JP3126894B2 - Work vehicle traveling speed change structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling speed change structure for a working vehicle.

[0002]

2. Description of the Related Art In a working vehicle, for example, as shown in FIG. 1, power from an engine 1 is transmitted to main clutches 5, 6 of a hydraulic multi-plate type, a main transmission 10, and a first auxiliary transmission 11. The main transmission 10 and the first auxiliary transmission 11 are of a hydraulic clutch type that performs a speed change operation by supplying hydraulic oil to one of a plurality of hydraulic clutches and operating the transmission side. There is.

In this case, for example, as shown in FIG. 1, a second sub-transmission 1 of a gear transmission type in which a shift operation is performed by sliding operation of a shift member 53 is provided on a lower side of the first sub-transmission 11.
The second and third auxiliary transmissions 63 may be provided. As a result, the main transmission 10
This supplements the first subtransmission 11 and widens the speed change range of the main transmission 10 and the first subtransmission 11, so that the third subtransmission 63 is operated at a very low speed by the speed change operation.

[0004]

In the configuration shown in FIG. 1, when the second sub-transmission 12 is operated in a state in which the third transmission 63 sets an extremely low-speed running state, the vehicle is generally operated by shifting its body. It is often performed while stopped. In this case, in general, the shift operation of the shift member 53 by the shift lever is performed to shift the second sub-transmission 12 in a state where the main clutches 5 and 6 are operated to the transmission interruption side and the machine body is stopped.

[0005] In this case, if an extremely low-speed running state is set by the third transmission 63, power of low rotation and high torque is flowing. The surface pressure of the bite portion of the shift member 53 of the second auxiliary transmission 12 is high. Even when the main clutches 5 and 6 are operated to the transmission cutoff side, a so-called friction plate rotating phenomenon occurs in the hydraulic multiple disc type main clutches 5 and 6, and the power of the engine 1 causes the main clutches 5 and 6 to operate. The second sub-transmission 12 is transmitted little by little to the lower sub-transmission 12 via the lower side, and the motive force further increases the surface pressure of the bite portion of the shift member 53 of the second sub-transmission 12.

Therefore, when the shift operation is performed by sliding the shift member of the second auxiliary transmission with the shift lever in the above-described state, the sliding operation of first releasing the bite of the shift member by the above-mentioned surface pressure is heavy. It may be. Also, while the lower transmission shaft of the second subtransmission is stopped (due to the stop of the body), the upper transmission shaft of the second subtransmission is rotated by the power transmitted little by little from the engine. It is in a state that it is doing. Due to this, it is not possible to properly engage the shift member with another shift position due to the rotational speed difference between the upper and lower transmission shafts of the second auxiliary transmission, and the shift operation of the second auxiliary transmission by the shift lever. Can be heavy. The present invention relates to a traveling speed change structure of a work vehicle including a hydraulic clutch type main transmission and a first auxiliary transmission, and a gear transmission type second and third auxiliary transmission. It is an object of the present invention to provide a configuration in which when the state is set, the speed change operation of the second auxiliary transmission can be performed lightly.

[0007]

A feature of the present invention resides in the following construction in the traveling speed change structure of a work vehicle as described above. [1] Hydraulic multi-disc main clutch,
Main transmission, first auxiliary transmission, second auxiliary transmission, and third transmission
The transmission is transmitted to the auxiliary transmission in this order and the transmission is operated to transmit the transmission to the traveling device on the lower side.
The auxiliary transmission is a hydraulic clutch type in which a plurality of multi-plate hydraulic clutches are arranged in parallel, and hydraulic oil is supplied to one of the plurality of hydraulic clutches and operated to the transmission side to shift the speed. The second auxiliary transmission and the third auxiliary transmission are configured as a gear shift type in which a shift operation is performed by sliding operation of a shift member, and the shift member of the second auxiliary transmission and the shift lever are mechanically interlocked. The speed change lever is configured to perform a speed change operation of the second sub-transmission, and the discrimination means for determining whether the third sub-transmission is operated to shift to a lower speed side; Third based on
In the state where the subtransmission is being shifted to the low speed side, the second
When a shift operation by the shift lever of the sub-transmission is started, the main clutch and all hydraulic clutches of the first sub-transmission are operated to the transmission cutoff side, and two or more hydraulic clutches in the main transmission are operated. The first control means for operating the first transmission on the transmission side, and one of the predetermined hydraulic clutches in the first auxiliary transmission is operated on the transmission side with the end of the shift operation by the shift lever of the second auxiliary transmission. A second control means for operating the hydraulic clutch operated on the transmission side in the transmission to the transmission cutoff side, operating one predetermined hydraulic clutch on the transmission side, and allowing the main clutch to be operated on the transmission side; Is provided.

[2] In the configuration of the above item [1], a lock mechanism capable of holding and releasing the shift lever of the second auxiliary transmission at each shift position is provided, and the operation of the lock mechanism toward the release release side is performed by the shift lever. When the lock mechanism is operated to the holding release side while the third subtransmission is being shifted to the low speed side, the first control means starts operating. The lock mechanism and the first control means are linked.

[0009]

[Action]

[I] With the configuration as described in [1] above, for example, in the configuration shown in FIG. 1, the second auxiliary transmission 12
When the shift operation by the shift lever is started when the shift operation is performed by sliding the shift member 53, the transmission of the main clutches 5, 6 and all the hydraulic clutches 26, 27 of the first auxiliary transmission 11 are interrupted. (The hydraulic clutch operated on the transmission side in the first subtransmission 11 is operated on the transmission cutoff side, and the hydraulic clutch operated on the transmission cutoff side is held on the transmission cutoff side). At the same time, the plurality of hydraulic clutches 21, 22,
Two or more hydraulic clutches out of 23 and 24 are operated to the transmission side.

In this case, in a state where the main clutches 5, 6 shown in FIG. 1 are operated to the transmission cutoff side, the power of the engine 1 causes the main clutches 5, 6 to move due to the entrainment phenomenon in the main clutches 5, 6. Through the main transmission 10, the two or more hydraulic clutches are operated to the transmission side in the main transmission 10.
Since 0 is a multiple transmission state with different transmission ratios due to two or more hydraulic clutches, and is in a state where braking has been applied,
The power is stopped in the main transmission 10, and the entrainment phenomenon in the main clutches 5, 6 is also stopped. Since all the hydraulic clutches 26 and 27 of the first auxiliary transmission 11 are operated to the transmission cutoff side, the transmission shaft on the lower side (the traveling devices 14 and 19 side) of the second auxiliary transmission 12 is Even if the vehicle is stopped by the stop, the upper side (the first auxiliary transmission 11
The transmission shaft on the side is stopped so that it can rotate freely.

Therefore, even if the third transmission 63 is shifted to the low speed side, even if the surface pressure of the bite portion of the shift member 53 of the second auxiliary transmission 12 becomes high,
Upper side of the second auxiliary transmission 12 (the first auxiliary transmission 11 side)
As a result, the surface pressure at the occlusal portion is released and disappears. Further, since the power from the engine 1 is not transmitted to the shift member 53 of the second subtransmission 12, the power from the engine 1 does not apply surface pressure to the occlusal portion of the shift member 53. Thus, the shift member 53 of the second auxiliary transmission 12 can be slid by the shift lever, and the bite portion of the shift member 53 can be lightly pulled out.

Next, when the shift member 53 is disengaged from the engagement portion, the transmission shaft on the upper side of the second auxiliary transmission 12 (the first auxiliary transmission 11 side) can freely rotate. Even if the phases of the parts do not match, the transmission shaft on the upper side (the side of the first sub-transmission 11) of the second sub-transmission 12 slightly rotates with the sliding operation of the shift member 53, and the phase coincides. In addition, the shift member 53 can be lightly slid to be occluded.

When the shifting operation of the second sub-transmission 12 by the shift lever is completed as described above, one predetermined hydraulic clutch of the first sub-transmission 11 is operated to the transmission side before the shift operation by the shift lever. Original hydraulic clutch)
Is operated on the transmission side, and two or more hydraulic clutches operated on the transmission side in the main transmission 10 are operated on the transmission cutoff side, and a predetermined one hydraulic clutch (the transmission side is operated before the shift operation by the shift lever). The original hydraulic clutch, which had been operated in the above manner, is operated to the transmission side, the operation of the main clutches 5, 6 to the transmission side is permitted, and the main transmission 10 and the first sub transmission 11 are operated by the shift lever. Return to the previous state.

[II] Since the body is running at a relatively high speed when the third sub-transmission 63 is not shifting to the low speed side, the shifting operation of the second sub-transmission 12 in this state is not Often done during. Therefore, when the gearshift operation of the second auxiliary transmission 12 is performed while the body is running, if the operation as described in the preceding item [I] is performed, for example, in the second auxiliary transmission 12 shown in FIG. While the transmission shafts of the traveling devices 14 and 19) are rotated by the traveling of the fuselage, the transmission shaft of the upper side (the first auxiliary transmission 11 side) stops and the upper and lower transmission shafts stop. The difference in the number of rotations of the transmission shaft increases, and it becomes difficult for the phase of the occlusal portion of the shift member 53 of the second transmission 12 to match.

In this case, if the third sub-transmission 63 is not operated to shift to the low speed side in the configuration shown in FIG. When performing the speed change operation of the above [I]
Is not performed. Accordingly, the vehicle is traveling (a state in which the third sub-transmission 63 is not operated to shift to a lower speed).
In the case where the shift operation of the second auxiliary transmission 12 is performed,
As in the case of a normal manual type transmission, the main clutches 5, 6 are artificially operated to the transmission interrupting side (or automatically operated to the transmission interrupting side) by a clutch pedal or the like, and the second clutch is operated.
The shift operation of the auxiliary transmission 12 may be performed. This allows
In the second auxiliary transmission 12, the lower side (the traveling devices 14, 1)
The transmission shaft of the second sub-transmission 12 is slid while the transmission shaft of the second sub-transmission 12 is rotated by inertia while the transmission shaft of the second sub transmission 12 is rotated by the inertia of the transmission shaft of the second sub transmission 12. The operation is performed, and the phase of the occlusal portion of the shift member 53 is easily matched to perform the speed change operation.

[III] When configured as in the above item [2], similar to the case of the above item [1], it has the "action" described in the above items [I] and [II]. It has the following “action”. The shift lever as described in [1] above may include a lock mechanism that can hold and release the shift lever at each shift position.
In the shifting operation by the shift lever, first, the lock mechanism operated on the holding side is operated on the release side, and then the shifting operation by the shift lever is started.

As a result, all the hydraulic clutches 2 of the main clutches 5, 6 and the first subtransmission 11 are linked to the operation of releasing the lock mechanism to the holding release side as in the configuration [2].
6 and 27, the operation of the main transmission 10 to the transmission side of the two or more hydraulic clutches is started, so that the shift member 53 of the second auxiliary transmission 12 by the shift lever is provided. When the slide operation is actually started, the power transmission in the main transmission 10 as described in the preceding section [I] has been sufficiently performed, so that the speed change operation by the speed change lever is light and smooth from the beginning. I can do it.

[0018]

According to the first aspect of the present invention, there is provided a traveling speed change structure of a working vehicle including a main transmission and a first auxiliary transmission of a hydraulic clutch type, and second and third auxiliary transmissions of a gear transmission type. In the case of an ultra-low speed running state in which the third sub-transmission is operated to the low speed side, the main transmission is set to the multiple transmission state to cut off the power of the engine, thereby stopping the body of the second sub-transmission. The speed change operation of the work vehicle can be improved smoothly and smoothly. In this case, two or more hydraulic clutches of the main transmission having the existing configuration may be operated on the transmission side, and a dedicated device for preventing the power of the engine from being transmitted to the second auxiliary transmission is provided. Since there is no need, there is an advantage in terms of simplification of the structure. When the third sub-transmission is not shifted to the low speed side, the multiple transmission state in the main transmission as described above does not appear. Can be done without any trouble.

According to the second aspect of the invention, the above-mentioned "effect of the invention" of the first aspect is provided, similarly to the case of the first aspect. When a lock mechanism for the shift lever is provided, the holding release operation of the lock mechanism performed at the beginning of the shift operation allows the operation of the two or more hydraulic clutches of the main transmission to be transmitted to the transmission side. When the actual shift operation by the shift lever is started, the power is sufficiently shut off by the main transmission, so that the shift operation by the shift lever can be performed lightly and smoothly from the beginning. Was able to further improve the shifting performance.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. (1) FIG. 1 shows the inside of a transmission case 8 of a four-wheel drive type agricultural tractor, which is an example of a work vehicle, and an engine 1
Is transmitted to the PTO shaft 4 via the transmission shaft 2 and the hydraulic multi-plate PTO clutch 3. The power from the engine 1 is supplied to the forward clutch 5 (corresponding to the main clutch) or the reverse clutch 6 (corresponding to the main clutch), the cylindrical shaft 7, the main transmission 10, the first subtransmission 11, and the second subtransmission 1.
The power is transmitted to the left and right rear wheels 14 (corresponding to a traveling device) via the second and third auxiliary transmissions 63 and the rear wheel differential device 13. The power branched immediately before the rear wheel differential device 13 is transmitted to the transmission shaft 1.
5. The power is transmitted to the left and right front wheels 19 (corresponding to a traveling device) via a hydraulic clutch type front wheel transmission 16, a front wheel transmission shaft 17, and a front wheel differential device 18.

The forward clutch 5 and the reverse clutch 6 are of a hydraulic multi-plate type combining a friction plate (not shown) and a piston (not shown), and are operated to the transmission side by supplying hydraulic oil. When the forward clutch 5 is operated to the transmission side,
The power of the engine 1 flows directly from the forward clutch 5 to the cylindrical shaft 7, and the aircraft advances. When the reverse clutch 6 is operated to the transmission side, the power of the engine 1 is transmitted to the cylindrical shaft 7 in a reverse rotation state via the reverse clutch 6 and the transmission shaft 20, and the body moves backward.

The main transmission 10 comprises four hydraulic multi-plate type first speed clutches 21 (corresponding to hydraulic clutches), second speed clutches 2
2 (corresponding to a hydraulic clutch), a 3rd speed clutch 23 (corresponding to a hydraulic clutch), and a 4th speed clutch 24 (corresponding to a hydraulic clutch) are arranged in a hydraulic clutch type, and can be shifted to four speeds. 1st to 4th speed clutch 21 to
By operating one of the transmissions 24 to the transmission side, the power from the cylindrical shaft 7 on the engine 1 side is shifted to four stages and transmitted to the transmission shaft 25 on the lower side.

The first auxiliary transmission 11 is also of a hydraulic clutch type in which two hydraulic multi-plate low-speed clutches 26 (corresponding to a hydraulic clutch) and a high-speed clutch 27 (corresponding to a hydraulic clutch) are arranged in parallel. It can be shifted in two steps,
By operating one of the low-speed and high-speed clutches 26 and 27 to the transmission side, the power from the transmission shaft 25 on the main transmission 10 is shifted to two stages, and the second auxiliary transmission 1 on the lower side is operated.
2 is transmitted. The second auxiliary transmission 12 and the third auxiliary transmission 63 are of a synchromesh type that slides the shift members 53 and 68, and is configured to be able to shift to two speeds.

(2) Next, the forward and reverse clutches 5, 6,
A hydraulic circuit for the main transmission 10 and the like will be described. FIG.
As shown in the figure, an electromagnetic proportional valve 35 for the forward and reverse clutches 5 and 6, the pilot operated switching valves 36a and 37a, and one of the main transmissions 10 are provided in the oil passage 30 from the pump 29.
The pilot operated switching valves 31a, 32a, 33a, 34a for the first to fourth speed clutches 21 to 24, and the electromagnetic proportional valves 38, 39 for the low speed and high speed clutches 26, 27 of the first auxiliary transmission 11, are connected in parallel. ing.

An oil passage 40 branched from the oil passage 30 is provided with a hydraulic clutch 4 for a differential lock operation in the front wheel differential device 18.
1, a pilot-operated switching valve 42a for the rear wheel 1 and a hydraulic clutch 43 for a differential lock operation in the rear wheel differential device 13.
, A pilot operated switching valve 44a, a standard clutch 45 of the front wheel transmission 16, and a speed increasing clutch 46 (FIG. 1).
Pilot operated change-over valves 47a, 48
a are connected in parallel. Each switching valve 31a-34
a, 36a, 37a, 42a, 44a, 47a, 48a
Is urged toward the oil drain side (transmission blocking side) by a spring, and is operated on the supply side (transmission side) by supplying pilot hydraulic oil as described later.

A pilot oil passage 50 branches from the oil passage 30 via a pressure reducing valve 49, and the pilot oil passage 50 is connected to the switching valves 31a to 34a, 36a, 37a, 42a, 44a,
47a, 48a are connected to the operation units, and each operation unit is provided with an electromagnetic operation valve 31b, 32b, 33b, 34b, 36b,
37b, 42b, 44b, 47b, 48b are connected. Each of the solenoid operated valves 31b to 34b, 36b, 37b,
The springs 42b, 44b, 47b, and 48b are urged toward the oil discharge side (the transmission cutoff side) by springs. When these are electrically operated to the supply side, the pilot hydraulic oil is switched to the switching valves 31a to 34.
a, 36a, 37a, 42a, 44a, 47a, 48a
And these are operated on the supply side (transmission side).

(3) Next, the forward and reverse clutches 5,
6. The configuration of the operation unit such as the main transmission 10 will be described. As shown in FIG. 2 and FIG. 3, an opening / closing valve 51 capable of draining the pilot hydraulic oil from the operating portions of the switching valves 36a, 37a of the forward and reverse clutches 5, 6 is provided, and the opening / closing valve 51 is closed by a spring. And a clutch pedal 52 for mechanically operating the on-off valve 51 to the open side. Front wheel 19
A steering lever 58 for transmitting an electric forward signal and a reverse signal is provided at the base of the steering handle 58 for the vehicle.

As shown in FIG. 2, a speed change lever 28 is swingably supported around a horizontal axis of a control portion of the aircraft, and slides a shift member 53 of the second auxiliary transmission 12 (see FIG. 1). The shift fork 54 to be operated and the shift lever 28 are mechanically linked by a linkage mechanism 55,
When the shift lever 28 is in the neutral stop position N (corresponding to the shift position),
The second sub-transmission 12 is shifted to a lower position L (corresponding to a shift position) and a higher position H (corresponding to a shift position). A pair of limit switches 9 for detecting that the speed change lever 28 is operated to the low speed position L and the high speed position H are provided.

A lock pin 56 (corresponding to a lock mechanism) is provided on the side of the shift lever 28 so as to be movable up and down.
An operation button 57 for moving the lock pin 56 up and down
(Corresponding to a lock mechanism) is provided above the speed change lever 28. The lock pin 56 is urged by a spring (not shown) so as to move to a fixed position above the plane of the drawing (the operation button 57 is also urged to the left projecting side on the plane of the drawing).
By engaging the lock pin 56 with the fixed-side guide plate 60, the shift lever 28 is held at each of the neutral stop position N, the low-speed position L, and the high-speed position H. Operation button 57
When the push-in operation is performed, the lock pin 56 is moved to the holding release position below the paper surface, and the shift lever 28 can be operated to the neutral stop position N, the low speed position L, and the high speed position H.

A shift-up button 61 and a shift-down button 62 are vertically arranged on the left lateral side of the shift lever 28. When the shift-up button 61 and the shift-down button 62 are pressed once as described later, one shift is performed. Up signal and shift down signal are transmitted,
The speed change operation of the main and first auxiliary transmissions 10 and 11 shown in FIG. 1 is performed.

As shown in FIG. 2, a seven-segment shift display portion 64 for displaying shift positions (first to eighth speeds) of the main and first subtransmissions 10, 11 and a forward / reverse clutch 59 by a forward / reverse lever 59. A forward lamp 65 and a reverse lamp 66 for indicating which of the transmissions 5 and 6 is being operated on the transmission side;
A neutral stop lamp 67 that indicates that the shift lever 28 has been operated to the neutral stop position N is provided on the control unit.
As shown in FIG. 3, a pressure sensor 74 for detecting whether or not the operating pressure of the forward and reverse clutches 5, 6 has reached a predetermined pressure in the transmission state is provided.
The forward and backward lamps 65 and 66 are turned on by the detection of the number 4.

(4) Next, the shifting operation by the shift up button 61 and the shift down button 62 of the shift lever 28 will be described with reference to FIG. When the forward / reverse lever 59 shown in FIG. 2 is operated to the forward position F (step S1), an operation current is supplied to the electromagnetically operated valve 36b shown in FIG. 3 (step S2), and the switching valve 36a is operated to the supply side. Then, the forward clutch 5 is operated to the transmission side, and the forward lamp 65 is turned on (step S3). Conversely, when the forward / reverse lever 59 is operated to the reverse position R (step S
1), an operation current is supplied to the electromagnetic operation valve 37b shown in FIG. 3 (step S4), the switching valve 37a is operated on the supply side, the reverse clutch 6 is operated on the transmission side, and the reverse lamp 66 is operated.
Lights up (step S5), and the buzzer 71 shown in FIG. 2 operates intermittently (step S6).

As shown in FIG. 1, the main transmission 10 can shift up to four speeds and the first subtransmission 11 can shift up to two speeds. Step shifting is possible. In this case, the first auxiliary transmission 1
With the first low speed clutch 26 being operated on the transmission side, the first to fourth speed clutches 21 to 24 of the main transmission 10 correspond to the first to fourth speed shift positions. 11 in the state where the high-speed clutch 27 is operated on the transmission side, the first- to fourth-speed clutches 21 to 2 of the main transmission 10 are operated.
4 corresponds to the fifth to eighth speed shift positions.

[0034] As shown in FIG.
Each of the fourth-speed clutches 21 to 24 and the low-speed and high-speed clutches 26 and 27 of the first auxiliary transmission 11 is provided with a pressure sensor 74 for detecting whether or not these operating pressures have reached a predetermined pressure in the transmission state. The current shift positions (1st to 8th speed) of the main and first subtransmissions 10 and 11 are detected by the detection of each pressure sensor 74, and the detected shift positions are displayed on the shift display section 64. (Step S7).

In the above state, the shift lever 28 shown in FIG.
Is operated to the low-speed position L or the high-speed position H (step S8), it is assumed that the shift-up button 61 or the shift-down button 62 of the shift lever 28 is pressed once (steps S9, S10). In this case, FIG.
As shown by the solid line A1 (time point B1), when the shift-up button 61 is pressed, the solenoid-operated valves 31b to 34b for the main transmission 10 at the shift position one step higher than the current shift position. When the operation current starts to be supplied to the gear shifter and the shift-down button 62 is pressed, on the contrary, the electromagnetically operated valves 31b to 34b for the main transmission 10 at the shift position one step lower than the current shift position. , The operation current starts to be supplied (step S11).

At the same time, the solid line A2 in FIG. 5 (time B1)
As shown in the figure, the electromagnetic proportional valves 38 and 39 of the low-speed or high-speed clutches 26 and 27 that are operated on the transmission side in the first auxiliary transmission 11 allow the low-speed or high-speed clutches 26 and 27 that are operated on the transmission side to be operated. The operating pressure is reduced from the operating pressure P2 in the transmission state to a predetermined low pressure P3 (step S12). In this case, at the time of the shift operation from the fourth gear position to the fifth gear position, the operating pressure of the low speed clutch 26 of the first auxiliary transmission 11 is reduced to zero, and the high speed clutch 2
The operation pressure of the operating pressure of the pressure 7 is increased from zero to a predetermined low pressure P3. Conversely, during a shift operation from the fifth speed shift position to the fourth speed shift position, the operating pressure of the high speed clutch 27 of the first auxiliary transmission 11 is reduced to zero, and the operating pressure of the low speed clutch 26 is reduced from zero to a predetermined low pressure. The operation is raised to P3.

As shown by the solid line A1 in FIG. 5 (from time B2 to time B3), the operating pressure of the first-speed to fourth-speed clutches 21 to 24 on the first-stage high-speed side or the first-stage low-speed side in the main transmission 10 is reduced. The operation pressure is increased to the operating pressure P1 in the transmission state by the solenoid operated valves 31b to 34b. At the same time, FIG.
As indicated by the alternate long and short dash line A3 (from the time point B2 to the time point B3), the operating pressures of the first to fourth-speed clutches 21 to 24 before the pressing operation of the shift-up button 61 or the shift-down button 62 in the main transmission 10 are reduced Operation valves 31b to 34
In step S13, the operation pressure is decreased from the operating pressure P1 in the transmission state to zero (step S13).

Next, the first low pressure P3 maintained at the predetermined low pressure P3
The operating pressure of the low-speed or high-speed clutches 26, 27 of the auxiliary transmission 11 is gradually increased by the electromagnetic proportional valves 38, 39 as shown by the solid line A2 (time B3 to time B4) in FIG. The operating pressure of the low-speed or high-speed clutches 26, 27 reaches the operating pressure P2 in the transmission state (step S1).
4). In this case, from the time point B3 to the time point B4 of the solid line A2 shown in FIG. 5, the characteristic of increasing the operating pressure of the low-speed or high-speed clutches 26 and 27 is set for each shift position.
From the time point B3 to the time point B,
The operating pressure of 4 is rapidly increased in a short time.

As described above, the shift up button 6
One shift operation by pressing the 1 or downshift button 62 is ended. When the shift operation is completed, the shift position after the shift operation is displayed on the shift display section 64 (step S15), and the buzzer 71 is operated once. And the operator is notified of the end of the shift operation (step S16). The shift operation as described above is not performed continuously even if the shift-up button 61 or the shift-down button 62 is kept pressed, and the shift-up button 61 or the shift-down button 62 is returned once and pressed again. Otherwise, the next one shift operation is not performed.

(5) Next, when the shift lever 69 of the third auxiliary transmission 63 is operated to the deceleration position (ON),
Regarding the shift operation of the shift lever 28 of the second auxiliary transmission 12 to the neutral stop position N, the low speed position L, and the high speed position H,
Explanation will be given based on FIG. As shown in FIG. 2, a shift lever 69 mechanically linked to a shift fork (not shown) of a shift member 68 of the third auxiliary transmission 63 is provided. The third auxiliary transmission 63 is provided with the second auxiliary transmission 12.
At the same speed position (O
FF) and a deceleration position (ON) 2 where the power from the second auxiliary transmission 12 is greatly reduced to set an extremely low speed running state.
The shift lever 69 is configured to be able to perform a shift operation in a state.
Is provided with a limit switch 70 (corresponding to a discriminating means) for detecting that is operated to the deceleration position (ON).

[0041] Thus, as shown in FIG. 2, for example speed
When the lever 69 is operated to the deceleration position (ON), the shift lever 28 is operated to the low speed position L, and the forward / reverse lever 59 is operated to the forward position F (the forward clutch 5 is operated to the transmission side, The reverse clutch 6 is operated to the transmission cut-off side), the second shift position (the second speed clutch 22 of the main transmission 10 and the low speed of the first auxiliary transmission 11) are operated by the upshift button 61 and the downshift button 62. It is assumed that the vehicle is running with the clutch 26 being operated on the transmission side).

In the above state, the clutch pedal 52
, The forward clutch 5 is operated to the transmission cutoff side to stop the machine. Thereafter, the operation button 57 of the shift lever 28 is pressed (released) to release the lock pin 5.
6 is removed from the guide plate 60 downward (time point C).
1) The second speed clutch 22 of the main transmission 10 and the low speed clutch 26 of the first auxiliary transmission 11 are operated to the transmission interruption side. The forward clutch 5 has already been operated to the transmission cutoff side by depressing the clutch pedal 52.
Even if the clutch pedal 52 is returned while the button 7 is being pressed, the forward clutch 5 is held on the transmission cutoff side. At the same time, the first-speed and fourth-speed clutches 21 and 24 of the main transmission 10 are operated to the transmission side (time points C1, C
2) (corresponding to first control means).

As described above, in the state where the forward clutch 5 shown in FIG. 1 is operated to the transmission cutoff side, the power of the engine 1 is reduced via the forward clutch 5 due to the entrainment phenomenon of the forward clutch 5. It is assumed that the power is transmitted to the main transmission 10 little by little. In this case, the first and fourth speed clutches 21 and 24 in the main transmission 10 are operated to the transmission side, and the main transmission 10 is shifted to the first and fourth speed clutches 2.
Since the transmission is in a double transmission state with different transmission ratios at 1 and 24, and the braking is applied, the power is stopped in the main transmission 10 and the rotation phenomenon in the forward clutch 5 is also stopped. Therefore, in a state where power is not transmitted to the shift member 53 of the second auxiliary transmission 12, the shift lever 28 is lightly moved from the low speed position L to the neutral stop position N in a state where the operation button 57 is pressed (released). Can operate.

When the shift lever 28 is operated to the neutral stop position N and then the operation button 57 is returned (operation C3) (time point C3), the shift lever 28 is held at the neutral stop position N by the lock pin 56. The first-speed and fourth-speed clutches 21 and 24 of the main transmission 10 are operated to the transmission interruption side,
The original second speed clutch 22 of the main transmission 10, the original low speed clutch 26 and the original forward clutch 5 of the first auxiliary transmission 22
Is operated to the transmission side (corresponding to the second control means).

Next, after operating the shift lever 28 to the neutral stop position N, the operation button 57 is pressed again (release of holding).
Then, as described above, the second speed clutch 2 of the main transmission 10 is operated.
2. The low speed clutch 26 and the forward clutch 5 of the first auxiliary transmission 11 are operated to the transmission cutoff side,
The first and fourth speed clutches 21 and 24 are operated to the transmission side (time points C4 and C5) (corresponding to the first control means). When the shift lever 28 is operated to the neutral stop position N, the operation button 57
Is held in the state where the button is pressed (released), the second speed clutch 22 of the main transmission 10 and the first subtransmission 11
The low-speed clutch 26 and the forward clutch 5 of the first transmission and the fourth-speed clutch 2
The state where 1, 24 are operated on the transmission side is maintained.

As described above, in the main transmission 10,
By operating the high-speed and fourth-speed clutches 21 and 24 to the transmission side,
The power is stopped in the main transmission 10 as described above,
The rotation phenomenon in the forward clutch 5 is also stopped. In this case, since the low-speed and high-speed clutches 26 and 27 of the first sub-transmission 11 shown in FIG. 1 are operated to the transmission interruption side, the lower side (the front wheel 19 and the rear
On the other hand, the transmission shaft on the fourth side is stopped (due to the stoppage of the machine body), whereas the transmission shaft on the better side (on the side of the first auxiliary transmission 11) is stopped in a freely rotatable state.

Thus, when the shift lever 53 is operated from the neutral stop position N to the high-speed position H while the operation button 57 is pressed (released), the phase of the occlusion portion is adjusted. If the shift member 53 is not slid, the second auxiliary transmission 12
, The transmission shaft on the upper side (the side of the first auxiliary transmission 11) slightly rotates to match the phase, the shift lever 28 can be lightly operated from the neutral stop position N to the high speed position H, and the shift member 53
Can be occluded.

Next, when the shift lever 28 is operated to the high-speed position H and then the operation button 57 is returned (operation C6), the shift lever 28 is held at the high-speed position H by the lock pin 56. In this case, the aforementioned shift lever 28
Is different from the state in which the operation button 57 is returned to the neutral stop position N and the operation button 57 is operated (held).
The first-speed and fourth-speed clutches 21 and 24 of 0 are operated to the transmission interruption side, and the original second-speed clutch 22 of the main transmission 10 and the original low-speed clutch 26 of the first auxiliary transmission 11 are operated to the transmission side. (Time point C6), the forward clutch 5 is not yet operated to the transmission side.

The original second speed clutch 22 of the main transmission 10,
When the original low-speed clutch 26 of the first auxiliary transmission 11 is almost completely operated to the transmission side (time point C7), the forward clutch 5 is gradually operated to the transmission side. in this case,
As shown in FIGS. 1 and 2, the forward and reverse clutches 5, 6
A rotation speed sensor 73 for detecting the rotation speed of the cylindrical shaft 7 is provided between the transmission 10 and the main transmission 10. The detection value of the rotation speed sensor 73 starts at a time point C 7 when the forward clutch 5 starts operating on the transmission side. Figure 3 so that the rate of rise does not exceed the set value.
The operation pressure of the forward clutch 5 is increased by the electromagnetic proportional valve 35 shown in (1), and is operated on the transmission side to start the aircraft smoothly (time point C8).

At the aforementioned time point C7, the clutch pedal 5
2, the forward clutch 5 is held on the transmission cutoff side by the on-off valve 51 and the switching valve 36a shown in FIG. Therefore, by slowly returning the clutch pedal 52 after the time point C8, the forward clutch 5 can be artificially operated on the transmission side to smoothly start the machine.

(6) In the preceding paragraph (5) and FIG. 6, the first-speed shift position (the first-speed clutch 21 of the main transmission 10 and the low-speed clutch 26 of the first auxiliary transmission 11) are operated on the transmission side. When the above operation is performed in (state), the time point C
At 1 and C4, while the first-speed clutch 21 is operated on the transmission side, the fourth-speed clutch 24 is operated on the transmission side, and the double transmission state appears. The state of the time points C6 to C8 shown in FIG. 6 also occurs when the shift lever 28 is operated from the neutral stop position N to the low speed position L.

5th to 8th speed shift positions (first to fourth speed clutches 21 to 24 of main transmission 10 and first subtransmission 1
(The first high-speed clutch 27 is being operated on the transmission side.)
When the above-described operation is performed, the high-speed clutch 27 of the first auxiliary transmission 11 is operated to the transmission interruption side at the time points C1 and C4. In a state in which the forward / reverse lever 59 is operated to the reverse position R (a state in which the reverse clutch 6 is operated on the transmission side and the forward clutch 5 is operated on the transmission cutoff side), the reverse clutch 6 is turned on at the time points C1 and C4. Operated to the transmission cutoff side. At time points C1 and C4 shown in the preceding paragraph (5) and FIG. 6, the first-speed and second-speed clutches 21, 22, the second-speed and third-speed clutches
Speed clutches 22 and 23, 3rd speed and 4th speed clutches 23,
24 to the transmission side, and 1st to 4th speed clutches 21 to 21
All of 24 may be operated on the transmission side.

(7) Next, the neutral stop position N of the transmission lever 28 of the second auxiliary transmission 12 when the transmission lever 69 of the third auxiliary transmission 63 is operated to the same speed position (OFF). The shift operation to the low-speed position L and the high-speed position H will be described with reference to FIG. As shown in FIG. 7, the shift lever 69 is operated to the same speed position (OFF),
8 is being operated to the low-speed position L, for example, when the operation button 57 is pressed (released) (time point D).
1) The lock pin 56 is removed from the guide plate 60 and operated. At the same time, the solenoid operated valve 36 shown in FIG.
The forward or reverse clutches 5, 6 are operated to the transmission cut-off side by b, 37b, and the low-speed or high-speed clutches 26, 27 of the first auxiliary transmission 11 are operated to the transmission cut-off side by the electromagnetic proportional valves 38, 39.

Thus, the shift lever 28 is operated from the low speed position L to the neutral stop position N while the operation button 57 is pressed (released). In this case, as shown in FIG. 1, since the low-speed and high-speed clutches 26 and 27 of the first sub-transmission 11 immediately above the second sub-transmission 12 are operated to the transmission cut-off side, the neutralization by the transmission lever 28 is performed. The shift operation to the stop position N can be easily performed.

After operating the shift lever 28 to the neutral stop position N and then returning (operating) the operation button 57 (time point D2), the shift lever 28 is held at the neutral stop position N by the lock pin 56, and at the same time, The forward or reverse clutches 5, 6 are immediately operated to the transmission side by the solenoid operated valves 36b, 37b and the solenoid proportional valve 35 shown in FIG. 3, and the low speed or high speed clutch 26 of the first auxiliary transmission 11 is operated by the solenoid proportional valves 38, 39. , 27 are immediately moved to the transmission side.

Next, when the operation button 57 is pressed (released) at the time when the shift lever 28 is operated to the neutral stop position N (time point D3), the lock pin 56 is moved downward from the guide plate 60 in the same manner as described above. And the forward or reverse clutches 5, 6 and the low-speed or high-speed clutches 26, 27 of the first auxiliary transmission 11 are operated to the transmission interruption side.
Thus, for example, when the shift lever 28 is operated from the neutral stop position N to the high-speed position H in a state where the operation button 57 is pressed (released), similarly to the above-described case, Since the low-speed and high-speed clutches 26 and 27 of the first subtransmission 11 are operated on the transmission blocking side, the shift operation to the high-speed position H by the shift lever 28 can be easily performed.

After operating the shift lever 28 to the high-speed position H, when the operator releases the operation pin 57 and releases it (holds) (time point D4), the shift lever 28 is held at the high-speed position H by the lock pin 56. At the same time, the low-speed or high-speed clutches 26, 27 of the first auxiliary transmission 11 are immediately operated to the transmission side by the electromagnetic proportional valves 38, 39. On the other hand, the forward or reverse clutches 5 and 6 are moved from the time point D4 when the operation button 57 is returned (operated) to the rotation speed sensor 7 in a manner similar to the case from the time point C7 to the time point C8 shown in FIG.
In order to prevent the rate of increase of the detected value of the third clutch 3 from exceeding the set value, the electromagnetic clutch 35 shown in FIG.
The operating pressure of No. 6 is operated to increase, and is operated to the transmission side (time point D5).

Incidentally, reference numerals are written in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the attached drawings by the entry. Further, the traveling speed change structure of a work vehicle according to the present invention may be a traveling speed change method of a work vehicle.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a transmission system in a transmission case.

FIG. 2 is a diagram showing a linked state of a shift lever and a second auxiliary transmission, a shift display section and a linked state of each section.

FIG. 3 is a hydraulic circuit diagram of a main transmission, a first auxiliary transmission, and the like.

FIG. 4 is a diagram showing a flow of a shift operation by a shift up button and a shift down button of a shift lever.

FIG. 5 is a diagram showing a state of each part at the time of a shift operation by a shift up button and a shift down button of a shift lever.

FIG. 6 is a diagram showing a state of each part when the second sub-transmission is operated by the shift lever and the operation button when the third sub-transmission is operated to shift to the deceleration position;

FIG. 7 is a diagram illustrating a state of each part when the second sub-transmission is operated by the shift lever and the operation button when the third sub-transmission is operated to shift to the same speed position.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine 5, 6 Main clutch 10 Main transmission 11 First auxiliary transmission 12 Second auxiliary transmission 14, 19 Traveling device 21, 22, 23, 24 Hydraulic clutch of main transmission 26, 27 For first auxiliary transmission Hydraulic clutch 28 Transmission lever of second auxiliary transmission 31b, 32b, 33b, 34b Control valve of main transmission 53 Shift member of second auxiliary transmission 56, 57 Locking mechanism of transmission lever 63 Third auxiliary transmission 68 Third Shift member of sub-transmission 70 Identification means L, N, H Shift position of shift lever

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-229470 (JP, A) JP-A-54-20528 (JP, A) Jpn. Field (Int.Cl. ⁷ , DB name) F16H 61/26-61/36 F16H 63/00-63/38

Claims (2)

(57) [Claims] An engine (1) receives power from an engine (1) using hydraulic multiple disc type main clutches (5) and (6), a main transmission (10), a first auxiliary transmission (11), and a second auxiliary transmission (12). ) And the third sub-transmission (63) in this order to perform a speed change operation and transmit the transmission to the lower traveling devices (14) and (19). 1 auxiliary transmission (11)
To a plurality of multi-plate hydraulic clutches (21), (2)
2), (23), (24), (26), and (27) are arranged in parallel, and the plurality of hydraulic clutches (21), (2)
2) a hydraulic clutch type in which a speed change operation is performed by supplying hydraulic oil to one of (23), (24), (26), and (27) and operating it on the transmission side; The second auxiliary transmission (12) and the third auxiliary transmission (6
3) is configured as a gear shift type in which the shift operation is performed by sliding the shift members (53) and (68), and the shift member (53) and the shift lever (2) of the second auxiliary transmission (12) are configured.
8) and the speed change lever (2).
8) The second sub-transmission (12) is configured to perform a shift operation, and the determination means (70) that determines whether the third sub-transmission (63) is being shifted to a lower speed side. ), While the third sub-transmission (63) is being shifted to a lower speed based on the discrimination by the discriminating means (70), using the speed-change lever (28) of the second sub-transmission (12). When the speed change operation is started, the hydraulic clutches (26) and (27) of the main clutches (5) and (6) and the first sub-transmission (11) are operated to the transmission interruption side accordingly. A first control means for operating two or more hydraulic clutches (21), (24) of the main transmission (10) on the transmission side; and a transmission lever (28) of the second auxiliary transmission (12). With the end of the shift operation, the first subtransmission (1
One predetermined hydraulic clutch (26) in 1) is operated on the transmission side, and the hydraulic clutches (21) and (24) operated on the transmission side in the main transmission (10) are operated on the transmission cutoff side. And a predetermined one hydraulic clutch (22)
To the transmission side and the main clutch (5),
A traveling speed change structure for a working vehicle, comprising: a second control means for allowing the operation to the transmission side of (6). 2. Lock mechanisms (56), (57) capable of holding and releasing the shift lever (28) of the second auxiliary transmission (12) at each of the shift positions (L), (N), (H). ), The operation of the lock mechanisms (56), (57) toward the holding release side is set as the start of the speed change operation by the speed change lever (28), and the third auxiliary transmission (63) is set to the low speed side. The lock mechanisms (56), (5)
7) is operated such that the first control means starts operating when the lock mechanism (56), (5) is operated to the release side.
2. The traveling speed change structure for a working vehicle according to claim 1, wherein said first control means and said first control means are linked.