JPS6140600Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a transmission device for an agricultural tractor, particularly a transmission device for an agricultural tractor equipped with a hydraulic clutch type transmission device.

Although inventions related to hydraulic clutch type transmissions have already been disclosed, the present invention is particularly applicable to a hydraulic control valve drain in a hydraulic clutch type transmission device in which a hydraulic control valve and a pressure regulating valve are built in a center plate held between a clutch housing and a transmission case. This is an idea related to circuits.

In the case of a hydraulic clutch type transmission, there is a hydraulic clutch device for each gear stage, and these are selectively lubricated with hydraulic pressure from a pump to engage the loose gear and shaft to change gears. The hydraulic pressure of the gears is not released from the hydraulic clutch device,
If the hydraulic clutch of the next gear is engaged, a double mesh phenomenon will occur, leading to destruction of the transmission.

In order to prevent this, it is necessary to completely open the cylinder of the hydraulic clutch to which pressure oil is not supplied to the drain circuit, so that no residual pressure remains, and to create a free state. A gap is formed between the fork shaft integrated with the spool and the spool hole, and the fork shaft is made to escape by using the gap.

The purpose of the present invention is as described above, and the structure of the present invention will be explained based on the accompanying drawings showing embodiments.

FIG. 1 is an overall side view of the agricultural tractor of the present invention.

An engine 7 is disposed within a bonnet 65, and a front wheel 18 is mounted on a front frame from which the engine 7 projects. A clutch housing 2 is attached to the rear surface of the engine 7, and a center plate 1, which is the essential part of the present invention, is sandwiched between the clutch housing 2 and a transmission case 17. A rear axle case 91 is attached to the rear part of the transmission case 17, and the rear axle case 91 is connected to the rear wheel 19.
to support. Further, a hydraulic case 64 for lifting and lowering the working machine is installed on the upper surface of the rear axle case 91.

Reference numeral 8 indicates a shift lever for the auxiliary shift, and reference numeral 6 indicates a main shift lever for the hydraulic clutch type main transmission.

FIG. 2 is a hydraulic system diagram for operating the hydraulic clutch type transmission of the present invention.

Fixed gears 13, 14, 15, 16 on the main shaft 60
are fixedly installed, 13 is for reverse, 14 is for forward 1st speed, 1
5 is a fixed gear for the second forward speed, and 16 is a fixed gear for the third forward speed. Each fixed gear is connected to a hydraulic clutch shaft 61
It meshes with the upper loose fit gears 9a, 10a, 11a, and 12a. However, regarding the fixed gear 13 for reverse movement, the loose fit gear 9a is rotated in the reverse rotation direction via the reverse gear 73 on the reverse gear shaft 117. A
B is a hydraulic control valve which is the essential part of the present invention, and B is a pressure regulating valve to alleviate the shock at the time of starting.

Hydraulic pump 3 is driven by engine 7.

FIG. 3 is a front view of the center plate 1, and FIG. 4 is a rear view of the center plate 1.

The front surface of the center plate 1 faces the clutch housing 2 which is not lubricated by an oil bath, and the rear surface of the center plate 1 forms the front wall of a transmission case 17 which also serves as a hydraulic oil tank. The used hydraulic oil and the drain oil leaking from the pressure regulating valve etc. all flow into the transmission case 17, which is this tank.

A hydraulic pump 3 and a rotation prevention device C are attached to the front surface of the center plate 1. Further, spool holes 70 and 71 are opened within the thickness of the center plate, and a pressure regulating device is fitted into the spool hole 70 and fixed with bolts 69 and 92 to constitute a pressure regulating valve B. The valve spool 20 is fitted into one of the spool holes 71, and the hydraulic control valve A
It consists of

A bearing fitting hole 62 is provided on the rear surface of the center plate 1.
4 pieces a, 60a, 117a, 61a are opened,
From top to bottom: countershaft 62, main shaft 60, reverse gear shaft 117, and hydraulic clutch shaft 61.
is supported by bearings.

Further, a check valve 75 of the drain oil circuit opens to the rear of the pressure regulating valve B near the hydraulic clutch.

FIG. 5 is a sectional view taken along line DD of the center plate 1 in FIG. 3, and FIG. 6 is a sectional view taken along line E-E in FIG. 3.
7 is a sectional view taken along line GG in FIG. 3, and FIG. 8 is a sectional view taken along line FF in FIG. 3.

The flow of hydraulic oil will be explained according to the drawings from Fig. 3 to Fig. 7.

Hydraulic oil is sucked from the oil filter soaked in the oil bath at the bottom of the transmission case.
The oil is sucked into the oil passage 55 by the pipe 56 shown in FIG. The oil filter and pipe 56 are also used for hydraulic oil used in the hydraulic system for lifting and lowering the work machine, and most of the sucked hydraulic oil is sent from the pipe 57 to the hydraulic pump of the hydraulic system for lifting and lowering the work machine. be guided. The hydraulic oil sucked from the oil passage 55 reaches the suction port 54 of the hydraulic pump 3, and from there is sucked into the gear pump consisting of pump gears 4 and 5.
It comes out from the discharge port 53 under pressure. The oil passage 33 runs diagonally through the center plate from the discharge port 53.
is provided and exits to an outlet 34 on the rear surface. A pressure oil port 23 is opened at a right angle in the middle of the oil passage 33, and this pressure oil port 23 directly opens into the spool hole 71 of the hydraulic control valve as a pressure oil port.

On the other hand, the pressurized oil discharged from the outlet 34 on the rear surface passes through the joint oil passage 49 constructed between the center plate 1 and the wall surface of the transmission case, and then passes through the penetrating oil passage 35.
From there, it exits to the joint oil passage 46 on the front. Combined oil path 4
The oil enters the pressure regulating valve B through oil passages 36 and 37 opened at 6. When entering one end of the pressure regulating valve B from the oil passage 36, there is a throttle 90 through which a small amount of pressure oil is introduced to balance it with the large amount of pressure oil that enters from the oil passage 37. When the spool 94 inside the pressure regulating valve B moves upward, the drain port 39 and the pressure oil passage 37 communicate with each other, and a relief action is performed to release the pressure oil to the drain. The bullet 95 in the spool 96 is pushed by the pressure oil flowing through the throttle 90 on the back side of the spool 96 and gradually contracts as the pressure of the pressure oil increases, working to increase the relief pressure. Therefore, conversely, if the hydraulic control valve is in the neutral position and the pressure oil is released through the drain, the relief pressure will be low, and from there
Initially, when the vehicle is put into gear, the pressure acting on the hydraulic clutch is low, and the clutch plate easily slides into a half-clutch state, which prevents a sudden start and provides a smooth start.

When increasing the gear stage from 1st forward speed to 2nd forward speed and then to 3rd forward speed, pressure oil gradually enters from the throttle 90, moves the spool 96 downward, and
By contracting 5, the relief pressure is adjusted in the direction of increasing, and the clutch plate of the hydraulic clutch device no longer slides. When going into reverse, the spool 20 of the hydraulic control valve A passes through the neutral position again, causing the spool 96 of the pressure regulating valve to move upward, and the hydraulic clutch engages with the relief pressure becoming low. This makes it possible to always eliminate the sudden start condition.

Further, the pressure oil is communicated from the pressure regulating valve B, which is an extension of the oil passage 37, to the entrainment prevention device C.

In FIG. 5, the pressure oil in the oil passage 37 enters the cylinder portion 59 into which the piston 97 of the anti-entanglement device is fitted from the oil passage 38 of the anti-entrainment device, pushes the piston 97 to the left, and closes the hydraulic clutch. When in operation, the brake plate 68 is not clamped and the anti-rotation device is not working.

However, when the hydraulic control valve A is in the neutral position, all the pressure oil escapes to the drain, so the pushing force is lost.
The piston 97 is moved to the right by the bullet 66 pushing the back surface thereof, and the brake plate 68 is clamped, thereby preventing rotation of the hydraulic clutch shaft 61.

As a result, when the hydraulic clutch type transmission is in the neutral position, the fixed gears 13, 14, 1 on the main shaft are
When the tractors 5 and 16 are rotating, slight contact between the friction plates causes the tractor to rotate, which prevents the parked tractor from starting on its own.

However, if you attempt to engage the sliding gear for the auxiliary transmission with the main clutch in the disengaged state, the sliding gear may not be able to engage because the main transmission is in a state where it cannot rotate. Therefore, the operating rod 63 is moved to the left by depressing the main clutch pedal 98 to disengage the main clutch, contracting the bullet 66 and opening the ball valve 67. As a result, the hydraulic control valve A is in the neutral state and the cylinder portion 5 is
Even if no pressure oil is supplied to the hydraulic clutch shaft 9, the brake plate 68 can be opened and the hydraulic clutch shaft 61 can be rotated. Drain oil leaked into the chamber of the bomb 66 from the ball valve 67 returns to the tank via the drain oil path 39 and the check valve 75.

Next, referring to the drawings of FIGS. 3 to 14, the speed change operation using the hydraulic control valve A will be described.

FIG. 9 shows the spool 20 of the hydraulic control valve A.
FIG. 10 is a drawing showing a spool device with one forward speed;
FIG. 11 is a drawing showing a spool device with two forward speeds;
Fig. 12 is a drawing showing a spool device with three forward speeds;
Figure 13 is a drawing showing the spool device of the neutral device;
FIG. 14 is a drawing showing the spool device of the reversing device.

Pressure oil flows from the discharge port 53 of the hydraulic pump 3 to the oil path 33
The oil enters the spool hole 71 of the hydraulic control valve from the pressure oil port 23 opened in the middle of the inner thickness of the oil passage 33. It has already been explained that the excess pressure oil reaches the above-mentioned pressure regulating valve through the outlet 34.

In the case of shifting to the first forward speed, in FIG. 10, the oil passes through the small diameter part of the spool 20 from the pressure oil port 23,
It flows into the oil passage 25 of the first forward speed. The oil passage 25 opens on the rear surface of the center plate, enters the lateral oil passage 40 from the mating oil passage 50, passes through the oil passage 53 shown in FIG. 6, and is taken over by the oil passage of the hydraulic clutch shaft. Thereafter, the pressure oil passes through the shaft oil passage of the hydraulic clutch shaft to the hydraulic clutch 10.

In the case of shifting to 2 forward speeds, the spool 20 is moved upward and as shown in FIG. , oil passage 56 in FIG.
The oil is then transferred to the oil passage of the hydraulic clutch shaft 61. Finally, the oil passage in the hydraulic clutch shaft leads to the hydraulic clutch 11.

In the case of the third forward speed, the spool 20 is further pulled upward, and the pressure oil in the pressure oil port 23 flows from the opening 31 in the spool 20 through the through hole 30 to the opening 29 of the spool 20, and the pressure oil flows out into the opening 29 of the spool 20. The oil flows into the oil passage 21 of. The oil passage 21 opens at the rear surface of the center plate 1, and extends from the combined oil passage 48 to the penetrating oil passage 42.
The oil enters the center plate, exits to the front surface of the center plate, passes through the matching oil passage 45, reaches the penetrating oil passage 43, and exits to the rear face of the center plate 1, and reaches the oil passage 44 from the matching oil passage 51.

The oil passage 44 passes through the oil passage 55 shown in FIG.

In the case of the neutral position, pressure oil flows directly from the pressure oil port 23 to the drain port 26, and since the drain port 26 is open on the rear surface of the center plate 1, it returns into the mission case through this opening.

When traveling in reverse, pressurized oil flows from the pressure oil port 23 through the opening 29 of the spool 20, through the through hole 30, to the opening 31, and flows into the oil passage 27 for reversing. The oil passage 27 opens on the front surface of the center plate 1, and runs from the matching oil passage 52 to the oil passage 41, and then to the oil passage 5 in FIG.
4, and finally enters the hydraulic clutch 9 via the oil passage within the shaft of the hydraulic clutch shaft 61.

Next, the drain circuit at the spool position in each speed change state will be explained based on the drawings of FIGS. 10 to 14.

In the first forward speed state, the oil passage 27 for reverse
is in communication with the drain oil passage 29. The drain oil passage 28 is opened at the rear surface of the center plate 1, and returns from there into the tank which also serves as the mission case. The oil passage 24 for the second forward speed exits from the opening 29 of the spool 20 through the through hole 30 to the opening 31,
The drain exits from the rear surface of the center plate 1 through the drain port 26.

The third forward speed oil passage 21 communicates with a drain oil passage 22 .

In the second forward gear shift state, the reverse oil passage 27 communicates with the drain oil passage 28 , and the first forward gear oil passage 25 communicates with the drain oil passage 22 through the inside of the spool 20 . However, at this time, only the third forward speed oil passage 21 does not communicate with the drain port. In the design, oil path 2
It is sufficient to open the drain port on the right side of 1, but since one drain oil passage is provided just for this condition, the spool becomes longer and the precision machining part becomes longer, so it is omitted here. However, oil path 2 of the third forward speed
Since the passage oil passage from 1 to the hydraulic clutch shaft 61 passes through three matching oil passages, the oil passage capacity is large and a double engagement state of the hydraulic clutch does not occur.

The drain circuit in the 3rd forward gear shifting state is as follows:
The reverse oil passage 27 communicates with the drain oil passage 28, the oil passage 25 for the first forward speed communicates with the drain oil passage 26, and the oil passage 24 for the second forward speed communicates with the drain oil passage 22.

In the neutral state, the drain circuit is oil path 2 for reversing.
7 goes to drain oil passage 28, oil passage 25 for 1st forward speed
is connected to the drain oil passage 26, and the oil passage 24 for the second forward speed and the oil passage 21 for the third forward speed are connected to the drain oil passage 22.

In the drain circuit in the reverse state, the oil passage 25 for 1st forward speed is connected to the drain oil passage 26, and the oil passage 24 for 2nd forward speed and the oil path 21 for 3rd forward speed are connected to the drain oil path 22.
The drain oil is communicated with each tank to flow back to the tank, so as not to cause a double engagement condition of the hydraulic clutch.

As shown in the shape of the spool 20 in FIG. 9, in the past, the valve spool and fork shaft were separate bodies, but in the present invention, they are integrated and extend from the tip of the valve spool 20.

A ball 99 fitted into the fork shaft portion 32 of the valve spool 20 from the side surface of the center plate 1 is elastically supported by a spring 100 to prevent movement.

Furthermore, the ball 9 of this forkshaft portion 32
The maximum outer diameter of the fitting part 9 is made smaller than the diameter of the spool hole 41, and the drain oil path 2 is connected from the reverse oil path 27 to the drain oil path 2.
It serves as a passageway to 8. The essential part of the present invention is that a gap is formed between the outer diameter of the fork shaft portion 32 and the inner diameter of the spool hole 71, and the gap is also used as an oil passage for drain oil to the drain oil passage 28. This is the main part of this invention.

FIG. 15 is a side sectional view showing the main shift lever device on the upper part of the center plate, and FIG. 16 is a plan view of FIG. 15.

Gear shift levers are collected on the upper surface of the transmission case 17, and 8 is a sliding gear type sub-shift lever, and 81 is a sliding gear type super low speed gear lever. The main shift lever 6 for operating the hydraulic clutch type transmission is extended via a link 77 to a position on the side of the seat where it can be easily operated.

The link 77 is provided at its tip with an operating link for a bell crank via a shaft 80, and one end of the link 77 is engaged with a long hole in the piston 20a at the upper end of the valve spool 20. Based on the rotation of the main shift lever 6,
The valve spool 20 moves up and down to change gears.

70 is a cover for the gear shift levers 8 and 81;
9 is a speed change guide plate.

As described above, the present invention provides a hydraulic clutch selection leaf pressure oil control valve for a hydraulic clutch type transmission, in which the valve spool 20 is made into a continuous integral structure with the forkshaft portion 32 constituting the detent device, and a single spool hole is provided. 71 into the spool hole 7.
1, the ball 99 for the detent device, which is biased by the spring 100, is projected, and the outer diameter of the fork shaft portion 32 into which the ball 99 fits is made smaller than the outer diameter of the valve spool 20, so that the inner diameter of the spool hole 71 and A gap oil passage is formed between the outer diameter of the forkshaft portion 32 and the gap oil passage is communicated with the drain oil passage 28 that leads into the tank which is also used by the transmission case, so that the following effects are achieved. It is something.

First, the forkshaft portion 32 is continuously integrated with the valve spool 20, the forkshaft portion 32 is configured to have a smaller diameter than the valve spool 20 portion, and this portion is communicated with the drain oil passage 28. The spool hole 71 can be formed by cutting a single hole of the same diameter, and as in the technique described in Japanese Utility Model Application Publication No. 53-143985, the holes in the valve spool 20 part and the fork shaft part 32 part are cut in the middle. This eliminates the need to use this part as a drain circuit.

Second, after being switched by the valve spool 20, the remaining oil in the hydraulic clutch device is completely discharged into the drain oil passage through the drain oil passage which is open and communicated with the gap oil passage between the forkshaft portion 32 and the spool hole 71. This prevents a double meshing condition such as two sets of hydraulic clutch devices joining together.

Thirdly, by passing drain oil through the portion of the forkshaft portion 32 within the spool hole 71 as a drain circuit, the ball 9 provided in the portion is
The parts of the detent device including the spring 9 and the spring 100 can be lubricated, and these parts will not rust.

[Brief explanation of drawings]

Figure 1 is an overall side view of the agricultural tractor of the present invention, Figure 2 is a hydraulic system diagram for operating the hydraulic clutch type transmission, Figure 3 is a front view of the center plate, and Figure 4 is a rear view of the center plate. , FIG. 5 is a sectional view taken along line DD of the center plate in FIG. 3, FIG. 6 is a sectional view taken along line DD in FIG. 3, FIG. 7 is a sectional view taken along line GG in FIG. 3, and FIG. FF sectional view in Figure 3,
Figure 9 is a side view of the spool of the hydraulic control valve;
The figure shows the spool position in forward 1st speed, No. 11.
The figure shows the spool position for forward 2nd speed, 12th
The figure is a drawing showing the spool position of 3rd forward speed, 13th
Figure 14 shows the spool position in the neutral position.
Figure 15 shows the spool position in the reverse position.
This figure is a drawing showing the main shift lever device on the upper part of the center plate, and FIG. 16 is a plan view of FIG. 15. A... Hydraulic control valve, B... Pressure regulating valve, C... Entrainment prevention device, 1... Center plate, 2...
Clutch housing, 3... Hydraulic pump, 6...
Main gear shift lever, 7... Engine, 8... Sub-shift lever, 9, 10, 11, 12... Hydraulic clutch device, 17... Mission case, 20... Valve spool, 28... Drain oil path, 32 ...Forkshaft Department.

Claims (1)

[Scope of utility model registration request] In a hydraulic control valve for selecting a hydraulic clutch in a hydraulic clutch type transmission, the valve spool 20 is made into a continuous integral structure with the forkshaft portion 32 that constitutes the detent device, and is inserted into one spool hole 71. A ball 99 for a detent device, which is biased by a spring 100, is protruded into the fork shaft portion 71, and the outer diameter of the fork shaft portion 32 into which the ball 99 is fitted is made smaller than the outer diameter of the valve spool 20, so that the inner diameter of the spool hole 71 and A gap oil passage is formed between the outer diameter of the forkshaft part 32, and
A transmission device for an agricultural tractor, characterized in that the gap oil passage is communicated with a drain oil passage 28 leading into a tank which also serves as a transmission case.