JPS6231708Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a traveling drive device for running agricultural tractors and the like that are attached with various working machines and used for various agricultural works, etc., and is equipped with a hydraulic clutch type transmission for changing the traveling power. The present invention relates to a type of traveling drive device.

Agricultural tractors, etc. can be used for cutting trenches in fields by pulling trenchers, removing snow in orchards, vegetable gardens, etc. with a snow removal machine attached, removing snow on roads with a snow blower attached, During various other tasks, vehicles are required to run at extremely low speeds, or in other words, creep. The vehicle speed during creep driving depends on the type of work being done, the condition of the field, etc.
The optimal vehicle speed varies depending on the amount of snowfall, etc.

On the other hand, creep drive mechanisms installed in traveling vehicles such as agricultural tractors have conventionally been generally selected by using a creep drive mechanism, as disclosed in, for example, Japanese Utility Model Application No. 53-149183 and Japanese Utility Model Application No. 54-1830. It is equipped with a gear reduction mechanism that can take part in the transmission of running power, and has been attached to a gear shift type running power transmission. Such a creep driving mechanism keeps the vehicle speed constant during creep driving, or only allows for changes in two stages at most, and if it were to be possible to change the speed in multiple stages, it would be expensive and bulky. .

What can be considered here is the well-known hydraulic transmission system (hydraulic transmission system), which is a variable displacement hydraulic pump and a fixed displacement hydraulic motor connected by a pair of hydraulic supply and discharge circuits that form a closed circuit together with the pump and motor. A static transmission (static transmission) is installed in the driving power transmission path, and this hydraulic transmission device controls changes in vehicle speed even in the creep driving range, allowing the vehicle to creep by continuously changing the vehicle speed during creep driving. To obtain a creep traveling speed suitable for the type and conditions of work when performing various works while traveling. However, an attribute of a hydraulic power transmission device is that when the swash plate angle of the variable displacement hydraulic pump is changed to a small one such as 2 degrees or 3 degrees and the volume is reduced, the amount of oil leak from the hydraulic pump is compared to the discharge flow rate. This causes the vehicle speed to become unstable during creep driving. Furthermore, the use of hydraulic power transmission devices, which themselves have low energy efficiency, in mobile work vehicles such as agricultural tractors is
It's not a good idea.

Therefore, this invention has developed a mechanism that allows the vehicle speed to be continuously and stably obtained during creep driving in a traveling work vehicle such as an agricultural tractor that is equipped with a hydraulic clutch type transmission device that changes and controls the vehicle speed in multiple stages. It is a simple structure that uses a hydraulic clutch type transmission and is inexpensive, and is built in so that a vehicle speed range higher than the conventionally adopted creep vehicle speed can be obtained in an efficient manner. It is intended to provide a driving device.

Regarding the illustrated embodiment, the configuration of the traveling drive device for an agricultural tractor or the like according to the invention will be described. In the traveling drive mechanism for the agricultural tractor or the like according to the first embodiment shown in FIG. 1, 1 is an engine; Reference numeral 2 denotes left and right rear wheels which are the final drive means, and the transmission mechanism between the engine 1 and the rear wheels 2 includes a drive shaft 4 which is interlockingly connected to the engine 1 via a main clutch 3 and a drive shaft parallel to the drive shaft 4. A hydraulic clutch type transmission device 6 for changing the traveling power is provided between the transmission shaft 5 and the transmission shaft 5 provided in the vehicle. At the output end of the transmission shaft 5,
A small diameter output bevel gear 7 is provided, and this output bevel gear 7 meshes with a large diameter input bevel gear 9 of a differential device 8 for the left and right rear wheels 2. The differential device 8 is equipped with a differential lock device 10 for selectively inactivating the differential device 8, and the left and right output shafts 11 of the differential device 8 have small diameter gears 12 fitted therein connected to the rear wheel axle. It is interlocked and connected to the left and right rear wheel axles 2a via left and right final gear reduction devices configured to mesh with large-diameter gears 13 fitted to the left and right rear wheel axles 2a.

The hydraulic clutch _type transmission 6, as shown in FIG _{. F1} transmission gear 1 formed by meshing with each other
4 and 15 rows, the _F2 fixed speed change gear 16 fixed to the drive shaft 4, and the F2 fixed transmission gear 16 provided loosely to the transmission shaft _5.
The _F2 speed change gears 16 and 17 rows are formed by meshing the idle speed change gears 17 with each other, and the R fixed speed change gear 18 fixedly provided on the drive shaft 4 are connected to the R intermediate gear 19 supported so as to be freely rotatable. In addition to the rows of R speed change gears 18, 19, and 20 formed by meshing with the R intermediate gear 19 and the R idle speed change gear 20 loosely fitted to the transmission shaft 5, in particular, the R intermediate gear 19 is fixed to the drive shaft 4. A C speed change gear 21 formed by meshing a C fixed speed change gear 21 provided with a C fixed speed change gear 21 and a C idle speed change gear 22 loosely fitted onto a transmission shaft 5,
It is constructed with 22 columns. An F ₁ hydraulic clutch 23 , an F ₂ hydraulic clutch 24 , an R hydraulic clutch 25 , and a C hydraulic clutch 26 are arranged on the transmission shaft 5 for each of the above-mentioned idle speed change gears 15 , 17 , 20 , 22 . . Each hydraulic clutch 23, 2
4, 25, and 26 are configured as well-known multi-disc hydraulic clutches.

The hydraulic clutch type transmission 6 shown in FIG.
By engaging the F ₁ hydraulic clutch 23, the F ₁ idle speed change gear 15 is connected to the transmission shaft 5, and the F ₁ speed change gear 1 is connected to the transmission shaft 5.
By interlocking and connecting the drive shaft 4 and the transmission shaft 5 through the 4th and 15th rows, the gear ratio of the forward _1st speed F1 is set, and by engaging the _F2 hydraulic clutch 24, the _F2 idle speed change gear 17 is set.
is connected to the transmission shaft 5, and the drive shaft 4 and the transmission shaft 5 are interlocked and connected via the F ₂ transmission gears 16 and 17 to control the gear ratio of the forward 2 speed F _2. Furthermore, the R hydraulic clutch 25
By inserting the R idle speed change gear 20, the transmission shaft 5
The drive shaft 4 and the transmission shaft 5 are coupled to each other through the rows of R speed change gears 18, 19, and 20 to provide reverse 1st speed R.
Although the hydraulic clutch type transmission 6 is configured to be able to selectively obtain the respective gear ratios, the hydraulic clutch type transmission 6 also specifically operates the C hydraulic clutch 26 in a slip operation, and the slip operation state of the C hydraulic clutch 26 is The drive shaft 4 and the transmission shaft 5 are interlocked and connected via the C transmission gears 21 and 22 at a reduction ratio greater than the reduction ratio determined by the gear ratios 21 and 22, and the transmission ratio for creep traveling C is determined. It's made up of what you can get.

The construction of the hydraulic circuit for the above purpose will be explained with reference to FIG. 27, hydraulic oil is supplied to the hydraulic clutches 23, 24, 25, and 26 via an oil supply circuit 29. The end of the oil supply circuit 29 is connected to a first electromagnetic switching valve 30 with 5 ports and 3 positions as shown in the figure.
It is connected to the pump port on the primary side, and a lubricating circuit is connected to the downstream side of the first electromagnetic switching valve 30 to connect one port on the secondary side of the first electromagnetic switching valve 30 to the pump port on the primary side. A second electromagnetic switching valve 31 with 4 ports and 3 positions as shown in the figure is provided, which is connected by 29A. One port at each location on the primary side of each electromagnetic switching valve 30, 31 is a tank port, and is connected to the oil tank 28. The other two ports on the secondary side of the first electromagnetic switching valve 30 are connected to the _F1 hydraulic clutch 23 via hydraulic supply/discharge circuits 32 and 33.
and _F2 hydraulic clutch 24, respectively. Two ports on the secondary side of the second electromagnetic switching valve 31 are connected to an R hydraulic clutch 25 and a C hydraulic clutch 26 via hydraulic supply/discharge circuits 34 and 35, respectively. The first electromagnetic switching valve 30 is
The oil supply circuit 29 is connected to the oil supply circuit 29A and the second
A neutral position N where hydraulic oil is supplied to the electromagnetic switching valve 31 direction, and the hydraulic supply/discharge circuits 32 and 33 are connected to the oil tank 28 to disengage the _F1 hydraulic clutch 23 and the _F2 hydraulic clutch 24, and the oil supply circuit. 29 to the hydraulic supply/discharge circuit 32 and connect the _F1 hydraulic clutch 23.
At the same time, the hydraulic supply and discharge circuit 33 is connected to the oil tank 2.
8 to disconnect the _F2 hydraulic clutch 24 and block the oil supply circuit 29A end, and connect the oil supply circuit ₂₉ to the hydraulic supply/discharge circuit 33 to disengage the _F2 hydraulic clutch 24. At the same time,
Connect the hydraulic supply/drain circuit 32 to the oil tank 28
F ₁ Disengage hydraulic clutch 23 and oil supply circuit 2
It is provided with a forward second speed position _F2 that blocks the 9A end. On the other hand, the second electromagnetic switching valve 31 has a neutral position N' where the oil supply circuit 29A and the hydraulic supply/discharge circuits 34 and 35 are connected to the oil tank 28 and disconnects the R hydraulic clutch 25 and the C hydraulic clutch 26, and At the neutral position N of the electromagnetic switching valve 30 of No. 1, the oil supply circuit 2
9A is connected to the hydraulic supply/discharge circuit 34 to engage the R hydraulic clutch 25, and at the same time, the hydraulic supply/discharge circuit 35 is connected to the oil tank 28 and the C hydraulic clutch 26 is disengaged. At the neutral position N of the electromagnetic switching valve 30, the oil supply circuit 29A is connected to the hydraulic supply/discharge circuit 35 to supply hydraulic oil to the C hydraulic clutch 26, and the hydraulic supply/discharge circuit 34 is connected to the oil tank 28. A creep position C for disengaging the R hydraulic clutch 25 is provided. The first electromagnetic switching valve 30 is selectively displaced to each operating position F ₁ , F ₂ by selective excitation of each solenoid 30a, 30b, and the second electromagnetic switching valve 31 is
By selectively energizing each of the solenoids 31a and 31b, the solenoids 31a and 31b are selectively displaced to the respective operating positions R and C. The above solenoids 30a, 30b, 31
One of the terminals a and 31b is selectively energized in order to change the gear position of the hydraulic clutch type transmission 6.

When the first electromagnetic switching valve 30 is placed in the operating position F ₁ , F ₂ and the second electromagnetic switching valve 31 is placed in the operating position R.
When the hydraulic clutches 23, 24, 25
In order to set the hydraulic pressure applied to the first
As shown in the figure, the high pressure regulating valve 37 is inserted into the relief circuit 36 branched from the oil supply circuit 29.
is provided. In the case shown in the figure, the high pressure regulating valve 37 has its pressure setting spring 37a received by a piston 37b that can move forward to a regulated position, and the hydraulic pressure on the primary side of the pressure regulating valve 37 is applied behind the piston 37b through a throttle 38. and move the first electromagnetic switching valve 30 from the neutral position N to each operating position F ₁ , F ₂
and when the second electromagnetic switching valve 31 is switched from the neutral position N' to the working position R, the piston 37b gradually moves forward and the hydraulic pressure gradually rises to the normal hydraulic pressure. , designed to prevent shock when the clutch is inserted. 39 is
This check valve is connected in parallel with the throttle 38 and is used to quickly drain oil from behind the piston 37b when the electromagnetic switching valves 30, 31 are returned to the neutral positions N, N'. The relief oil from the high pressure regulating valve 37 is guided to lubricated parts L such as the friction element parts of the hydraulic clutches 23, 24, 25, 26.

On the other hand, in order to set the hydraulic pressure applied to the C hydraulic clutch 26 when the second electromagnetic switching valve 31 is placed in the creep position C, a relief circuit 40 is branched from the hydraulic pressure supply/discharge circuit 35.
A low pressure regulating valve 41 is provided by being inserted into.
This low pressure regulating valve 41 is designed to set a hydraulic pressure lower than the hydraulic pressure that causes the C hydraulic clutch 26 to fully engage, thereby causing the C hydraulic clutch 26 to operate in slip mode. The low pressure regulating valve 41 shown in FIG. 1 has a pressure setting spring 41a.
The end is received by the movable spring receiver 41b, and the adjustment lever 4
2, the screw rod 43 that is adjusted forward and backward is connected to the movable spring holder 4.
1b, it is possible to change and adjust the set hydraulic pressure by operating a lever 42, and thereby, the hydraulic pressure that is continuously changed and adjusted is applied to the C hydraulic clutch 26, and the C hydraulic clutch 2 is operated in a slip manner.
The engagement degree or slip degree of 6 can be changed and controlled steplessly.

The traveling drive device according to the first embodiment shown in _FIG . When the vehicle is driven normally with the second electromagnetic switching valve 31 in the reverse speed position _F2 or the reverse first speed position R, the hydraulic clutches 23, 24, 25 are engaged corresponding to each switching valve 31 position. but,
The oil pressure set by the high pressure regulating valve 37 is applied to fully engage the gears 14 and 15.
ratio or gear 16, 17 ratio or gear 18, 19, 2
Even at the speed ratio determined by the 0 ratio, the drive shaft 4 and the transmission shaft 5 are interlocked and connected. In contrast,
When the second electromagnetic switching valve 31 is placed in the creep position C, the low oil pressure set by the low pressure relief valve 41 acts on the C hydraulic clutch 26, and the C hydraulic clutch 26 is operated in slip mode.
The drive shaft 4 and the transmission shaft 5 are interlocked and connected at a reduction ratio greater than the reduction ratio determined by the ratio of the gears 21 and 22, allowing the transmission shaft 5 to rotate at an extremely low speed, thereby preventing the vehicle from creeping. I am forced to do it. and,
The vehicle speed during creep traveling can be controlled to be changed steplessly by changing and adjusting the set oil pressure of the low pressure regulating valve 41 steplessly using the adjustment lever 42 as described above.

Next, the second embodiment shown in FIG. 2 will be explained. In this second embodiment, the transmission gear 1 for the first forward speed _F1 in the first embodiment is
The 4th and 15th rows and the hydraulic clutch 23 are also used for the creep speed. That is,
The transmission gears 21 and 22 and the C hydraulic clutch 26 in the first embodiment are the same as the second gear train shown in FIG.
This is omitted in the embodiment, and the _F1 hydraulic clutch 23 has the following configuration. That is, F ₁ hydraulic clutch 23, F ₂ hydraulic clutch 2
Each of the 4 and R hydraulic clutches 25 includes a clutch housing 45 fixed to the transmission shaft 5 and gears 15, 17, 20 extending into the clutch housing 45, as shown in FIG. This is a well-known multi-plate hydraulic clutch in which a plurality of friction plates 46 and mating plates 47 are arranged alternately on each boss extension and supported so as to be slidable only along the clutch axis direction. ing. Each hydraulic clutch 2
A piston 48 is fitted oil-tightly into the clutch housing 45 of No. 3, 24, 25, and hydraulic pressure is selectively applied behind the piston 48, which is biased to move in the backward direction by a return spring 49. As a result, the piston 48 moves forward, and the friction plate 46
It is also well known that the hydraulic clutches 23, 24, 25 are configured to provide press-fit engagement between the mating plate 47 and the mating plate 47.

As described above, in particular, as also shown in _FIG .
8 and a friction plate 4 on the inner diameter side end.
6 and the mating plate 47; an extension portion 48 extending in the opposite direction;
a, and the extension 48a is fitted in an annular slot 45a of a corresponding shape in the clutch housing 45 in an oil-tight manner. and F ₁ hydraulic clutch 2
In the clutch housing 45 of No. 3, there is a first oil chamber 5 located radially outward and behind the piston 48.
0 and the piston extension 48 on the radially inward side.
When hydraulic pressure is introduced into the first oil chamber 50, the width _S1 in the radial direction is changed from the outer diameter end of the extension portion 48a. When hydraulic pressure is applied to the back surface of the piston 48 in the first hydraulic pressure acting part, which has a large area extending up to the outer diameter end of the piston 48, and conversely, when hydraulic pressure is introduced into the second oil chamber 51, the width S in the radial direction Hydraulic pressure is applied to the back surface of the piston 48 in a _second hydraulic pressure acting portion having a small area extending from the inner diameter end to the outer diameter end of the piston extension portion 48a.
An O-ring 52 for sealing oil-tightly between the first oil chamber 50 and the second oil chamber 51 is mounted on the outer peripheral surface of the piston extension 48a. Hydraulic pressure is supplied to the rear of the piston 48 of each hydraulic clutch 23, 24, 25, as usual, through separate oil passages (not shown) drilled in the transmission shaft 5 and drilled in each clutch housing 48. Oil passage (F ₂ hydraulic clutch 2
4 and R hydraulic clutch 25 are arranged to be operated via an oil passage 53) shown in _FIG . A first oil passage 54 communicating with the oil chamber 50 and a second oil passage 55 communicating with the second oil chamber 51 are formed separately, and each oil passage 5
4 and 55 are connected to separate oil passages (not shown) bored in the transmission shaft 5.

As described above, in the second embodiment illustrated in _FIG . 50 and a second oil chamber 51 that applies hydraulic pressure to the back surface of the piston 48 with a second hydraulic acting part having a small area, and separate hydraulic oil supply to each of these oil chambers 50 and 51. drainage channel 54,
55 is guided. Then, a hydraulic circuit similar to that in the first embodiment is provided, and a high hydraulic pressure is selectively introduced to the first oil chamber 50 to fully engage the _F1 hydraulic clutch 23 and shift to the first forward speed F1 _. In addition, a low oil pressure is selectively applied to the second oil chamber 51 to cause the _F1 hydraulic clutch 23 to operate in a slip manner so that the vehicle can creep.

As is clear from the above description, the traveling drive device for agricultural tractors, etc. of this invention is applicable to agricultural tractors, etc. equipped with a hydraulic clutch type transmission device that changes and controls the vehicle speed in multiple stages. A pressure regulating valve 41 is provided which is connected to a hydraulic pressure supply/discharge circuit 35 between the switching valves 30, 31 for switching and controlling the gears and the hydraulic clutch 26 or 23 for the lowest gear in the forward direction of the vehicle. , this pressure regulating valve 41 is connected to the hydraulic clutch 26 or 23.
The hydraulic clutch 26 or 23 is configured as a pressure regulating valve that selectively and steplessly reduces the hydraulic pressure applied to the hydraulic clutch 26 or 23 to cause the hydraulic clutch 26 or 23 to operate in slip mode.

In other words, the travel drive device of this invention operates the hydraulic clutch 26 or 2 by the pressure regulating valve 41.
By selectively reducing the working oil pressure for 3 to an appropriate value and causing the hydraulic clutch to slip at a corresponding slip rate, the vehicle is caused to creep. Since the pressure can be reduced steplessly, it can be controlled and changed steplessly. In addition, according to the present invention, in which the clutch operating hydraulic pressure is reduced by the pressure regulating valve 41 and the vehicle creep running is obtained by the slip operation of the hydraulic clutch 26 or 23, oil leakage is actually reduced by reducing the hydraulic pressure during creep running. together with hydraulic clutch 26
In addition, since the clutch operating oil pressure reduced by the pressure regulating valve 41 provided at a position close to 23 can be precisely maintained, the vehicle speed during creep traveling is stabilized. Moreover, since the hydraulic clutch 26 or 23 for the lowest gear in the forward direction of the vehicle is operated in a slip manner to obtain creep travel, the vehicle speed when the hydraulic clutch 26 or 23 is operated without slipping, i.e. The higher speed side of the hydraulic clutch type transmission can be used in the range from vehicle speeds higher than the conventionally adopted creep vehicle speeds to extremely low creep vehicle speeds when the hydraulic clutches 26 or 23 are operated at high slip ratios. By repeating the vehicle speed that can be obtained by repeating the vehicle speed, stepless speed change can be performed without waste.

Moreover, the creep traveling mechanism utilizes a hydraulic clutch type transmission 6, that is, a transmission mechanism including a transmission gear train of the transmission, a hydraulic pump, a switching valve, a pressure regulating valve for setting a steady clutch operating hydraulic pressure, etc. The present traveling drive device has the above-mentioned advantages, since it is configured by simply adding and connecting a pressure regulating valve 41 for pressure reduction to one hydraulic pressure supply/discharge circuit 35 and using the supply mechanism as is. The structure is extremely simple and can be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is a transmission mechanism diagram and hydraulic circuit diagram showing a first embodiment of this invention, and FIG. 2 is a longitudinal sectional side view of the main parts of a second embodiment of this invention. 1...engine, 2...rear wheel, 4...drive shaft,
5...Transmission shaft, 6...Hydraulic clutch type transmission,
14... _F1 fixed speed change gear, 15... _F1 free rotating speed change gear, 16... _F2 fixed speed change gear, 17... _F2 free rotating speed change gear, 18...R fixed speed change gear, 19...
R intermediate gear, 20...R idle speed change gear, 21...
C fixed speed change gear, 22...C free speed change gear, 23
... _F1 hydraulic clutch, 24... _F2 hydraulic clutch, 25...R hydraulic clutch, 26...C hydraulic clutch, 27...hydraulic pump, 29...oil supply circuit, 29A...oil supply circuit, 30, 31 ...Solenoid switching valve, 32, 33, 34, 35...Hydraulic supply/discharge circuit, 36...Relief circuit, 37...High pressure regulating valve, 40...Relief circuit, 41...Low pressure regulating valve, 41a...Pressure Setting spring, 41b...
...Movable spring holder, 42...Adjustment lever, 43...Screw rod, 45...Clutch housing, 45a...Annular slot, 46...Friction plate, 47...Mating plate, 48
...Piston, 48a...Extension part, 50...First
oil chamber, 51... second oil chamber, 54... first oil passage, 55... second oil passage.

Claims (1)

[Scope of utility model registration request] In an agricultural tractor or the like equipped with a hydraulic clutch type transmission that changes and controls the vehicle speed in multiple stages, a switching valve for switching and controlling the gears of the hydraulic clutch type transmission and a gear for the lowest speed in the forward direction of the vehicle. A pressure regulating valve 41 connected to the hydraulic supply/discharge circuit 35 between the hydraulic clutch and the hydraulic clutch is provided.
A traveling drive device characterized in that: is configured as a pressure regulating valve that selectively and steplessly reduces the hydraulic pressure applied to the hydraulic clutch to cause the hydraulic clutch to operate in slip mode.