JPH0439464A - Running speed change structure of work vehicle - Google Patents

Abstract

PURPOSE:To suppress a shock and shorten a speed change operation time as a whole by providing the first control means for off-operating a first clutch by reducing its operating pressure and a second control means for in-operating the clutch by gradually increasing the operating pressure. CONSTITUTION:Since a second clutch 19 is placed in a perfect off-condition by rapidly off-operating the second clutch 19 through speed change operation by actuators T1, T2, T3 to decrease an operating pressure in a first clutch 6 to a predetermined low pressure, a transmission off-condition is obtained as a running system total unit. Accordingly, the speed change operation is performed without a trouble. When the speed change operation is finished, the second clutch 19 is rapidly in-operated, and power transmission is not performed because the first clutch 6 is placed in a not perfect off-condition. Thereafter, a time required before the in-condition is shortened when the first clutch 6 is in-operated by increasing its operating pressure. Since the operating pressure of the first clutch is gradually increased, a shock is reduced when the first clutch 6 is placed in the in-condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a traveling transmission structure for a working vehicle equipped with a gear transmission device for traveling which performs a shifting operation by sliding a shift gear.

[Conventional technology]

Regarding agricultural tractors, which are an example of working vehicles equipped with the above-mentioned gear transmission,
As disclosed in Publication No. 8, some vehicles are equipped with a hydraulic cylinder (corresponding to an actuator) for slidingly operating the shift gear of a gear transmission and a hydraulic clutch for traveling speed change ((C) in the above publication). .

As a result, when a gear shift operation is started using the hydraulic cylinder, the control valve for the hydraulic clutch ((TI) of the above publication,
(T, (T3), (T4)) are automatically operated to the oil drain side, the hydraulic oil for engaging operation is drained from the hydraulic clutch, and this hydraulic clutch is operated to disengage. When the speed change operation by the hydraulic cylinder is completed, the control valve is automatically operated to the hydraulic oil supply side, and the hydraulic clutch is engaged and operated.

As described above, the system is configured such that the gear shift operation can be performed simply by operating the control valve for operating the hydraulic cylinder ((V+) in the above-mentioned publication).

[Problems to be Solved by the Invention] In the above structure, in order to smoothly slide the shift gear using the hydraulic cylinder, it is necessary to completely disengage the hydraulic clutch (that is, completely disable the transmission at any position in the travel transmission system). Therefore, in the above structure, the control valve is operated to the oil drain side at the start of the gear shift operation using the hydraulic cylinder, and the hydraulic oil for engaging and operating the hydraulic clutch is almost completely drained.

Therefore, when the hydraulic oil is supplied to the hydraulic clutch after the end of the speed change operation using the hydraulic cylinder, a certain amount of time is required until the hydraulic oil necessary for the hydraulic clutch to be engaged and operated is supplied. As a result, the entire speed change operation using the hydraulic cylinder and the hydraulic clutch takes a long time.

Therefore, it is conceivable to rapidly supply hydraulic oil to the hydraulic clutch after the shift operation is completed, but this would result in a large shock when the hydraulic clutch is engaged.

An object of the present invention is to shorten the overall time required for a shift operation while suppressing shock in the traveling shift structure for a work vehicle as described above.

[Means for Solving the Problems] The present invention resides in a traveling transmission structure for a work vehicle equipped with an actuator for transmission operation, configured as follows. In other words, the hydraulically operated first clutch presses the friction plate with a piston by supplying hydraulic oil and engages the clutch.
A clutch and a second clutch that can be operated rapidly or with a high degree of latch are provided in series in the travel transmission system, and the second clutch is operated to disengage rapidly in conjunction with the start of a speed change operation by the actuator, and the first clutch is a first control means for reducing the operating pressure of the clutch to a predetermined low pressure and disengaging the first clutch; and rapidly engaging the second clutch in conjunction with the end of the shift operation by the actuator;
and a second control means for gradually increasing the operating pressure of the first clutch to perform a clutch engagement operation,
Its action and effects are as follows.

[For production]

If configured as described above, for example, as shown in FIG. The operating pressure for engaging operation in the first clutch (6) is released to a predetermined low pressure.In this case, the first clutch (6) is not completely disengaged, but the second clutch (6) is not completely disengaged.
Since the clutch (19) is completely disengaged, the entire traveling system is in a transmission disengaged state. Therefore, the speed change operation by the actuators (TI), (T2), and (T3) can be performed without any problem.

And the actuators (T,), ('rz),
(T3) is completed, the second clutch (1
9) is rapidly engaged and operated, but since the first clutch (6) is still not completely disengaged as described above, no power is transmitted. After that, the working pressure of the first clutch (6) is increased to engage and operate the first clutch (6), but in this case, the working pressure is increased from a state where some working pressure remains. Compared to the conventional structure in which the operating pressure is increased from zero, the time required for the first clutch to fully engage is shorter.

When the operating pressure of the first clutch is increased, in the present invention, it is increased gradually, so that the shock when the first clutch enters the engaged state is not particularly large.

[Effects of the Invention] As described above, in the type in which the gear shift operation is performed using an actuator, it is possible to reduce the overall time for the gear shift operation while suppressing shock, and to improve the gear shift performance of the work vehicle. Ta.

〔Example〕

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

As shown in Figure 6, the power from the engine (1) is
Transmission shaft (2), clutch mechanism (3), second transmission shaft (4)
The power from the engine (1) is transmitted to the PTO shaft (5) via the PTO shaft (5) to form the PTO system, and the power from the engine (1) is transmitted to the hydraulically operated first clutch (6), the main transmission (A) (the gear transmission equivalent), second clutch (19), forward/reverse switching device (C
), the rear wheel differential system of the rear wheels (7) via the first auxiliary transmission (B) (corresponding to a gear transmission) and the second auxiliary transmission (D)?
i! (7a) constitutes a traveling transmission system for transmission, and each device is housed in a transmission case (8).

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 hydraulic clutch type front wheel transmission (E), the second intermediate shaft (12), and the front wheels. Def=W! (10a) so that the signal is transmitted to the front wheels (10).

The main transmission (A) is configured as a synchromesh type that slides two sets of shift gears (S), and is capable of shifting into four gears, and includes a forward/reverse switching device (C) and a first sub-transmission ( B) is also configured as a synchromesh type in which the shift gears (sz) and (S3) are slid. Hydraulic cylinders are provided as actuators (r+) and (rz) for slidingly operating both shift gears (S+) of the main transmission (A), and also for sliding the shift gear (S2) of the first sub-transmission (B). A hydraulic cylinder is provided as an actuator (T,) to be operated.

When performing a gear shift operation using each hydraulic cylinder (T,), (Tz), (T3), the first and second clutches (6), (19) are disengaged in conjunction with the start of the shift operation, and the gear shift operation A hydraulic control system is provided that engages and operates the first and second clutches (6) and (19) in conjunction with the termination, and is configured to perform gear shifting operations using hydraulic pressure. Further, the forward/reverse switching device (C) and the second sub-transmission device (D) are manually operated.

Next, the hydraulic control system will be explained. As shown in FIG. 1, the hydraulic oil from the hydraulic pump (13) is supplied to the three sets of hydraulic cylinders (T, ) through the rotary valve (15).
(TZ), (T3) and these three sets of hydraulic cylinders (TI), ('h), (Tel)
A pilot oil passage (16) whose pressure increases and decreases during operation of the forward and backward switching device (C) is provided, and hydraulic oil from the hydraulic pump (13) flows into the first oil passage (17). ) to the rotary valve (15), and via the second oil passage (18) to the first and second clutches (6).

(19).

Furthermore, a hydraulic cylinder (TI) for the main transmission (A),
(TZ) and the forward/reverse lever (28) for the forward/reverse switching device (C), control valves (20), (21), (22) for controlling the pressure in the pilot oil passage (16) are provided. ing.

FIG. 1 shows a case where the main transmission (A), the forward/reverse switching device (C), and the first sub-transmission (B) are in a neutral state, and each control valve (20), (21), (22) is the oil drain position.

However, during normal driving, pilot hydraulic oil from one of the hydraulic cylinders (it) and (Tz) of the main transmission (A) flows from the pilot oil passage (23) or (24) to the control valve (
21) or (22), and the control valve (21) or (22) is operated to the communicating position. Then, the control valve (20) of the forward/reverse lever (28) is in the forward or reverse communication position, and the pilot hydraulic oil from the hydraulic cylinder (T3) of the first sub-transmission (B) is supplied to the pilot oil path ( 2
5), control valves (20), (21), (22),
The second clutch (19) is connected via the pilot oil passage (16).
) is supplied to the operating valve (26) for

As a result, the operation valve (26) is operated to the communication position, and the hydraulic oil from the second oil passage (18) is applied to the second clutch (1
9) is in the engaged state, and the first clutch (6) is also in the engaged state by the hydraulic oil from the second oil passage (18) and the electromagnetic proportional pressure valve (27).

As shown in FIG. 3, the first clutch (6) includes a casing (29) fixed to the first transmission shaft (2), a main transmission 1
If (A) presses the ring member (3I) fixed to the cylindrical shaft (30), the friction plate (32) provided between the casing (29) and the ring member (31), and the friction plate (32). piston (33), the piston (33) is connected to the friction plate (3
2) is configured with a spring (34) that biases it in a direction away from. Then, hydraulic oil is supplied to the piston (33) and the piston (33) is operated to slide.
By pressing 2), the first clutch (6) is engaged, and when the hydraulic oil is removed and the piston (33) is separated from the friction plate (32), the first clutch (6) is disengaged.

With the above configuration, during normal driving as described above (the control valve (21) or (22) and the control valve (20) are in the communicating position, the pilot hydraulic oil from the hydraulic cylinder (T3) is supplied to the operation valve (26). ) and the operation valve (26) is operated to the communication position), the gear shift lever (14)
Assume that the rotary valve (15) is operated at.

In this case, when any of the hydraulic cylinders (TI), (Tz), (TI) starts to operate due to the hydraulic oil from the rotary valve (15), the control valve (21) or (22) is operated to the oil drain position. Otherwise, the pilot oil passage (25) is drained by the hydraulic cylinder (T3). As a result, the pressure in the pilot oil passage (16) decreases, the operation valve (26) is operated to the oil drain position, and the second clutch (19) is rapidly disengaged (time (AI) in Fig. 2). .

When the pressure drop in the pilot oil passage (16) is detected by the pressure sensor (35), the control device (36)
) operates the electromagnetic proportional pressure valve (27), and the operating pressure of the first clutch (6) is reduced from the pressure (p+) corresponding to the fully engaged state to the pressure (P2). This pressure (
P2) is the piston (
33) is a value that is far enough away from the friction plate (32) to touch or not touch the friction plate (32).

Then, between the time 80 and time (A2) shown in FIG. 2, the sliding operations of the shift gears (s+) and (5) by the hydraulic cylinders (TI), (TZ), and (rs) are completed.

At this point (A2), the hydraulic cylinder (T1) or (
Either the control valve (21) or (22) that was in the oil drain position is returned to the communicating position by the pilot hydraulic oil from the hydraulic cylinder (T2), or the pilot hydraulic oil is transferred from the hydraulic cylinder (T3) to the pilot oil path (25). , (16). As a result, the operating valve (26) is operated to the communicating position at time (A2), and the second clutch (19) is rapidly engaged and operated.

When the pressure sensor (35) detects a pressure increase in the pilot oil passage (16) at time point (A2), the control device (36) and the electromagnetic proportional pressure valve (27) increase the operating pressure of the first clutch (6). , from time point (A2) to time point (A3)
It is gradually raised over the period of 20 minutes. As a result, the piston (33), which is in a state of touching or not touching the friction plate (32) shown in FIG. 3, gradually pushes the friction plate (32), and at time (A3), the first clutch ( 6) reaches a pressure (Pl) at which it is completely turned on.

Next, a description will be given of the second clutch (19), which allows rapid important operations. As shown in Figures 4 and 5, the main transmission bag? I Attach the flange (38) to the cylindrical shaft (37) on the (A) side.
) is attached with a spline structure, and a cylindrical casing (39) is connected and fixed to this flange (38). And the forward/reverse switching device (C)! ! The cylindrical shaft (40) of l has a conical surface (41AS) on the outer periphery,
A pair of first and second inner rings (41A) and (41B) formed on the conical surface (41BS)
S) and (41BS) are attached in a spline structure with the two facing in the same direction.

On the other hand, on the casing (39) side, there are a pair of first holes whose inner peripheries are formed into conical surfaces (42AS) and (42BS).
and second outer rings (42A) and (42B) are installed inside. In this case, the inner surface of the casing (39) and the first and second outer rings (42A), (42B)
) grooves (39a), (42Aa), (
42Ba) is formed, and both grooves (39a)
, (42Aa), (42Ba) and the ball (
43) are inserted, and the first and second outer rings (42
A), (42B) rotates integrally with the casing (39), and the first and 27th outer rings (42
A) and (42B) are configured so that they can slide. And the first and second outer rings (424)
.

(42B) (7) Double conical surface (42AS), (42
BS) is the first and second inner ring (41A), (
41B) (7) Double conical surface (41AS).

(41BS), the first and second outer rings (42A) and (42B) are oriented in the same direction.

First and second inner rings (414), (41B)
and the first and second outer rings (42A), (42B
) biconical surfaces (41AS), (41BS), (
Between 42AS) and 42BS, there are Taber-type 1st and 20th lars (42BS) as shown in Figures 4 and 5.
3A) and (43B) are disposed so as to be freely removable around the axes (Y) and (Z) that are inclined with respect to the axis (x). First and second outer rings (42A).

(42B) and the support block (44) fixed to the end of the casing (39) and the second outer ring (42B).
Springs (45) and (46) are respectively installed between the parts B).

A piston (47) is installed inside the casing (39), and by supplying hydraulic oil to the oil passage (48), the piston (47) operates the first and second outer rings (47).
2A) and (42B) can be pressed to the right on the page.

The state shown in FIG.
A) and (42B) are the transmission cut states located on the left side of the page. Then, the piston (47) is moved to the first and second positions by supplying hydraulic oil from the operating valve (26) shown in FIG.
Push the outer rings (42A) and (42B) even slightly to the right in the paper, and then remove the first and second outer rings (42A).
, (42B) is the 1st and 20th-ra (43A)
, (43B), the following state occurs.

In other words, when the cylindrical shaft (37) is rotationally driven in the direction of the arrow (H), the first and 27th outer rings (42A)
, (42B) to the 1st and 20th-ra (43A)
.

(43B), as shown in FIG.
It is rolled slightly in the direction of (K).

As a result, the 10th ring (43A) is connected to the 4th ring of the first outer ring (42A) and the first inner ring (41A).
The left side of the drawing, that is, the conical surface (42AS) of the 17th outer ring (42A) and the first inner ring (41A).

(41AS), and the 10th ring (43A) moves to the side of the narrower space between the 1st inner ring (41A) and the 17th outer ring (42A).
42 AS), and the first inner ring (41
4) and the first outer ring (42A) are integrated, and the power of the cylindrical shaft (37) is transmitted to the cylindrical shaft (40) via the 17th outer ring (42A) and the first inch ring (41A).

On the other hand, in the second inner ring (41B), the 20th
When the -r (43B) rolls in the direction of the arrow (K), the 20th -r (43B) hits the conical surface (42BS) of the second outer ring (42B) and the second inner ring (41B).

(41BS) will be moved to the side with a wider interval.

As a result, the pinching phenomenon of the 20th outer ring (43B) does not occur, and no power is transmitted via the 27th outer ring (42B) and the second inner ring (41B).

Contrary to the above situation, when the cylindrical shaft (37) is rotationally driven in the direction opposite to the arrow (H), the 1st and 20th rollers (438) and (43B) in FIG. Arrow (J)
, it rolls slightly in the opposite direction to (K). This results in
A pinching phenomenon occurs on the 20th outer ring (43B) side, and power is transmitted to the cylindrical shaft (40) via the 27th outer ring (42B) and the second inner ring (41B). On the 10th roller (43A) side, the pinching phenomenon does not occur, and no power is transmitted.

As described above, by providing a pair of one-way clutches with opposite transmission characteristics, it is possible to transmit forward and reverse power.

When even a small amount of hydraulic oil is removed from the piston (47) by the operation valve (26), the spring (45L (46)
) with the urging force of the first and second outer rings (42A).

(42B) is the 1st and 20th-ra (43A), (
43B) to the left in the paper, and the clutch becomes disengaged. As described above, the second clutch (19) can perform important operations rapidly by supplying and discharging hydraulic oil using the operation valve (26).

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[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 the speed change operation system, and FIG. 2 is a time diagram showing the operating pressure and important timing of the first and second clutches. Chart, FIG. 3 is a sectional view of the first clutch, FIG. 4 is a sectional view of the second clutch, and FIG.
FIG. 6, a sectional view taken from the direction (2), is a schematic diagram of the traveling transmission system. (6)...First clutch, (engineering 9)...
・Second clutch, (32)...Friction plate of first clutch, (33)...Piston of first clutch, (A), (B)...Gear Transmission, (S
+), (SZ)...Shift gear of gear transmission, (TO, (rz), (T3)...Actuator.

Claims (1)

[Claims] Actuators (T_1) and (T
_2), (T_3), which is a hydraulically operated gear shift structure for a work vehicle that is equipped with hydraulic oil and presses a friction plate (32) with a piston (33) to engage the clutch. A first clutch (6) and a second clutch (19) capable of rapid clutch on/off operation are provided in series in the travel transmission system, and the actuators (T_1), (T
_2) and (T_3), the second clutch (19) is rapidly disengaged, and the working pressure of the first clutch (6) is reduced to a predetermined low pressure, and the second clutch (19) is rapidly disengaged.
a first control means for disengaging the clutch (6); and a rapid engagement operation for the second clutch (19) in conjunction with the completion of the shift operation by the actuators (T_1), (T_2), and (T_3); A traveling transmission structure for a work vehicle, comprising a second control means for gradually increasing the operating pressure of the first clutch (6) to engage the clutch.