an unloading position ■, and is connected to the oil supply circuit 61.

As described above, when the hydraulic clutch-type traveling power main transmission 11 is in operation, the forward/retractable lever 52 is pulled out by a slight amount l1, and the high-pressure oil chamber 70 is connected to the low-pressure oil chamber 71 through the small diameter portion L2. When the unload valve 76 is displaced to the load action position ■, the oil supply circuit 61
7, the full hydraulic clutches 29-32 are brought into a non-operating state, the transmission 11 is brought to a neutral state, and the traveling of the tractor is stopped.

In this state, if the operation mechanism of the unload valve 76 is linked to the operation mechanism of the main clutch 8 so that the main clutch 8 at the rear of the engine 1 is not disengaged yet, then the operation of the tractor is stopped and the PTO shaft 4 This results in a state in which only the shaft is rotated.

Therefore, in the illustrated agricultural tractor, as will be described later, the advance/retreat lever 52 that controls the spool of the unload valve 76 is replaced by the main clutch pedal 77 which is the operating means of the main clutch 8.
This is related to the above-mentioned advance/retreat rod 52
The main clutch pedal 77 is designed to also function as a mechanical brake release means for the brake device 44, and the main clutch pedal 77
It is related to.

That is, when the advancing/retracting rod 52 is displaced in the direction of pulling out from the housing cover 49, the advancing/retracting rod 52 moves to the fourth and sixth positions.
From the point in time when the reciprocating rod head 52a is displaced by the distance l2 shown in the figure, the head portion 52a of the retractable rod comes into contact with the spring receiver 53, and the spring receiver 53 compresses the compression spring 54 while being displaced together with the retractable rod 52. Therefore,
When the advancing/retracting rod 52 is displaced in the drawing direction by a certain amount l2 or more, the biasing action of the compression spring 54 on the piston 50 is cut off, and the hydraulic clutch type transmission 11 is in a neutral state in which no oil pressure is applied to the oil chamber 56. Also, the spring 54 is connected to the movable brake plate 46 via the piston 50.
By mechanically releasing the energizing action, the braking action of the brake device 44 can be selectively released.

This mechanical brake release means is provided because the above-mentioned mechanical traction power auxiliary transmission 13 is provided after the hydraulic clutch type traction power main transmission 11. The configuration of the device 13 will be explained with reference to FIGS. 2 and 3 again.

As shown in FIGS. 2 and 3, the mechanical running power sub-transmission device 13 has a common boss portion provided on the extension portion 9a of the drive shaft 9 so as to be relatively rotatable via a bearing. Four integral gears 7B, 7 with different diameters
9. Gears 78-81, which are 80 and 81 and are rotated by the transmission shaft 10 by constantly meshing the gear 78 at the frontmost end with a gear 82 formed at the end of the transmission shaft 10, and the drive shaft extension part 9a. Two integral gears 83 and 84 having a common boss portion are provided on the intermediate shaft 85 so as to be rotatable relative to each other through bearings. two gears 86.8
gears 83 and 84 rotated by gear transmission via gears 7 (FIG. 2); one shift gear 88 provided on the transmission shaft 12 so as to be relatively non-rotatable and slidable by spline fitting; Two integral shift gears 89 and 90 having a common boss portion, one engagement piece 91a is attached to the end of the transmission shaft 10, and the other engagement piece 9lb is attached to the shift gear 8.
A dog clutch 91 is provided on each end face of each of the clutches 8 and 8, respectively.

This mechanical running power sub-transmission device 13 selectively slides and displaces the shift gears 8B, 89.90 on the transmission shaft 12, and when the shift gear 90 meshes with the gear 84, the first speed (very low speed) is achieved. ), when the shift gear 90 meshes with the gear 81, it is 2nd speed, when the shift gear 89 meshes with the gear 80, it is 3rd speed, when the shift gear 88 meshes with the gear 79, it is 4th speed, and the shift gear 88 displacement. When the meshing pieces 91a and 9lb are engaged and the meshing clutch 91 is operated, the transmission shaft 12 is rotated by the transmission shaft 10 at the fifth speed.
It is being organized.

As described above, the mechanical traveling power sub-transmission device 13 is the downstream stage of the hydraulic clutch type traveling power main transmission device 11 and has the function of further changing the vehicle traveling speed into five stages. In the case where different transmissions 11 and 13 are installed in series, when the hydraulic clutch type transmission 11 is arranged in the front stage and the mechanical transmission 13 is arranged in the rear stage, the rotational torque is Since the hydraulic clutch type transmission is provided in a smaller part, there is an advantage that the clutches 29-32 can be of small capacity. When operating the driving power sub-transmission device 13,
That is, when the shift gears 88, 89, and 90 are selectively displaced, the shift gear and the gear 79 to be meshed with the shift gears 88, 89, and 90.
, 80, 81 and 84 in the rotational direction, and the relative posture in the rotational direction between the engaging pieces 91a and 9Ib,
If the meshing relationship is not correct and such a relative position is fixed by braking by the brake device 44 of the transmission shaft 10, the gears or meshing pieces on the meshing side that are not in the correct meshing position may become unrotatable. Due to the restriction, the above-mentioned speed change operation becomes extremely difficult.

Therefore, in the power transmission device shown in the figure, when the mechanical running power sub-transmission device 13 is operated to change speed, by releasing the braking of the transmission shaft 10 by the brake device 44, the meshed side gear and the meshing piece can be rotated. Even if the gear or the meshing piece is not in the correct meshing position in a certain state, it is pushed in the rotational direction by the shift gear displacement and rotates slightly, so that meshing can be easily achieved. It is.

As mentioned above, the advance/retreat lever 52 is provided as a mechanical brake release means for this purpose, and the advance/retreat lever 52
2 constitutes the spool of the unload valve T6, as described above, and the advance/retreat lever 52 is connected to the main clutch pedal 77 by operating the pedal 77 in the direction of disengaging the main clutch 8, that is, by depressing the pedal. The unloading valve 76 is associated with the advancing/retracting rod 52 so that it can be displaced in the direction of withdrawal from the seal housing 36.
The amount of displacement l1 of the forward/backward lever that causes the brake to unload is smaller than the amount of displacement l2 of the forward/backward lever that releases the braking action of the brake device 44 (l1<l2), and when the main clutch pedal 77 is depressed. Hello, first unload valve 7
6 is caused to perform an unloading operation, and then the braking action of the brake device 44 that performs a braking action is mechanically released by releasing the hydraulic action on the oil chamber 56 accompanying the unloading action. .

Next, the related mechanism between the advancement/retraction lever 52 and the main clutch pedal 77 in the illustrated case will be explained in FIGS. 7 and 8 and 3.4.
6, a stopper metal fitting 92 that contacts the outer end surface of the cover 49 outside the housing cover 49 is fixed to the base end of the advancing/retracting rod 52 supported by the housing force bar 49 to seal the advancing/retracting rod 52. The amount of inward protrusion into the housing 36 is regulated, and a pin 93 that protrudes in the left-right direction is fixedly provided on the stopper hardware 92.

The clutch housing 94 in front of the transmission case 35 has a rotating shaft 95 that extends through the side wall of the housing 94 and is rotatable around its axis. A rotating metal fitting 96 having a pair of protrusions 96a that abuts the pin 93 from the rear end side of the vehicle is fixed to the pin 93.

Therefore, when rotating the rotating shaft 95 in the direction of the arrow S in FIG.
The stopper hardware 92 is displaced in the direction in which the advancing/retracting rod 52 is pulled out.

As shown in FIG. 7, the main clutch 8 is a conventional friction plate type mechanical clutch, and its disengagement is performed by rotational displacement of a rotating metal fitting 97 that operates a clutch disengagement cam. As shown in FIG. 7, between this rotating hardware 97 and the main clutch pedal 77 is a rotating tube 98 on the rotation fulcrum shaft of the pedal 77, which is rotated around the axis by the rotation of the pedal 17. A cylinder 98, an arm 99 protruding from the rotating cylinder 98, a connecting rod 100, and a rotating arm 1 that is rotatable around a rotating fulcrum shaft 101 that is common to the rotating hardware 97.
02, the main clutch pedal 77 is depressed via the rotating arm 102 which is interlockingly connected to the arm 99 via the connecting rod 100, and the rotating fulcrum shaft 101 which is rotatably supported around the axis. The rotating metal fittings 97 are connected in an interlocking manner so that the rotating hardware 97 is rotationally displaced in the direction of disengaging the main clutch 8. Similarly, as shown in FIG. An arm 103 separate from the arm 99 is provided protruding from the cylinder 98, and between this arm 103 and the rotating shaft 95, a rotating arm 104 fixed to the end of the rotating shaft 95, and an arm 103, When the main clutch pedal 77 is depressed, the rotating cylinder 98 and the arm 1
03, the rotating hardware 96 is designed to be rotated in the direction of extracting the advancing/retracting rod 52 via the connecting rod 105, the rotating arm 104, and the rotating shaft 95.

And in the middle of the above series 100 and 105, respectively,
Adjustment mechanisms 100a and 105a are provided to adjust the lengths of the connecting rods 100 and 105 to adjust the timing of disengagement of the main clutch 8 and the timing of withdrawal of the advancing and retracting rods 52. By depressing the main clutch pedal 77, the advance/retreat lever 52 is first pulled out to the unload operating position of the unload valve 76 before the main clutch 8 is disengaged. The main clutch 8 is disengaged at the same time as the advancing/retracting lever 52 is pulled out to a position where the braking action of the clutch 44 is released.

Therefore, when working with the agricultural tractor shown in the figure, if you wish to stop only the tractor running and continue driving the work equipment, depress the main clutch pedal 77 slightly and the unload operation of the unload valve 76 will be applied. By connecting the oil supply circuit 61 to the oil tank 57, the hydraulic clutch type main transmission for driving power 11 is brought into a non-operating or neutral state, and the driving power transmission path is cut off at the transmission 11 to obtain the above state. In this state, due to the connection of the oil supply circuit 61 to the oil tank 57, the hydraulic action on the oil chamber 56 of the hydraulic actuator 50A is released, and the brake device 44 brakes the transmission shaft 10. Since the braking action is taken, it is possible to prevent the tractor from unexpectedly starting while the vehicle is in the stationary work state or in the stationary work state.

Furthermore, when the agricultural tractor shown in the figure is used for work or simply traveling, when the mechanical traveling power sub-transmission device 13 is to be operated to change gears, the main clutch 8 is disengaged and the main clutch 8 is disengaged. When depressing the main clutch pedal 77 deeply to disengage the clutch 8,
Since the advancing/retracting rod 52 is pulled out to a large extent to compress the compression spring 54 and release the braking action of the brake device 44, the transmission shaft 10, and therefore the speed change gear on the drive shaft extension 9a, are also in a state where they can freely rotate. This allows the mechanical transmission 13 to be shifted extremely easily.

In addition, a compression spring 54 is attached to the outer periphery of the tip of the advancing/retracting rod 52.
In addition, since the aforementioned compression spring 55 is provided, when the main clutch 8 is engaged, when the foot is released from the main clutch pedal 77 and the pedal is returned to its original position by the spring, the spring 55 acts to move the advancing/retracting rod 52 to the position shown in the figure. When the main clutch pedal 77 is depressed, only the force of the spring 55 acts upon the unloading operation of the unload valve 76, and the force of the spring 54 acts upon the subsequent braking of the brake device 44. Since the depression resistance of the pedal 77 is considerably different when it is released and when the main clutch 8 is disengaged, it is possible to accurately detect when only the unload valve 76 is activated.

As shown in FIG.
107, 108, 109, and three shift gears 110, 111, 112 spline-fitted to the PTO shaft 4,
A mechanical transmission includes an idler gear 113 loosely fitted to the PTO shaft 4 and meshed with the speed change gear 106 on the drive shaft 19, and a dog clutch 114 interposed between the shift gear 110. Due to selective displacement of cars 110-112 on PTO shaft 4, actuation of dog clutch 114 causes 1
2nd speed gear ratio due to meshing between gears 108 and 110, 3rd gear gear ratio due to meshing between gears 107 and 111,
The meshing between the gears 106 and 112 provides a four-speed gear ratio, and is configured to interlock the drive shaft 19 and the PTO shaft 4, respectively.

In FIG. 2, reference numeral 115 denotes a brake for the left and right rear wheels 2 provided at the end of the differential output shaft 16a.

In the above embodiment, the unload valve 76 selectively connects the oil supply circuit 61 that supplies hydraulic oil to the hydraulic clutches 29-32 of the hydraulic clutch type transmission 11 to the oil pump 57, and the braking of the brake device 44 is installed. The mechanical brake release means 52 for releasing the brake is made of a common component, and is interlocked and connected to the main clutch pedal 77 by a common interlocking connection mechanism, but when doing so, the structure is extremely simplified. Although the present invention is not limited to such a configuration, it is possible to provide the above-mentioned unload valve and brake device in separate parts and use separate interlocking coupling mechanisms. A power transmission device configured to be interlocked and connected to the main clutch operating means via the
It is included in that scope.

FIG. 9 shows another embodiment constructed in this way, in which the unload valve 76 is not provided in the housing cover 49 and a similar unload valve (see FIG. (not shown) is provided in the valve mechanism housing 59, and the advance/retreat lever 52, which is a mechanical brake release means of the pre-1000 device 44, is interlocked and connected to the main clutch pedal 77 in the same manner as described above, and A rotating shaft 120 for displacing the spool or rotor of the unload valve is connected to the upper extension 9 of the arm 99 on the rotating cylinder 98.
9a, a connecting rod 1 including a connecting rod 121, a bell crank 122 rotatable around a fulcrum 122a, and a length adjustment part 123a.
23 and the rotating arm 124, so that when the main clutch pedal 77 is depressed, the unload valve is first operated to unload before the brake device 44 is released and the main clutch 8 is disengaged. I'm trying.

Further, in the above embodiment, the brake device 44 for braking the transmission shaft 10 performs the braking action by the action of the spring 54, and selectively performs the braking action depending on whether the hydraulic actuator 50A and the mechanical brake release means 52 fall. A movable brake plate 46 that supports the brake device 44 to be released on the end of the transmission shaft 10 in a slidable but non-rotatable manner and is pressed against a fixed case surface 47. However, such a brake device also includes a brake disc 1 fitted to the extending end of the seal housing 36 of the transmission shaft 10, as shown in FIG. 10, for example.
30 and a brake band 131 wrapped around the brake disc 130, which is brought into pressure contact with the disc 130 by the biasing action of a spring 132, and by the hydraulic action on the oil chamber 134 of a hydraulic actuator 133, or by sliding. Rod 1
The brake device 129 can also be configured with a brake band 131 that can be selectively loosened by the pushing action of the first
The oil chamber 134 shown in FIG. When released, the transmission shaft 10 is automatically braked by the action of the spring 132, and even when only the traveling power is cut off due to the unloading operation of the unloading valve as described above due to shallow depression of the main clutch pedal 77, the oil is supplied to the oil chamber 134. When the hydraulic pressure is released, the transmission shaft 10 is automatically braked, and when the main clutch 8 is disengaged due to deep depression of the pedal 77, the above-mentioned braking is released.

In addition, a brake device for ensuring that the traveling power transmission path is cut off when the hydraulic clutch type transmission 11 is in a neutral state includes:
As described above, in addition to disposing it on the transmission shaft 10 of the hydraulic clutch type transmission 11, it can also be arranged on another transmission shaft at a later stage, for example, the transmission shaft 12 described above. 10 is also in a braked relationship, so it may be provided on another transmission shaft as described above.

As is clear from the above description, the power transmission device of the agricultural tractor or the like of the present invention is configured such that the transmission shaft 9, which is rotated and driven by the engine 1 and is used for both traveling power transmission and working machine power transmission, is connected to the final traveling drive. In an agricultural tractor or the like, in which a hydraulic clutch type transmission 11 and a mechanical transmission 13 for changing the traveling power are arranged in a traveling power transmission path leading to 1,000 gears 2 and are provided in series in this order. A brake device 44, 129 is provided on the transmission shaft 10 of the hydraulic clutch type transmission 11 or a transmission shaft at a later stage in the power transmission path, and brakes the transmission shaft by the action of a spring 54, 132. , this brake device 44, 129 is provided with a hydraulic actuator 50A for releasing the brake against the action of the spring 54, 132,
133 and mechanical brake release means 52, 135 are attached so that the braking action by the brake devices 44, 129 can be released independently of each other, and the hydraulic clutch 29-3 in the hydraulic clutch type transmission 11 is provided. An unload valve 76 is provided to selectively connect the oil supply circuit 61 that supplies hydraulic oil to the oil tank 57 to the oil tank 57, and the mechanical brake release means 52, 135 and the unload valve 76 are connected to the main engine at the rear of the engine. At step 7T of operation for engaging and disengaging the clutch 8, by operating step T1 of operation in the direction of disengaging the main clutch 8, first the unload valve 76 is operated to unload, and then the braking operation of the brake device 44, 129 is activated. The main clutch 8 is interlocked and connected so that it is released and the main clutch 8 is disengaged, and has the following advantages.

■ When the hydraulic clutch transmission for traveling power is in a neutral state, the friction plates of the hydraulic clutches in the hydraulic clutch transmission are unexpectedly moved together due to torque transmission from the engine or the final traveling drive means to the transmission part. engaged with;
An unexpected start of the vehicle is automatically prevented by the brake device that automatically performs a braking operation in the neutral state.

■ With a shallow operation of the main clutch operating means, the unloading operation of the unload valve brings the hydraulic clutch type transmission into a neutral state, cutting off the traveling power, and this operation prevents the main clutch from being disengaged. Because of this, it is possible to stop only the running of the tractor, etc. and continue driving the work equipment, and furthermore, by operating the main clutch operating means deeply, it is possible to disengage the main clutch and obtain the driving and stop of the work equipment. , the same effect as a two-stage clutch can be achieved without employing a two-stage clutch with a complicated structure.

■ When the tractor, etc. stops running and the work equipment continues to be driven, the hydraulic actuator for releasing the brake system is deactivated by the unloading operation of the unload valve, and the brake system automatically performs the braking operation. In the same way as in the case, unexpected vehicle starts are prevented, and although the two-stage clutch function is provided, this point serves other purposes such as preventing unexpected vehicle starts when the hydraulic clutch type transmission is in the neutral state. There are no contradictions, and they are beautifully compatible.

■ Moreover, even though a brake device is provided to achieve the actions described in ■ and ■, a mechanical brake release means is provided and is activated in conjunction with the main clutch disengagement to release the braking action of the brake system. Therefore, there is no difficulty in shifting the mechanical transmission after the hydraulic clutch type transmission.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of an agricultural tractor equipped with an embodiment of the present invention, FIG. 2 is a mechanical diagram showing the power transmission mechanism of the same tractor, FIG. 3 is a vertical side view of the main parts of the tractor, and FIG. The figures are: Fig. 3 is an enlarged vertical side view showing an enlarged part of the illustrated portion; Fig. 5 is a circuit diagram showing the hydraulic circuit installed in the tractor; Fig. 6 is a Vl-
FIG. 7 is a cross-sectional plan view taken along line VI, FIG.
A longitudinal partial view taken along the line ■-■ in the figure, Fig. 9 shows another embodiment, a partially cutaway and partially longitudinal side view similar to Fig. 7, and Fig. 10 shows another embodiment. FIG. 1... Engine, 2... Rear wheel (final drive means), 4... PTO shaft, 8... Main clutch, 9...・Drive shaft, 10...Transmission shaft, 11...Hydraulic clutch type traveling power main transmission, 12...Transmission shaft, 13...Mechanical drive Power sub-transmission device, 18... intermediate drive shaft,
19... Drive shaft, 20... Working machine power transmission, 29... F, Hydraulic clutch, 30...
...F2 hydraulic clutch, 31...F3 hydraulic clutch, 32...R hydraulic clutch, 36.
... Seal housing, 44 ... Brake device, 45 ... Flat part, 46 ... Movable friction brake plate, 47 ... Stepper Amen, 49・
...Housing cover, 50...Piston, 50A...Hydraulic actuator, 52...
...Advancing/retracting rod, 52a...Large diameter head, 53.
... Spring holder, 54 ... Compression spring,
55... Compression spring, 56... Oil chamber, 59... Valve mechanism housing, 61...
...Oil supply circuit, 64...Switching valve, 65...
...Oil supply and drainage circuit, 70...High pressure oil chamber, 71...
...Low pressure oil chamber, L1...Large diameter section, L2...
...Small diameter part, 76...Unload valve,
77... Main clutch pedal, 92...
Stopper hardware, 93...Pin, 94...
...Clutch housing, 95...Rotation shaft, 9
6...Rotating hardware, 96a...Protrusion,
97... Rotating hardware, 98... Rotating tube,
99... Arm, 100... Continuous rod, 1
02... Rotating arm, 101... Rotating fulcrum shaft, 103... Arm, 104...
・Rotating arm, 105... Link, 120...
...Rotation axis, 121...Connection rod, 122...
...Bell crank, 123...Running rod, 129
... Brake device, 130 ... Brake disc, 131 ... Brake band, 13
2...Spring, 133...Hydraulic actuator, 134...Oil chamber, 135...
...Sliding rod.

Claims (1)

[Claims] 1. A hydraulic clutch type transmission device for changing the traveling power, which is arranged in the traveling power transmission path from the transmission shaft for traveling power transmission and working machine power transmission, which is rotated and driven by the engine, to the final traveling drive means. and a mechanical transmission are arranged in series in this order on the transmission shaft of the hydraulic clutch type transmission or a transmission shaft at a subsequent stage thereof, in the traveling power transmission path, in an agricultural tractor or the like, in which the A brake device that brakes the transmission shaft by a spring action is provided, and a hydraulic actuator and a mechanical brake release means for releasing the brake against the spring action are provided in the brake device. An unload valve is provided so as to be able to release the action independently of each other, and an unload valve is provided to selectively connect an oil supply circuit for supplying hydraulic oil to the hydraulic clutch in the hydraulic clutch type transmission to an oil tank, The mechanical brake release means and the unload valve are connected to the operating means for engaging and disengaging the main clutch at the rear of the engine, and by operating the operating means in the direction of disengaging the main clutch, the unloading valve is first operated to unload, and then the unloading valve is operated to unload. A power transmission device characterized in that the main clutch is interlocked and connected so that the braking action of the brake device is released and the main clutch is disengaged.