JPH0348062A - Running gear shifting structure for working vehicle - Google Patents

Abstract

PURPOSE:To reduce the generation of a gear shifting shock at an upward and a downward slope and to improve amenity by providing a boosting means to control boosting of the feed working pressure of a working oil feed means for feeding working oil to a hydraulic actuator when a detecting inclination angle exceeds a set value. CONSTITUTION:Since, when gear shifting operation is effected at an upward slope or during traction of a truck or at a muddy ground or when gear shifting operation is performed at a downward slope, the working pressure of a hydraulic actuator for gear shifting operation is increased, the hydraulic actuator effects slide operation of shift gears S1 and S3 of gear shifting devices A and D to gear the shift gears with a transmission gear. As noted above, by performing operation to engage the hydraulic clutch B through slide operation of the shift gears S1 and S3 before a machine body is widely decelerated during gear shifting operation at an upward slope, the occurrence of rapid acceleration phenomenon is suppressed to reduce the generation of gear shifting shock.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a traveling transmission structure for a working vehicle such as an agricultural tractor.

[Conventional technology]

In agricultural tractors, which are one type of work vehicle, for example, as disclosed in Japanese Patent Application Laid-Open No. 64-21254,
Equipped with a hydraulic actuator that slides the shift gear of the gear transmission used for driving,
For example, when the gear shift lever is operated from the 1st gear position to the 2nd gear position, the transmission hydraulic clutch is automatically disengaged, the gear transmission is shifted to the 2nd gear state by the hydraulic actuator, and the hydraulic clutch is engaged again. Some are configured to be manipulated.

As a result, 1), (T2), even if the operator does not press the clutch pedal like in a normal manual type,
This allows you to perform gear shifting operations.

[Problem to be solved by the invention]

In the above-mentioned structure, the operating speed of the hydraulic actuator is set assuming that the vehicle is traveling on a flat surface, and therefore the following problem may occur.

For example, if you perform a gear shift operation when going uphill, towing a trolley, or traveling on muddy ground, a gear shift jerk that causes the aircraft to shake will occur. This is because there is some time after the hydraulic clutch is disengaged until the hydraulic actuator is activated and the shift gear engages with the transmission gear, and during that time the aircraft suddenly decelerates due to running resistance and gravity. At 1) and (T2), when the shift gear engages with the transmission gear and the hydraulic clutch is engaged and operated, a sudden acceleration occurs and a shift shock occurs.

In addition, when downshifting on a downhill slope, the aircraft accelerates rapidly during the above period, so when the shift gear engages with the transmission gear and the hydraulic clutch is engaged and operated,
Engine braking suddenly activates, causing a shift shock.

An object of the present invention is to reduce shift shock during the above-mentioned driving conditions.

[Means to solve the problem]

The present invention is characterized by a hydraulic actuator that slides a shift gear for shifting in a gear transmission device based on an operation command, and a hydraulic actuator that is controlled to be turned off at the start of a gear shifting operation and controlled to be turned on when this shifting operation is completed. A traveling transmission structure for a work vehicle equipped with a hydraulic clutch for transmission is configured as follows. Tsum 1), (T2), ■ A tilt sensor that detects the longitudinal tilt of the aircraft body, and when this detected tilt angle exceeds a set value, increases the supply operating pressure of the hydraulic oil supply means that supplies hydraulic oil to the hydraulic actuator. (1), (T2
), and (1) a load sensor that detects the running load of the aircraft, and a pressure increasing means that increases the supply operating pressure of the hydraulic oil supply means that supplies hydraulic oil to the hydraulic actuator when the detected load exceeds a set value. I am prepared 1)
, (T2), its actions and effects are as follows.

[For production]

With the configuration described above, when a gear shift operation is performed on an uphill slope, when towing a trolley, on a muddy ground, or when a gear shift operation is performed on a downhill slope, the operating pressure of the hydraulic actuator for the gear shift operation is increased. Therefore, the hydraulic actuator quickly slides the shift gear of the gear transmission into engagement with the transmission gear.

As mentioned above, when changing gears on uphill slopes, etc., the aircraft body becomes thicker (by sliding the shift gear and engaging the hydraulic clutch before decelerating (1), (T2),
This suppresses the sudden acceleration phenomenon that occurs with conventional structures and reduces shift shock.

When shifting gears on a downhill slope, by sliding the shift gear and engaging the hydraulic clutch before the aircraft accelerates significantly, 1), (T2), the engine brake is suddenly applied unlike the conventional structure. This makes it possible to reduce the amount of gear shifting and reduce the amount of work required.

[Effects of the Invention] As described above, it was possible to reduce the shift shock when going uphill, downhill, etc., and improve the comfort of the work vehicle.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings using a four-wheel drive agricultural tractor as one of the working vehicles.

As shown in Figure 3, the power from the engine (1) is
Transmission shaft (2), clutch mechanism (3), second transmission shaft (4)
A PTO system is configured in which the power from the engine (1) is transmitted to the PTO shaft (5) via the main clutch (
6), main transmission (A) (corresponds to a gear transmission), hydraulic clutch (B), forward/reverse switching device (C), first auxiliary transmission (D) (corresponds to a gear transmission), second auxiliary transmission Gearbox (E
) A traveling transmission system is configured which transmits the transmission to the rear wheel differential device (7a) of the rear wheels (7) via the rear wheels (7), and each device is housed inside a transmission case (8).

Then, the power branched from just before the rear wheel differential device (7a) is transmitted to the gear transmission mechanism (9), the first intermediate shaft (11), the front wheel transmission (F), the second intermediate shaft (12), and the front wheel differential device ( 1
0a) to the front wheels (10).

The main transmission (A) is configured as a synchromesh type that slides two sets of shift gears (Sl), and is capable of shifting into four stages. The first sub-transmission device (D) also has each shift gear (32).

It is configured as a synchronized mesh type in which (S3) is operated by sliding. A hydraulic actuator (T) slides both shift gears (Sl) of the main transmission (A).
Hydraulic cylinders are provided as I) and (T2), and a hydraulic cylinder as a hydraulic actuator (T3) that slides the shift gear (S,) of the first sub-transmission device (D) is provided.

Furthermore, each hydraulic cylinder (TI), (TI),
(T3), a hydraulic control system is provided which disengages the hydraulic clutch (B) before the shift operation starts, and engages and operates the hydraulic clutch (B) when the shift operation is completed. (T2), the gear shift operation can be performed using hydraulic pressure without disengaging the main clutch (6). In addition, the forward/reverse switching device (C) and the second
The auxiliary transmission (E) is operated manually.

Next, the hydraulic control system will be described in detail. As shown in FIG. 1, the hydraulic oil from the hydraulic pump (13) is supplied to the three sets of hydraulic cylinders (TI) through the rotary valve (15).
(T2), (T3) and these three sets of hydraulic cylinders (TI), (T2), (T3)
A pilot oil passage (16) whose pressure increases and decreases when the is operated and when the forward/reverse switching device (C) is operated, and a valve mechanism (v) that is operated by the pilot pressure of this pilot oil passage (16). A hydraulic control system is constituted by a hydraulic clutch (B) which is controlled by this valve mechanism (v). Hydraulic oil from the hydraulic pump (I3) is supplied to the rotary valve (15) via the first supply oil passage (17) and to the valve mechanism (v) via the second supply oil passage (18). .

The rotary valve (15) is connected to each hydraulic cylinder (TI
), (T2), ('rs), and a pilot pressure control section (15b) that controls the pressure of the pilot oil passage (16). T2), the operator performs a switching operation using the gear shift lever (14).

Furthermore, each hydraulic cylinder (TI), (T2),
(T3) and the forward/reverse lever (28) for the forward/reverse switching device (C), a valve portion (G) for controlling the pressure of the pilot oil passage (16) is provided.

Figure 1 shows the case where the main transmission (A), forward/reverse switching device (C), and first sub-transmission (D) are all in the neutral state.
), (T2), each valve part (G) is in the open position,
During normal driving, one valve part (G) of the hydraulic cylinder (71), (T2) in the main transmission (A) is in the closed position, and the other valve part (G) of the hydraulic cylinder (71), (T2) is in the closed position. At the same time that the valve part (G
) and the hydraulic cylinder (T
, ) are in the closed position.

As a result, 1), (T2), when the rotary valve (15) is operated with the gear shift lever (14), the pilot oil passage (16) is controlled by the pilot pressure control section (15b) at the start of the operation.
At the same time, the pressure in the main transmission (A) hydraulic cylinders (TI), (T
or the hydraulic cylinder (T, ) of the first auxiliary transmission (D) is operated. And this hydraulic cylinder (TI), (
During the operation of T2) and (T3), any valve part (G
) is in the open position, and the pilot oil passage (16) is maintained at low pressure.

This pressure drop in the pilot oil passage (16) causes the on-off valve (
36) becomes the oil draining position, and the hydraulic clutch (B) is disengaged. And hydraulic cylinders (T1), (T2)
, (T2), and (TI) are completed, the valve part (G) that was in the open position becomes the closed position and the pilot oil path (
16) increases, the on-off valve (36) goes to the hydraulic oil supply position 1), (T2), and the hydraulic clutch (B) is engaged and operated.

More specifically, as shown in FIGS. 2 and 1, 3
Set of hydraulic cylinders (TI), (Tz), (Ta
) and a rod member (19) for operating the forward/reverse switching device (C) are housed in a single cylinder case (20) configured in a block shape.

1), (T2), hydraulic cylinder (TI) for the main transmission (A), (Tz) is the piston part (21)
A member having two piston rods (22) and (22) on both sides, a movable piston (23) fitted onto the other piston rod (22), and this movable piston (23).
Side piston rod (22) and cylinder case (20)
It is composed of a sleeve member (24) etc. that is interposed between the inner surface and the inner surface of the sleeve member. This sleeve member (24) is connected to the cylinder case (20) via an oil seal (25) made of an elastic material.
The valve portion (C) is fitted into the inside of the piston rod, and further includes an oil passage (24a) formed in the sleeve member (24) and a concave portion (22a) formed in the piston rod (22).

The sleeve member (24) is fixed in position with respect to the cylinder case (20) by a clip (26). In addition, the piston rod (2) on the side where the engaging portion (27) is provided
An oil seal (
25) is provided.

In these hydraulic cylinders (Tl) and (T2), three sets of hydraulic ports (PI) are provided so as to provide three operating positions.
, (PI), and (P3) are provided. Tsum 1)
, (T2), When hydraulic oil is simultaneously supplied to the hydraulic ports (PI) and (P3) at both ends, the piston portion (2I) and the piston rod (22) stop at the neutral position shown in FIG. Then, when hydraulic oil is supplied to the hydraulic port (PI) on the left side of the page, the piston portion (21) and the piston rod (22) move to the right side of the page together with the movable piston (23), and the movable piston (23) stops at the position where it hits the sleeve member (24). Conversely, the hydraulic port (
When hydraulic oil is supplied to the piston (PI), the movable piston (23) moves to the right in the paper until it hits the sleeve member (24), and then the piston part (21) and piston rod (22)
moves to the left on the page.

The hydraulic cylinders (TI) for the first sub-transmission (D) are the hydraulic cylinders (TI), (T
2) with the movable piston (23) removed.
), (T2), two sets of hydraulic ports (PI), (P,)
It can be operated in two positions by selectively supplying hydraulic oil to the valve. Further, the rod member (19) is arranged to pass through the cylinder case (20), and has a bracket (29) at one end that is linked to the forward/reverse lever (28) and an engaging bracket at the other end. A valve portion (G) is formed between the rod member (19) and the cylinder case (20).
) is formed.

Next, each hydraulic cylinder (TI), (T2), (TI
) operating speed control will be explained in detail. As shown in Figure 1, high pressure +) +) opens at high pressure in the first supply oil path (17).
- open at low pressure (low pressure relief valve (44))
are connected in parallel, and a low pressure relief valve (44)
An electromagnetic on-off valve serving as a pressure increasing means (45) is connected in series on the downstream side of the pump. A weight-type inclination sensor (46) for detecting longitudinal inclination of the aircraft body is provided, and this inclination sensor (46) and an on-off valve (45) are electrically linked.

Due to the above structure, 1), (T2), the on-off valve (45) is in the open position during normal driving on flat ground 1), (T2), and the low pressure relief valve (44) increases the pressure of the entire hydraulic control system. is determined and the hydraulic cylinder ('
r,).

(T2) and (TI) operate. When the slope of the aircraft's front uphill or rear uphill slope exceeds the set value, the on-off valve (4
5) is operated to close. This results in 1), (T2), low pressure I
J IJ-F valve (44) no longer functions 1), (T2)
, the pressure of the entire hydraulic control system is increased to the pressure based on the high pressure relief valve (43). Therefore, if you perform a gear shift operation in this state, this high pressure will cause the hydraulic cylinder (TI) to
TI).

(TI) operates quickly.

Next, the valve mechanism (■
) will be explained in detail. As shown in FIG. 1, the second supply oil passage (18) from the hydraulic pump (13) is connected to the first oil passage (34).
) and the second oil passage (35) in parallel, and the first oil passage (
34) is provided with an electromagnetic proportional pressure reducing type pressure regulating valve (33),
The second oil passage (35) is provided with an on-off valve (36) that is operated by the pilot pressure of the pilot oil passage (16). When the on-off valve (36) is in the hydraulic oil supply position and the pressure of the hydraulic clutch (B) rises to a set value, a pressure reducing valve (37) is provided to close the second oil passage (35). It is being

During normal running, the on-off valve (36) is in the hydraulic oil supply position 1), (T2), and the hydraulic clutch (B) is in the engaged state. Then, as mentioned above, the hydraulic cylinder (T+)
, (T2), (T3) or forward/backward lever (28
), the on-off valve (36) becomes the oil draining position and the hydraulic clutch (B) is disengaged. When the shift operation is completed and the pressure in the pilot oil passage (16) rises, the on-off valve (36) switches to the hydraulic oil supply position 1), (T2), and shortens the pressure in the hydraulic clutch (B). Raise it to a half-clutch state within a certain amount of time.

In such a state, the pressure reducing valve (37) is closed, the pressure switch (40) detects a pressure increase, the pressure regulating valve (33) starts operating, and the hydraulic clutch (B
) pressure is slowly increased. In this case, the pressure regulating valve (33) is operated by the control device (39) so that the detected value of the torque sensor (38) provided in the traveling transmission system is maintained at approximately a predetermined value. T2), 1), (T2), the hydraulic clutch (B) can be smoothly engaged and operated.

Then, as shown in FIG. 3, the cylinder case (20),
The rotary valve (15), valve mechanism m, etc. are combined into one block-shaped hydraulic unit (31).
), an opening (8a) formed in the mission case (8)
) is attached to the hydraulic unit (31) so as to block it. On the other hand, each shift gear (SL) of the main transmission (A), forward/reverse switching device (C), and first sub-transmission (D)
), (S2), (Shift fork that engages with S (
47) and a shift shaft (32) that supports this shift fork (47).

One end of the foot shaft (32) extends to the opening (8a) of the transmission case (8).

The extending end of each shift shaft (32) is connected to a hydraulic unit (
1), (T2), each hydraulic cylinder (T+), (
Each shift gear (St), (s1), (T2), (S
, ) can be operated by sliding.

In addition, the front wheel transmission (F) installed in the mission case (8) includes a gear transmission mechanism (41) and a hydraulic clutch (42).
), etc. 1), (T2), when the front wheel (10) is steered beyond the set angle, the front wheel (10) turns into the rear wheel (
7) The gears are changed so that the vehicle is driven at a higher speed than 7).

[Another example]

As mentioned above, the on-off valve (45
) rather than operating the on-off valve ( 45) may be closed.

The hydraulic pump (13) may be of a variable output type, and the hydraulic pump (13) may be operated to increase the output based on the detected value of the inclination sensor (46) or the torque sensor (38).

Incidentally, although reference numerals are written in the claims section for convenience of reference to the drawings, the present invention is not limited to the structure shown in the accompanying drawings by such entry.

[Brief explanation of drawings]

The drawings show an embodiment of the traveling speed change structure for a work vehicle according to the present invention, FIG. 1 is a hydraulic circuit diagram of each hydraulic cylinder and a valve mechanism, etc., and FIG. 2 is a diagram of a cylinder case equipped with each hydraulic cylinder and a rod member. The sectional view, FIG. 3, is a schematic diagram of the traveling transmission system. (38)...Load sensor, (45)...
- Boosting means, (46)... Tilt sensor, (A)
, (D)...Gear transmission, (B)...
・Hydraulic clutch, (31), (S3)...Shift gear, (71), (T2), ('rs)・
...Hydraulic actuator.

Claims (1)

[Claims] 1. Hydraulic actuators (T_1) and (T_
2), (T_3) and this hydraulic actuator (T_1
), (T_2), and (T_3), the transmission hydraulic clutch (B) is controlled to be disengaged at the start of the shift operation, and is engaged and controlled at the completion of the shift operation. , a tilt sensor (46) that detects the longitudinal tilt of the aircraft, and when the detected tilt angle exceeds a set value, the hydraulic actuators (T_1), (T_2), (T
_3) A traveling transmission structure for a work vehicle, which is equipped with a pressure increasing means (45) for increasing the supply operating pressure of a hydraulic oil supply means for supplying hydraulic oil. 2. Hydraulic actuators (T_1) and (T_
2), (T_3) and this hydraulic actuator (T_1
), (T_2), and (T_3), the transmission hydraulic clutch (B) is controlled to be disengaged at the start of the shift operation, and is engaged and controlled at the completion of the shift operation. , a load sensor (38) that detects the running load of the aircraft, and when this detected load exceeds a set value, the hydraulic actuators (T_1), (T_2), (T_3)
) A traveling transmission structure for a working vehicle, comprising a pressure increasing means (45) for increasing the supply operating pressure of a hydraulic oil supply means for supplying hydraulic oil to a working vehicle.