JPS6114910Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is based on self-propelled working vehicles such as agricultural tractors, speed sprayers, and wheel loaders (hereinafter referred to as ``agricultural tractors, etc.'') that are equipped with a hydraulic clutch type transmission device for changing driving power. The present invention relates to a power transmission device in which the agricultural tractor or the like is driven at a slow speed and starts at a low acceleration as necessary.

In other words, when using an agricultural tractor, etc., when moving the tractor, etc. in a narrow place such as a ridge, it is difficult to perform the work unless it is driven at a slow speed, or when the tractor, etc. is stored in a warehouse, garage, etc. When the agricultural tractor, etc. is required to travel at very low speed, or when positioning is to be performed at very low speed before performing stationary work using a working machine such as a pest control machine driven by a PTO shaft, On the other hand, when running at very low speed is required or desirable, for example, when fragile items such as glass products are loaded onto an agricultural tractor, or when starting a tractor on a slippery road such as snow. In such cases, when loading the tractor, etc. onto a transport vehicle or when starting the tractor, etc., the agricultural tractor, etc. is started at low acceleration, and the above-mentioned cases may occur due to rapid start-up. It is necessary or desirable to have a smooth start that avoids inconveniences such as damage to objects due to shock or slipping of the tractor, but conventional methods have been used to start agricultural tractors at slow speeds or at low accelerations. The following measures were taken.

In other words, in agricultural tractors, etc., the main clutch, which is located immediately after the engine in the direction of power transmission and is disengaged by depressing the main clutch pedal, is slip-engaged by adjusting the amount of depressing the main clutch pedal. As a result, the vehicle was running at very low speed or starting at low acceleration. It has also been proposed to use a brake and clutch together; for example,
The publication describes a selector that controls the supply and discharge of hydraulic pressure to a hydraulically operated forward/reverse clutch device located immediately after the engine and torque converter in the direction of power transmission in conjunction with the depression of the brake pedal that operates the brakes. The valve is displaced toward the neutral position, and the oil supply path to the forward/reverse clutch device is throttled by the selector valve, the hydraulic pressure applied to the forward/reverse clutch device is reduced, and the clutch device slips into engagement. , a transmission is disclosed which allows the vehicle to run at a slow speed or start at a low acceleration by simultaneously applying the brake and slipping the clutch.

However, as described above, the operation of adjusting the amount of depression of the main clutch pedal or brake pedal to obtain a half-clutch state, a half-brake state, or a half-clutch state requires skill and is an operation that is accompanied by mental fatigue. Moreover, it relies on the intuition of the operator, and there is poor reproducibility of obtaining a constant slow vehicle speed or low starting acceleration. When performing work while moving at a slow speed, or when removing snow by attaching a snow blower to a tractor and moving the tractor at a slow speed, it is possible to obtain steady vehicle running at a slow speed by using the pedals as in the conventional example described above. Adjusting the amount of depression operation causes significant fatigue to the operator and is almost impossible in practice. Moreover, because of the above, it is almost impossible to change and control the obtained slight vehicle speed or low starting acceleration.

The purpose of this invention, as mentioned at the beginning, is to create a simple structure that skillfully utilizes the hydraulic clutch type transmission for agricultural tractors and the like that are equipped with a hydraulic clutch type transmission for changing the traveling power. To provide a new driving power transmission device that is capable of not only starting a vehicle at a low acceleration but also allowing the vehicle to run at a steady slow speed while eliminating the problems of the conventional devices described above. be.

Regarding the illustrated embodiment, the structure of the power transmission device in an agricultural tractor or the like according to this invention will be explained. As shown in FIG. The working machine rotates the left and right rear wheels 2 and drives a working machine (not shown) which is connected to the rear part of the machine body via a connecting mechanism (not shown) and is raised and lowered by a hydraulic lift device 3. The PTO shaft 4, which is interlocked with the PTO shaft 4, is rotationally driven by the engine 1, and the aircraft is steered by an operator sitting on a seat 5 turning the front wheels 7 using a control handle 6. This idea was implemented in the agricultural tractor developed in the following way.

That is, as shown in FIG. 2, the transmission mechanism from the engine 1 to the rear wheels 2 in this agricultural tractor includes a drive shaft 9 interlockingly connected to the engine 1 via a main clutch 8, and a drive shaft 9 parallel to the drive shaft 9. A traveling power transmission 11 disposed between the transmission shafts 10 that selectively interlocks and connects the transmission shaft 10 to the drive shaft 9 at an appropriate speed ratio; A traveling power sub-transmission device 13 selectively interlocks and connects the other transmission shaft 12 disposed to the transmission shaft 10 at an appropriate gear ratio, and a driving power sub-transmission device 13 that selectively interlocks and connects the other transmission shaft 12 arranged therein to the transmission shaft 10 at an appropriate gear ratio; Differential device 16 for left and right rear wheels 2, and this differential device 16
The final gear reduction transmission mechanism 17 interlocks and connects the left and right output shafts 16a and the left and right rear wheel axles 2a. The traveling power main transmission 11 described above is a hydraulic clutch type transmission as follows, that is, an _F1 speed change gear 18, an _F2 speed change gear 19, an _F3 speed change gear 20, and an R speed change gear fitted to the drive shaft 9. A speed change gear 21, an F ₁ idle gear 22, an F ₂ idle gear 23, which are loosely fitted to the transmission shaft 10 and meshed with the corresponding one of the speed change gears 18-21 either directly or via the R intermediate gear 21a. The _F3 idler gear 24 and the R idler gear 25, one friction plate is attached to each of the above idler gears 22-25, and the other friction plate is attached to the transmission shaft 1.
A hydraulic clutch 26- is configured as a multi-plate hydraulic clutch by being supported by a clutch housing that is fixed at 0 so that it can only slide freely in the direction of the clutch axis.
29, _F1 hydraulic clutch 26, _F2 hydraulic clutch 27, which are actuated by the engagement between the friction plates by pressure oil action and selectively couple each of the idler gears 22-25 to the transmission shaft 10; , an F ₃ hydraulic clutch 28 and an R hydraulic clutch 29, it is constructed as a hydraulic clutch type transmission known per se.

The hydraulic oil supply and discharge control for the hydraulic clutches 26 to 29 in the above-mentioned hydraulic clutch-type traveling power main transmission 11 is performed using a hydraulic circuit as shown in FIG. Hydraulic oil is supplied to the hydraulic clutches 26-29 by a hydraulic pump 32 interposed between the main clutch 8 and the drive shaft 9 from an oil tank 31 constructed using the lower part of the system case 30 (Fig. 1). The oil supply circuit 33 that supplies oil and whose oil pressure is set by the pressure regulating valve 34 has a neutral position N and a forward second speed position where only the _F1 hydraulic clutch 26 is actuated.
The switching valve 3 has five positions: F ₂ , F ₃ , a forward third speed position F ₃ that operates only the hydraulic clutch 28 , and a reverse position R that operates only the R hydraulic clutch 29 .
5, a branch circuit 36 leading from the oil supply circuit 33 toward the oil tank 31 is connected to a hydraulic circuit 36 as shown in FIG. , a non-operating position N that blocks the branch circuit 36, and an unloading operating position UL that drains the hydraulic oil from the oil supply circuit 33 while squeezing it toward the oil tank 31. Throttle unload valve 37 for clutches 26-29
is inserted and provided.

This throttle unload valve 37 is connected to a valve mechanism housing 38 on the upper surface of the mission case 30, which has a built-in pressure regulating valve 34 and a switching valve 35 shown in FIG.
(Fig. 1), and has a structure as shown in Fig. 4. That is, this throttle unload valve 37 is
9, at the front and rear of the spool 40 in the length direction, a high pressure oil chamber 42 is always connected to the oil supply circuit 33 via a pump port 41, and a high pressure oil chamber 42 is always connected to the oil tank 31 via a tank port 43. The low pressure oil chamber 44 is configured to have a low pressure oil chamber 44 in a similar relationship. And the above spool 4
0, both oil chambers 42,
44 _, and a small diameter portion _L2 that continues from _the large diameter portion _L1 . When pulled out _one or more times, the notch 45 that communicates the high pressure oil chamber 42 with the low pressure oil chamber 44 is gradually moved toward the tip of the spool 40.
The notched groove 45 has a large cross-sectional area and is formed over a distance l ₂ . and spool 40
The spool 4 has both ends received by its large diameter head 40a and the spring receiving wall 46 of the valve case 39.
It is biased to move in the direction of entering the valve case 39 by a first compression spring 47 provided on the valve case 39, and also comes into contact with the case lid 39a of the valve case 39 to restrict its most advanced position. When the spool 40 is pulled out by approximately a distance _l1 , the large diameter head 40a of the spool 40
A movable spring receiving ring 48 is provided on the spool 40, and a second compression spring 49 is provided on the spool 40 between the movable spring receiving ring 48 and the spring receiving wall portion 46. , when the spool 40 is pulled out by a distance l ₁ or more, the spring 49 is compressed to significantly increase the resistance to pulling out the spool 40.

As described above, when the spool 40 is pulled out by the amount ₁₁ or more while the hydraulic clutch type main transmission for traveling power is in operation, and the high pressure oil chamber 42 is connected to the low pressure oil chamber 44 via the notched groove 45, oil flows from the high pressure oil chamber 42 to the low pressure oil chamber 44 via the notched groove 45.
A small percentage of oil is drained in the direction from the oil supply circuit 33 to the oil tank 31, so that the oil pressure in the high pressure oil chamber 42, and therefore the oil pressure in the oil supply circuit 33, drops below the oil pressure set in the pressure regulating valve 34. As a result, the hydraulic clutch 26-2
The hydraulic pressure acting on the hydraulic clutch 26, 27, 28 or 29 is reduced, and the hydraulic clutch 26, 27, 28 or 29 in the operating state is
When the hydraulic clutch is in a half-clutch state, the pressure between the friction plates of the transmission shaft 10 and the clutch plate 9 is reduced, and the hydraulic clutch is operated in a slipping manner to obtain a half-clutch state, so that the rotational speed of the transmission shaft 10 is significantly reduced. The degree of this reduction in rotational speed can be adjusted as desired by adjusting the amount of pull-out of the spool 40 within the range of the length _l2 of the notched groove 45.

Then, as shown in Figures 4 and 5, the spool 4
At the base end of the valve case 39, there is a stopper metal fitting 50 that comes into contact with the outer end surface of the case 39 outside the valve case 39.
is fixed with a split pin 51 to restrict the amount of movement of the spool 40 inward to the case 39.As shown in FIGS. An operating pin 52 is fixedly provided. And in the valve mechanism housing 38,
A rotating shaft 53 that protrudes outward from the side of the housing and is rotatable around an axis is supported, and a tip of the rotating shaft 53 is attached to the operating pin 52 at the rear end of the vehicle within the housing 38. Contact from the direction 1
A rotating metal fitting 54 having a pair of protrusions 54a is fixed. Therefore, the rotation axis 53 is aligned with the arrow S in FIG.
When rotating in the direction, the shaft 53
The protrusion 5 of the rotating hardware 54 rotates around the axis of the
4a pushes the operating pin 52 to displace the stopper hardware 50 in the direction of pulling out the spool 40, and as described above, the operating lever 55 rotates the rotating shaft 53 and pulls out the spool 40. is fixed to the rotating shaft 53 at its base end.

As shown in FIG. 2, the traveling power sub-transmission device 13 described above includes a series of speed change gears 56, 57, 5 that are loosely fitted into the extension 9a of the drive shaft 9.
8, 59, and are rotated by the transmission shaft 10 by meshing the gear 60 on the drive shaft extension 9a, which rotates in conjunction with the gears 56-59, with the gear 61 at the end of the transmission shaft 10. -59, three shift gears 62, 63, 64 spline-fitted to the transmission shaft 12, and a meshing clutch 65 between the transmission shafts 10, 12, which is activated by the displacement of the shift gear 64. consists of a transmission,
By selectively displacing the shift gears 62-64 on the transmission shaft 12, the meshing between the gears 56 and 62 provides a 1st speed gear ratio, the meshing between the gears 57 and 62 provides a 2nd speed gear ratio, and the meshing between the gears 58 and 63 provides a 2nd speed gear ratio. The transmission gear shafts 10 and 12 are selectively interlocked and connected, respectively, with a 3rd gear gear ratio when the teeth 59 and 64 engage, a 4th gear gear ratio when the teeth 59 and 64 engage, and a 5th gear gear ratio when the engagement clutch 65 operates. It's a big deal. In FIG. 2, reference numeral 66 indicates a brake for the left and right rear wheels 2 provided at the end of the differential output shaft 16a.

As described above, when using the agricultural tractor shown in Fig. 1-5, if the tractor is required or desired to run at a low speed as mentioned at the beginning, the throttle unload valve is operated by operating the lever 55. 1 hydraulic clutches 26, 27, 28 which are in an operating state according to the position of the switching valve ₃₅ while adjusting the throttle unload amount within the range of the distance _l2 . or 29
By performing slip operation to obtain a half-clutch state, it is possible to variably adjust and obtain the above-mentioned slow speed running. Furthermore, if the above-mentioned half-clutch state is obtained by operating the lever 55 before starting this agricultural tractor, the acceleration when starting the tractor can be reduced, so as mentioned at the beginning, the tractor's acceleration can be reduced. If a low acceleration start is required or desired, the low acceleration start can be obtained by doing as described above. Note that when the spool 40 is pulled out by l ₁ amount or more, the spool 4 is pulled out by the action of the second compression spring 49.
0 pullout resistance, and therefore the operating resistance of the operating lever 55 increases significantly, so the throttle unload valve 3
7 from the non-operating position N to the unloading position UL can be accurately determined.

Next, another embodiment shown in FIGS. 6 and 7 will be described. In this embodiment, as shown in FIG.
A branch circuit 36 that connects 3 toward the oil tank 31
A switching valve 70 having a position for blocking the circuit 36 and a position for releasing the blocking, and a low pressure relief valve 71 are inserted in series in this order. Both valves 70 and 71 are connected to the seventh valve.
As shown in the figure, it is constructed in one piece. To explain in more detail, a common valve case 72 is provided for both valves 70 and 71,
A pump port 73 connected to the oil supply circuit 33 and a tank port 74 in contact with the oil tank 31 are formed in this valve case 72, and the pump port 73 is opened at the base end inside the valve case 72. There is a distance l between the first oil chamber 75 and the oil chamber 75.
A spool having a large diameter portion L ₁ and a subsequent small diameter portion L ₂ forming a second oil chamber 76 disposed at the front side and normally blocking the space between the two oil chambers 75 and 76. 77 is inserted into the valve case 72 from the proximal end side. Further, a valve body 78 of the low pressure relief valve 71 is inserted into the tip of the valve case 72.
The midway longitudinally long small diameter portion 78a position and the valve body 78
The second oil chamber 76 is communicated with the oil chamber 79 at the tip through an oil passage 80 bored in the valve case 72 . Then, due to the hydraulic action on the oil chamber 79, the seventh
When it is moved back to the position shown by the imaginary line in the figure,
The valve body 78, which performs a relief operation by communicating between the oil passage 80 and the tank port 74 via the outer periphery of the small diameter portion 78a, is disposed within the valve case 72 with both ends received by the valve body 78 and the spool 77. It is urged to move in the forward direction by a compression spring 81,
The compression spring 81 is adapted to function as a pressure setting spring for the low pressure relief valve 71.

As above, the spool 77 is moved by the distance l ₁
If you pull it out more than that, the outer circumference of the small diameter part _L2 will cause the
The second oil chambers 75 and 76 are brought into communication, and the switching valve 70 is moved from position to position,
The low pressure relief valve 71 is connected from the pump port 73 through the first oil chamber 75, the second oil chamber 76, and the oil passage 80.
Pressure oil flows into the valve and the relief valve 71 performs a relief operation, but when the spool 77 is pulled out as described above, the gap between the spool 77 and the valve body 78 is expanded and the compression spring 81 is expanded. Therefore, the force applied by the spring 81 to the valve body 78 is small. Therefore, the force of the valve 81 can be adjusted by adjusting the amount by which the spool 77 is pulled out, for example, within the distance _l2 shown in FIG. However, the set pressure or relief pressure of the low pressure relief valve 71 can be adjusted within this range.
In the illustrated case, the spool 77 is pulled out by rotationally displacing a pinion 83 that engages with a rack 82 formed at the base end of the spool 77 using a control lever 84. The determined relief pressure of the low pressure relief valve 71 is:
It is set to a value gradually lower than the clutch working pressure set in the pressure regulating valve 34, and at this relief pressure, the friction plates of the hydraulic clutches 26-29 slip into engagement with each other, so that the spool 77 The low hydraulic pressure regulated by the drawer is applied to one hydraulic clutch 26, 27, 28 or 29 in operation to obtain a slip operation or half-clutch condition of the clutch, and as in the previous embodiment, the vehicle is operated. This allows the vehicle to selectively run at very low speeds and start at low accelerations.

Next, another embodiment shown in FIG. 8 will be described. In this embodiment, the end of the pressure setting spring 90 of the pressure regulating valve 34 is received by a movable spring receiver 91 that changes the force of the spring 90 by its displacement. , this movable spring receiver 91 is received by a screw rod 93 that moves forward and backward via a nut member 93a that is rotationally displaced by an operating lever 92, and when the screw rod 93 retreats, the movable spring receiver 91 is retreated, and the hydraulic clutch 26-29 The set pressure of the pressure regulating valve 34 can be lowered to a low oil pressure at which a slit operation of 100 mL can be obtained.In this case, the setting pressure of the pressure regulating valve 34 is also lowered to allow for selection as in both of the previous embodiments. This allows the vehicle to run at very low speeds and start at low acceleration. That is, the eighth
The embodiment illustrated in the figures includes a multi-disc hydraulic clutch 26-
Pressure regulating valve 34 for setting the normal working oil pressure for 29
is provided in a branch circuit branched from the oil supply circuit 33 and led toward the oil tank 31,
The pressure regulating valve 34 is provided with a function of lowering the clutch operating oil pressure in the same way as the throttle unload valve 37 and the low pressure relief valve 71, so that the pressure regulating valve 34 is also used as a pressure reducing valve means.

As is clear from the above description, the traveling power transmission device for an agricultural tractor or the like of this invention is provided with a hydraulic clutch type transmission 11 for changing the traveling power. Hydraulic oil supply circuit 3 for multi-disc hydraulic clutches 26, 27, 28, 29
A branch circuit branched from 3 and led toward the oil tank 31 is provided, and levers 55, 84,
Pressure reducing means 37, 7 which can be activated by 92 operation
0,71,34, pressure reducing valve means 37, 70 for reducing the hydraulic pressure applied to the multi-plate hydraulic clutches 26, 27, 28, 29 and slip-engaging the multi-disc hydraulic clutches 26, 27, 28, 29; ,7
1, 34, and this pressure reducing valve means 37, 70, 7
1 and 34 are configured as valves that can change and adjust the degree of pressure reduction set therein by operating the levers 55, 84, and 92 described above, and have the following advantages. .

That is, the traveling power transmission device of this invention is constructed as described above, and is capable of obtaining a half-clutch state of the hydraulic clutch as necessary to cause a tractor, etc. to travel at a slow speed and start at a low acceleration. , low-speed running and low-acceleration starting that are often required for agricultural tractors, etc.
This is made possible by a simple mechanism using a hydraulic clutch type transmission.

Moreover, since the traveling power transmission device of this invention obtains slip engagement of the hydraulic clutch in the hydraulic clutch type transmission device by the pressure reducing valve means operated by the levers 55, 84, and 92, By operating a lever whose operation position is clearly known to a specific position, steady vehicle running at a slow speed can be achieved with constant reproducibility, and operation does not require skill and does not cause fatigue. This is useful not only for things that do not grow, but also for plowing or other work while moving the vehicle at slow speeds in narrow areas such as along the edges of rows or between crop rows, or by attaching a snow blower to the tractor and removing snow while moving the tractor at slow speeds. This allows the vehicle to run at a constant slow speed when performing work without imposing a burden on the worker.

Furthermore, in the traveling power transmission device of this invention, the above-described pressure reducing valve means 37, 70, 71, and 34 are configured as valves that can change and adjust the degree of pressure reduction by operating the levers 55, 84, and 92. The obtained slight vehicle speed and low starting acceleration can be controlled with high accuracy by using a lever whose operating position is clearly visible.
When carrying out agricultural work with a vehicle such as a tractor running at a slow speed in a narrow space in a field, it is possible to easily and precisely change and control the vehicle speed within a range of slow speeds depending on the crop condition or field situation. It is also possible to easily and precisely change and control the vehicle speed within the range of slight vehicle speeds in response to changes in the amount of snow during snow removal operations.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view of an agricultural tractor equipped with an embodiment of this invention, Fig. 2 is a mechanical diagram showing the power transmission mechanism in the same tractor, Fig. 3 is a circuit diagram showing the hydraulic circuit of the same embodiment, Fig. 4 is a longitudinal sectional side view of the main parts, Fig. 5 is a longitudinal sectional front view of only the main parts along the - line in Fig. 4, Fig. 6 is a hydraulic circuit diagram of another embodiment, and Fig. 7 is a longitudinal sectional side view of the main parts. FIG. 8 is a longitudinal cross-sectional side view of the main parts of another embodiment, and FIG. 8 is a hydraulic circuit diagram of another embodiment. 1...engine, 2...rear wheel, 9...drive shaft,
10... Transmission shaft, 11... Hydraulic clutch type traveling power main transmission, 26, 27, 28, 29... Hydraulic clutch, 33... Oil supply circuit, 34... Pressure regulating valve,
35...Switching valve, 36...branch circuit, 37...throttle unload valve, 40...spool, 41...
... Pump port, 42 ... High pressure oil chamber, 43 ... Tank port, 44 ... Low pressure oil chamber, 45 ... Notch groove, 50 ... Stopper hardware, 52 ... Operation pin, 53 ... Rotation shaft, 54... Rotating hardware, 54a
... Protrusion, 55 ... Operation lever, 70 ... Switching valve, 71 ... Low pressure relief valve, 73 ... Pump port, 74 ... Tank port, 75 ... First oil chamber, 76 ... Second Oil chamber, 77...Spool, 7
8... Valve body, 80... Oil path, 81... Compression spring,
92...Rack, 83...Pinion, 84...Control lever, 90...Pressure setting spring, 91...Movable spring receiver, 92...Control lever, 93...Screw rod.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. In an agricultural tractor or the like equipped with a hydraulic clutch type transmission for changing driving power, a circuit for supplying hydraulic oil to a multi-disc hydraulic clutch in said hydraulic clutch type transmission, A branch circuit leading toward the oil tank is provided, and a pressure reducing valve means is provided in the branch circuit which can be actuated by operating a lever to reduce the hydraulic pressure applied to the multi-disc hydraulic clutch and slip engage the multi-disc hydraulic clutch. A traveling power transmission device characterized in that a pressure reducing valve means is provided, and the pressure reducing valve means is configured as a valve whose degree of pressure reduction can be changed and adjusted by operating the lever described above. 2. The pressure reducing valve means is provided with a movable adjusting body which is interlockingly connected to the lever and is displaced in a direction that increases the degree of pressure reduction by the pressure reducing valve means by operating the lever in the direction in which the pressure reducing valve means operates. A traveling power transmission device according to claim 1, which is a utility model.