JP2003314679A - Traveling gear shifting structure for working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decrease shock in a traveling gear shifting structure for a working vehicle wherein a transmission clutch is automatically operated into a disengaged state, and the transmission clutch is automatically operated into an engaged state again after operating a gear shifting mechanism by an actuator. <P>SOLUTION: A first controlling means is provided, which operates a second gear shifting mechanism 15 at a specified gear shifting position, operates a first friction clutch 9 into the disengaged state while operating a second friction clutch 12 into the engaged state, and operates the transmission clutch 6 from the engaged state to a semi-engaged state and gradually into the engaged state. A second controlling means is provided, which operates a first gear shifting mechanism 13 at a specified gear shifting position, operates the second friction clutch 12 into the disengaged state while operating the first friction clutch 9 into the engaged state, and operates the transmission clutch 6 from the engaged state to the semi-engaged state and gradually into the engaged state. A third controlling means is provided, which obtains the gear shifting position due to a gear shifting command by alternately actuating the first and second controlling means. <P>COPYRIGHT: (C)2004,JPO

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 work vehicle equipped with a gear speed change mechanism, based on a speed change command.
The present invention relates to a device having a configuration in which a transmission clutch is automatically operated in a disengaged state, a gear shift mechanism is operated by an actuator, and the transmission clutch is automatically operated in a transmission state again.

[0002]

2. Description of the Related Art An example of a traveling speed change structure for a work vehicle as described above is disclosed in Japanese Patent Laid-Open No. 6-313478. In the structure of the publication, a gear transmission mechanism (A in FIG. 1 of the publication) operated by an actuator (T1, T2 in FIG. 1 of the publication), and a hydraulic multi-plate transmission clutch (FIG. 1 of the publication). 19) is arranged in series. As a result, the transmission clutch is automatically operated in the disengaged state based on the shift command, and the gear shift mechanism is operated by the actuator. When the operation of the gear shift mechanism by the actuator is completed, the transmission clutch is automatically and gradually operated into the transmission state.

Generally, a work vehicle is subject to a large traveling load, such as when traveling on a soft ground having a large traveling resistance or when towing a truck carrying a load. If the transmission clutch is operated in the disengaged state during the operation, the power of the engine is not transmitted to the traveling device at this point, and the traveling speed of the airframe may suddenly decrease due to the traveling load. As a result, when the traveling speed of the machine is greatly reduced at the end of the operation of the gear shift mechanism by the actuator and the power of the engine flows to the traveling device when the transmission clutch is operated in the transmission state as described above, The aircraft may be suddenly accelerated to the traveling speed of and shock may occur.

On the other hand, according to the structure of the publication, an auxiliary transmission clutch (E in FIG. 1 of the publication) is provided which bypasses the transmission clutch and can transmit the power of the gear transmission mechanism to the lower side. As a result, when the transmission clutch is operated to the disengaged state as described above, the auxiliary transmission clutch is operated from the disengaged state to the transmission state, and the power of the gear shift mechanism is transmitted to the lower side through the auxiliary transmission clutch. The reduction of the traveling speed of the aircraft due to the traveling load can be suppressed. When the operation of the gear shift mechanism by the actuator is completed and the transmission clutch is operated in the transmission state, the auxiliary transmission clutch is operated from the transmission state to the disengaged state. In this way, the state in which the airframe is rapidly accelerated to the original traveling speed before the decrease is suppressed, and the occurrence of shock is prevented.

[0005]

According to the structure described in the prior art, while the transmission clutch is operated in the disengaged state and the gear transmission mechanism is operated by the actuator, the power of the gear transmission mechanism is auxiliary transmission. When the power is transmitted to the lower side through the clutch, the transmission ratio of the power transmitted through the auxiliary transmission clutch is substantially constant (the transmission ratio of the gear at the left end of the paper in the gear reduction mechanism A in FIG. 1 of the above publication). ).

As a result, for example, in a higher speed range than the transmission ratio of the power transmitted through the auxiliary transmission clutch (for example, the transmission ratio of the shift position before and after the shift is transmitted through the auxiliary transmission clutch). When the gear shift is performed as described in the prior art when the gear ratio is higher than the gear ratio of the above), the power is transmitted at the gear ratio of the high speed shift position, and then the low gear ratio of the auxiliary transmission clutch is changed. Then, the power is transmitted, and the power is transmitted again at the transmission ratio of the high speed shift position, which may cause a shock.
The present invention, in the traveling speed change structure of a work vehicle, automatically operates the transmission clutch to the disengaged state based on the speed change command, operates the gear transmission mechanism by the actuator, and again automatically operates the transmission clutch to the transmission state. In the case of such a configuration, the purpose is to reduce shock when shifting.

[0007]

[I] According to the features of claim 1 (claims 2 and 3), an upper hand side transmission shaft for transmitting engine power and a lower hand side transmission for transmitting power to a traveling device. A first transmission system and a second transmission system are arranged in parallel with the shaft, and a hydraulic multi-plate type transmission clutch is provided on the transmission upper side or the lower transmission side of the first and second transmission systems. The power of the side transmission shaft is transmitted to the lower transmission shaft through one of the first and second transmission systems. A first transmission system including a first gear transmission mechanism having a plurality of transmission positions between the upper or lower transmission shaft and the first transmission system, and a first actuator for operating the first gear transmission mechanism; Is equipped with a first friction clutch. A second transmission system including a second gear transmission mechanism having a plurality of shift positions between the upper or lower transmission shaft and the second transmission system, and a second actuator for operating the second gear transmission mechanism; Is equipped with a second friction clutch.

As a result, claim 1 (claims 2 and 3)
According to the feature of (1), the power is transmitted through the first transmission system (the first gear transmission mechanism is operated to a predetermined gear position,
When the gear shift command is issued while the first friction clutch is being operated in the transmission state), the second actuator operates the second gear speed change mechanism to a predetermined gear shift position so that the second friction clutch is released. The first friction clutch is operated from the transmission state to the disengaged state while being operated to the transmission state, and during this period, the transmission clutch is operated from the transmission state to the semi-transmission state and gradually moved to the transmission state (first Control means).

On the contrary, a state in which power is transmitted through the second transmission system (the second gear speed change mechanism is operated to a predetermined speed change position,
In a state where the second friction clutch is operated in the transmission state), when the gear shift command is issued, the first gear shift mechanism is operated to the predetermined gear shift position by the first actuator, and the first friction clutch is released. The second friction clutch is operated from the transmission state to the disengagement state while being operated to the transmission state, and during this period, the transmission clutch is operated from the transmission state to the semi-transmission state and gradually to the transmission state (second Control means).

[II] As described in the above item [I], according to the features of claim 1 (claims 2 and 3), the second friction clutch is switched from the disengaged state to the transmitted state while the gear shifting operation is performed. When the first friction clutch is operated from the transmission state to the disengagement state while being operated, the second friction clutch is operated from the transmission state to the disengagement state while the first friction clutch is operated from the disengagement state to the transmission state. By doing so, the power of the upper transmission shaft is branched and transmitted to both the first and second transmission systems, and the power of the first and second transmission systems merges with the lower transmission shaft (double transmission state). Occurs. Even if torque fluctuation occurs in the double transmission state, the transmission clutch in the semi-transmission state slips to some extent to absorb the torque variation, and the power with less torque variation is transmitted to the traveling device.

As described above, according to the features of claim 1 (claims 2 and 3), a double transmission state is generated while the gear shifting operation is performed, and the power with less torque fluctuation is transmitted to the traveling device. Therefore, it is possible to prevent the traveling speed of the aircraft from decreasing due to the traveling load while the gear shifting operation is being performed. As a result, it is possible to prevent a state in which the traveling speed of the machine body is drastically reduced due to the traveling load and the transmission clutch is operated in the transmission state to cause a shock when the traveling speed of the machine body is significantly reduced.

In this case, according to the features of claim 1 (claims 2 and 3), since the first and second gear shift mechanisms have a plurality of shift positions, when a double transmission state is generated,
When the power is transmitted through the first transmission system (the first gear transmission mechanism is operated to a predetermined gear position and the first friction clutch is operated to the transmission state), the second gear transmission mechanism is operated. It is possible to operate from a plurality of shift positions to an appropriate shift position. A state in which power is transmitted via the second transmission system (the second gear transmission mechanism is operated to a predetermined gear position,
In a state where the second friction clutch is operated in the transmission state), the first gear transmission mechanism can be operated to an appropriate shift position from a plurality of shift positions. As a result, as described in [Problems to be Solved by the Invention], the state in which the power is transmitted at the transmission ratio at the high speed shift position is changed to the state at which the power is transmitted at the low transmission ratio, and the high speed is resumed. The state in which power is transmitted at the transmission ratio of the gear shift position and a shock is generated is prevented.

[III] According to the feature of claim 1, the first and second control means are alternately operated from the shift position before the shift command is issued to the shift position according to the shift command so that the shift position according to the shift command is changed. The third control means is provided so as to be obtained. Thus, according to the feature of claim 1, from the gear shift position before the gear shift command is issued to the gear shift position according to the gear shift command, the occurrence of the double transmission state and the torque fluctuation as described in [I] and [II] above. The transmission of less motive power to the traveling device is repeated, and a gear shift operation with less shock is performed from the gear shift position before the gear shift command is issued to the gear shift position according to the gear shift command.

[IV] As described in the above [III],
When the first and second control means are alternately operated from the shift position before the shift command is issued to the shift position according to the shift command, the shift position before the shift command is issued until the shift position according to the shift command is reached. It may take a relatively long time.

In this case, according to the second aspect of the invention, an intermediate shift position having a transmission ratio substantially intermediate between the shift position before the shift command is issued and the shift position according to the shift command is set,
One of the first and second control means is operated so that the intermediate shift position is obtained from the shift position before the shift command is issued, and the first or second control means is operated to obtain the shift position according to the shift command from the intermediate shift position. A third control means for activating the other of the second control means is provided. According to the feature of claim 3, the intermediate shift position is set slightly closer to the shift position before the shift command is issued from the shift position according to the shift command, and the intermediate shift position is obtained from the shift position before the shift command is issued. So as to operate one of the first or second control means, and to operate the other of the first or second control means so as to obtain the shift position according to the shift command from the intermediate shift position. ing.

Thus, according to the feature of claim 2 (claim 3), the first and second control means are not operated alternately from the shift position before the shift command is issued to the shift position according to the shift command. , The gear shift operation is performed from the gear shift position before the gear shift command is issued to the intermediate gear shift position, and the gear shift operation is performed from the intermediate gear shift position to the gear shift position according to the gear shift command. It is possible to make the time from when the gear shift command reaches the shift position by the shift command relatively short.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION [1] FIG. 1 shows a traveling transmission system of a four-wheel drive type agricultural tractor which is an example of a work vehicle.
The power of the engine 1 is transmitted to the transmission shaft 2 and then to the PTO shaft 3. Cylindrical transmission shafts 4 and 5 are fitted onto the transmission shaft 2 so as to be rotatable relative to each other, and a hydraulic multi-plate friction type transmission clutch 6 is provided between the transmission shafts 4 and 5. The transmission clutch 6 is configured to be in a transmission state by supplying hydraulic oil, and to be in a cutoff state by discharging hydraulic oil.

As shown in FIG. 1, a first main transmission shaft 7 and a first sub transmission shaft 8 are arranged in parallel with the transmission shafts 2 and 4, and
A first friction clutch 9 is provided between the main and auxiliary transmission shafts 7 and 8. A second main transmission shaft 10 and a second sub transmission shaft 11 are arranged in parallel with the transmission shafts 2 and 4, and a second friction clutch 12 is provided between the second main and sub transmission shafts 10 and 11. The first and second friction clutches 9 and 12 are of a hydraulic multi-plate friction type and are operated in a transmission state by supplying hydraulic oil, and in a cut-off state by discharging hydraulic oil. Is configured to.

As shown in FIG. 1, a synchromesh type first gear speed change mechanism 13 is provided between the transmission shaft 2 and the first main transmission shaft 7 to connect the transmission shaft 2 and the second main transmission shaft 10. A synchromesh type second gear transmission mechanism 15 is provided between them. A first gear 17, a second gear 18, a third gear 19, and a fourth gear 20 are fixed to the transmission shaft 2, and a low-speed gear 21 and a high-speed gear externally fitted to the first main transmission shaft 7 so as to be rotatable relative to each other. 22 meshes with the first gear 17 and the third gear 19,
The shift member 23 has a spline structure so that the first main transmission shaft 7
The first gear speed change mechanism 13 is configured by being externally fitted to the shaft so as to be integrally rotatable and slidable. The low-speed gear 24 and the high-speed gear 25, which are fitted onto the second main transmission shaft 10 so as to be rotatable relative to each other, engage with the second gear 18 and the fourth gear 20, and the shift member 2
6 is externally fitted to the second main transmission shaft 10 by a spline structure so as to be integrally rotatable and slidable.
Is configured.

As shown in FIG. 1, a synchromesh type first auxiliary gear speed change mechanism 14 is provided between the transmission shaft 4 and the first auxiliary transmission shaft 8, and the transmission shaft 4 and the second auxiliary transmission shaft 11 are connected to each other. A second auxiliary gear speed change mechanism 16 of a synchromesh type is provided between the two. The transmission shaft 4 has a low speed gear 27 and a high speed gear 2.
8 is fixed, and the low speed gear 29 and the high speed gear 30, which are fitted onto the first sub-transmission shaft 8 so as to be relatively rotatable, are the low speed gear 2 and the low speed gear 2.
7 and the high-speed gear 28, and the shift member 31 is externally fitted to the first sub transmission shaft 8 so as to be integrally rotatable and slidable by the spline structure, thereby forming the first sub gear transmission mechanism 14. The low-speed gear 32 and the high-speed gear 33, which are fitted onto the second sub-transmission shaft 11 relatively rotatably, mesh with the low-speed gear 27 and the high-speed gear 28, and the shift member 34 rotates integrally with the second sub-transmission shaft 11 by the spline structure. Also, the second auxiliary gear speed change mechanism 16 is configured to be slidably fitted on the outer side.

With the above structure, the power of the transmission shaft 2 is transmitted to the transmission shaft 4 via the first main and auxiliary transmission shafts 7 and 8 (first friction) as described in [3] below. Clutch 9
And a state in which the power of the transmission shaft 2 is transmitted to the transmission shaft 4 via the second main and auxiliary transmission shafts 10 and 11 (transmission state of the second friction clutch 12). As shown in FIG. 1, the power of the transmission shaft 2 is the first main and auxiliary transmission shafts 7 and 8.
In the state of being transmitted to the transmission shaft 4 via the transmission (the transmission state of the first friction clutch 9), the power of the transmission shaft 2 is transmitted to the first gear transmission mechanism 13, the first main transmission shaft 7, the first friction clutch 9, and the first friction clutch 9. It is transmitted to the transmission shaft 4 after being changed in four stages through the first sub transmission shaft 8 and the first sub gear transmission mechanism 14 (first speed position, which will be described later, 3
Speed position, 5th speed position, 7th speed position). As shown in FIG. 1, when the power of the transmission shaft 2 is transmitted to the transmission shaft 4 via the second main and auxiliary transmission shafts 10 and 11 (transmission state of the second friction clutch 12), Power is the second gear transmission 1
5, the second main transmission shaft 10, the second friction clutch 12, the second sub-transmission shaft 11 and the second sub-gear speed change mechanism 16, and the speed is changed in four stages and transmitted to the transmission shaft 4 (second speed described later). position,
(4th speed position, 6th speed position, 8th speed position).

[2] As shown in FIG. 1, a cylindrical transmission shaft 43 is provided on the lower side of the transmission shaft 5, and a synchromesh type forward / reverse switching mechanism is provided between the transmission shaft 5 and the transmission shaft 43. 44 are provided. A transmission shaft 45 is provided on which the transmission shaft 43 is fitted so as to be rotatable relative to the transmission shaft 43.
5, a sub-transmission mechanism 46 of the synchromesh type is provided. A front wheel transmission shaft 55 that transmits power to the front wheels 53 is provided, and a hydraulic clutch type front wheel transmission mechanism 56 is provided between the transmission shaft 45 and the front wheel transmission shaft 55.

As shown in FIG. 1, a forward gear 47 and a reverse gear 48 are fixed to the transmission shaft 43, and a forward gear 49 externally fitted to the transmission shaft 5 rotatably relative to each other meshes with the forward gear 47 to form a transmission shaft. A reverse gear 50 that is externally fitted to the gear 5 to allow relative rotation.
Meshes with the reverse gear 48 via the intermediate gear 51,
The shift member 52 is externally fitted to the transmission shaft 5 so as to be integrally rotatable and slidable by the spline structure, and the forward / reverse switching mechanism 4
4 are configured. As shown in FIG. 2, the shift member 5
2 is provided with a forward / reverse lever 57 mechanically linked to
The forward / reverse switching mechanism 44 is operated by operating the forward / reverse lever 57 to the forward drive position F and the reverse drive position R and sliding the shift member 52 to engage the forward drive gear 49 and the reverse drive gear 50.

As shown in FIG. 1, the sub-transmission mechanism 46 is constructed so that it can be operated at a high speed position, a medium speed position and a low speed position by slidingly operating two shift members. The front wheel transmission mechanism 56 is configured to be operable in a standard state in which the front wheels 53 and the rear wheels 54 are driven at the same speed, and in a speed increasing state in which the front wheels 53 are driven at a higher speed than the rear wheels 54.

With the above structure, the power of the transmission shaft 5 is transmitted to the rear wheel 54 through the forward / reverse switching mechanism 44, the auxiliary transmission mechanism 45, the transmission shaft 45 and the rear wheel differential mechanism 58 in the straight traveling state. The front wheel transmission mechanism 56, the front wheel transmission shaft 55, and the front wheel differential mechanism 59 in which the power of the auxiliary transmission mechanism 46 is in the standard state.
It is transmitted to the front wheel 53 via. When the front wheels 53 are steered to the right or left around the straight-ahead position, the front wheel speed change mechanism 56 is operated from the standard state to the speed increasing state, the front wheels 53 are driven at a higher speed than the rear wheels 54, and a small turn smoothly. Done.

[3] As shown in FIGS. 1 and 2, in the first gear speed change mechanism 13, the first actuator 35 and the first actuator 35 of the double-acting hydraulic cylinder type for sliding the shift member 23 are operated. A control valve 39 for supplying and discharging oil is provided, and in the first sub-gear speed change mechanism 14, the first sub-actuator 36 and the first sub-actuator 36 of a double-acting hydraulic cylinder type for sliding the shift member 31 are operated. A control valve 40 for supplying and discharging oil is provided. The first actuator 35 is the shift member 23.
Is engaged with the low speed gear 21, the low speed position L, the shift member 23
Is configured to be operable in a high speed position H and a neutral position N in which it engages with the high speed gear 22, and the first auxiliary actuator 36
Is configured to be operable at a low speed position L where the shift member 31 engages with the low speed gear 29 and a high speed position H where the shift member 31 engages with the high speed gear 30.

As shown in FIGS. 1 and 2, in the second gear speed change mechanism 15, a second actuator 37 of a double-acting hydraulic cylinder type for slidingly operating the shift member 26,
The second actuator 37 is provided with a control valve 41 for supplying and discharging hydraulic oil, and in the second auxiliary gear speed change mechanism 16, the second auxiliary actuator 38 of the double-acting hydraulic cylinder type for sliding the shift member 34 is provided. The secondary actuator 38 is provided with a control valve 42 for supplying and discharging hydraulic oil. The second actuator 37 is configured to be operable at a low speed position L in which the shift member 26 meshes with the low speed gear 24, a high speed position H in which the shift member 26 meshes with the high speed gear 25, and a neutral position N. Is configured to be operable at a low speed position L in which the shift member 34 meshes with the low speed gear 32 and a high speed position H in which the shift member 34 meshes with the high speed gear 33.

As shown in FIG. 2, a control valve 60 of the electromagnetic proportional pressure reducing valve type for supplying / discharging operating oil to the transmission clutch 6 and an electromagnetic proportional pressure reducing valve type for supplying / discharging operating oil to the first friction clutch 9 are used. A control valve 61 and a control valve 62 of the electromagnetic proportional pressure reducing valve type for supplying and discharging hydraulic oil to and from the second friction clutch 12 are provided.

With the above structure, as shown in FIGS. 1 and 7, the power of the transmission shaft 2 is transmitted to the transmission shaft 4 via the first main and auxiliary transmission shafts 7 and 8 (first friction clutch). 9, the low speed position L of the shift member 31 is the first speed position, and the low speed position L of the shift member 23 is the first speed position.
At the low speed position L, the high speed position H of the shift member 23 is at the third speed position, the high speed position H of the shift member 31 is at the low speed position L of the shift member 23 at the fifth speed position, and the high speed position H of the shift member 31 is at the high speed position of the shift member 23. The position H becomes the 7th speed position. 1 above
In the third speed position and the third speed position, the second friction clutch 12 is operated in the disengaged state, the shift member 26 is in the neutral position N, and the shift member 34 is in the low speed position L. In the 5th and 7th speed positions, the second friction clutch 12 is operated in the disengaged state, the shift member 26 is in the neutral position N, and the shift member 34 is in the high speed position H.

As shown in FIGS. 1 and 7, the power of the transmission shaft 2 is transmitted to the transmission shaft 4 via the second main and auxiliary transmission shafts 10 and 11 (transmission state of the second friction clutch 12). At the low speed position L of the shift member 34,
The low speed position L is the second speed position, and the low speed position L of the shift member 34 is
The high speed position H of the shift member 26 is the fourth speed position, the high speed position H of the shift member 34 is the low speed position L of the shift member 26 is the sixth speed position, and the high speed position H of the shift member 34 is the high speed position H of the shift member 26. It is in the fast position. At the above-mentioned second and fourth speed positions, the first friction clutch 9 is operated in the disengaged state,
The shift member 23 is in the neutral position N and the shift member 31 is in the low speed position L. 1st in 6th and 8th positions
The friction clutch 9 is operated in the disengaged state, and the shift member 23
Is in the neutral position N, and the shift member 31 is in the high speed position H.

[4] Next, the control of the shift operation will be described. This agricultural tractor has four modes, namely, a first speed change mode, a second speed change mode, a third speed change mode, and a fourth speed change mode. When the driver operates the setting switch 65 (see FIG. 2), the first speed change mode is set. One of the shift mode, the second shift mode, the third shift mode, and the fourth shift mode is selected.

As shown in FIG. 2, a shift lever 63 and a setting switch 65 which can be freely operated are provided at the 1st to 8th speed positions. The shift lever 63 and the setting switch 65 are operated, and the forward / backward lever 57 is operated. Is input to the control device 64. The control device 61 operates the shift lever 63 and the setting switch 65, the forward and backward lever 57,
Based on the first to fourth shift modes, the control valves 39, 40,
41, 42, 60, 61, 62 are operated to operate the first actuator 35, the first sub actuator 36, the second actuator 37, and the second sub actuator 38,
The transmission clutch 6, the first friction clutch 9, and the second friction clutch 12 are operated in the transmission and disengaged states.

First, the first shift mode will be described.
In the first speed change mode, when the speed change lever 63 is operated from one operation position (speed change position) to another operation position (speed change position), the speed change is performed from the operation position (speed change position) before the operation of the speed change lever 63. The gear shift operation is performed all at once to the operation position (gear shift position) where the lever 63 has been operated.

As shown in FIGS. 3 and 7, it is assumed that, for example, the speed change lever 63 is operated to the first speed position and then the speed change lever 63 is operated to the second speed position. When the shift lever 63 is operated to the 1st speed position, the shift member 3
1 is at the low speed position L, the shift member 23 is at the low speed position L, the transmission clutch 6 and the first friction clutch 9 are operated in the transmission state at the operating pressure P1, and the shift member 34 is at the low speed position L.
When the shift member 26 is in the neutral position N, the second friction clutch 12
Is operated in the shut-off state with the operating pressure P0.

As shown in FIG. 3, when the speed change lever 63 is operated to the first speed position and the speed change lever 63 is operated to the second speed position (time T11), the transmission clutch 6 and the first clutch
The friction clutch 9 is quickly depressurized to the operating pressure P0 and is operated in the disengaged state (see the solid line A3 and the alternate long and short dash line A1), and the second friction clutch 12 is quickly increased to the operating pressure P1 and is operated in the transmission state ( (See dotted line A2). At the same time, the shift member 23 is operated from the low speed position L to the neutral position N, and the shift member 26 is operated from the neutral position N to the low speed position L (the shift members 31 and 34 are held at the low speed position L). .

As shown in FIG. 3, when the shift member 23 is operated from the low speed position L to the neutral position N and the shift member 26 is operated from the neutral position N to the low speed position L (time point T1).
2) Then, the transmission clutch 6 is gradually increased from the operation pressure P0 to reach the operation pressure P1 (see the solid line A3), and the transmission clutch 6 is operated in the transmission state (time point T13). The gear shifting operation is completed as described above. In this case, the time T1 required for one shift operation (from time T11 to time T13)
Is relatively short.

For example, when the speed change lever 63 is operated from the second speed position to the first speed position, as shown in FIG.
3, 26 (the shift members 31, 34 are held at the low speed position L) are operated, the first
And, the states of the second friction clutches 9 and 12 are reversed, and the first friction clutch 9 is operated from the disengaged state to the transmission state.
The friction clutch 12 is operated from the transmission state to the disengagement state, and as shown by the solid line A3 in FIG.
Depressurization and pressurization are performed.

For example, when the speed change lever 63 is operated from the first speed position to the third speed position, as shown in FIG.
Is operated, the shift member 26 remains in the neutral position N (the shift members 31 and 34 are held in the low speed position L), the first friction clutch 9 is held in the transmission state, and the second
The friction clutch 12 is held in the disengaged state, and the pressure reduction and pressure increase of the transmission clutch 6 are performed as indicated by the solid line A3 in FIG.

For example, when the speed change lever 63 is operated from the 2nd speed position to the 4th speed position, as shown in FIG.
Is operated, the shift member 23 remains in the neutral position N (the shift members 31 and 34 are held at the low speed position L), the first friction clutch 9 is held in the disengaged state, and
The friction clutch 12 is held in the transmission state, and the pressure reduction and the pressure increase of the transmission clutch 6 are performed as indicated by the solid line A3 in FIG.

[5] Next, the first half of the second speed change mode will be described with reference to FIGS. In the second speed change mode, when the speed change lever 63 is operated from one operation position (speed change position) to another operation position (speed change position), the operation position (speed change position) before the operation of the speed change lever 63 is changed to 1 The shifting operation is performed one by one, and finally the shifting lever 6
The gear shift operation is performed so as to reach the operated position (gear shift position) of No. 3. For example, when the speed change lever 63 is operated from the first speed position to the fifth speed position, the speed change operation from the first speed position to the second speed position is performed, the speed change operation from the second speed position to the third speed position is performed, and the third speed position is performed. From the 4th gear position to the 4th gear position, and from the 4th gear position to the 5th gear position. For example, when the speed change lever 63 is operated from the 6th speed position to the 3rd speed position, the speed change operation from the 6th speed position to the 5th speed position is performed, and the speed change operation from the 5th speed position to the 4th speed position is performed. The shift operation from the to the 3rd speed position is performed.

For example, the state in which the speed change lever 63 is operated to the first speed position (the shift member 23 is in the low speed position L, the shift member 26 is in the neutral position N, the shift members 31 and 34 are in the low speed position L, the transmission clutch 6 and the first clutch). The friction clutch 9 operates at the operating pressure P.
When the transmission lever 63 is in the transmission state and the second friction clutch 12 is operated in the disengaged state with the operating pressure P0), for example, the transmission lever 63 is operated to the fifth speed position (step S1) (time point T).
21), the shift member 26 is operated from the neutral position N to the low speed position L (steps S2 and S3) (time T21 to time T22). As a result, the shift members 23 and 31 are in the first speed position, and the shift members 26 and 34 are in the second speed position. In this case, the shift member 34 is left at the low speed position L without being operated at the high speed position H (passes through step S4).
(See Figure 7).

When the shift member 26 is operated to the low speed position L (the second speed position) (step S3) (time point T2).
2), the transmission clutch 6 operates with the operating pressure P2 (operating pressures P0, P1
The pressure is quickly reduced in the middle (between the two) to operate in the semi-transmission state (step S5) (time point T22) (see the solid line A3). At about the same time, the second friction clutch 12 is relatively quickly increased in pressure from the operating pressure P0 and is operated in the transmission state (from time point T22 to time point T23) (see dotted line A2), while the first friction clutch 9 is operated at the operating pressure P1. Is relatively quickly depressurized and operated to shut off (step S6).
(Time T22 to time T23) (see the alternate long and short dash line A1).

As a result, the power when the shift members 23 and 31 are in the first speed position is transmitted to the transmission shaft 4, and at the same time, the power when the shift members 26 and 34 are in the second speed position is transmitted. A double transmission state is generated in which the torque is transmitted to and merges with each other. Therefore, even if the torque varies in the double transmission state, the transmission clutch 6 in the semi-transmission state slips to some extent to absorb the torque variation and Is transmitted to the front wheels 53 and the rear wheels 54.

When the second friction clutch 12 is operated in the transmission state with the operating pressure P1 and the first friction clutch 9 is operated in the disengaged state with the operating pressure P0 (time point T23), the shift member 23 is operated.
Is operated to the neutral position N (step S7) (time point T2).
3 to time point T24). In this case, the shift member 31 is left at the low speed position L without being operated at the high speed position H (passes step S8) (see FIG. 7). When the shift member 23 is operated to the neutral position N (time T24), the transmission clutch 6 is gradually increased from the operating pressure P2 to reach the operating pressure P1 and is operated in the transmission state (step S9) (from time T24). Time point T25). As described above, the shift operation from the first speed position to the second speed position is completed.

[6] Next, the latter half of the second speed change mode will be described with reference to FIGS. When the gear shifting operation from the 1st speed position to the 2nd speed position as described in the above item [5] is completed, the process proceeds from step S16, S2 to step S10, and the shift members 26, 34 are in the 2nd speed position. The members 23 and 31 are operated to the third speed position (step S10). In this case, the shift member 31 is at the high speed position H.
Is left at the low speed position L without being operated (step S11).
(See FIG. 7). The transmission clutch 6 has an operating pressure P2.
The pressure is quickly reduced to an intermediate value between the operating pressures P0 and P1 and is operated in a semi-transmission state (step S12), and at the same time as this, the first friction clutch 9 is boosted relatively quickly from the operating pressure P0. While being operated in the power transmission state, the second friction clutch 12 is depressurized relatively quickly from the operating pressure P1 and is operated in the disengaged state (step S13).

As a result, the power when the shift members 26 and 34 are in the second speed position is transmitted to the transmission shaft 4, and at the same time, the power when the shift members 23 and 31 are in the third speed position is transmitted. A double transmission state is generated in which the torque is transmitted to and merges with each other. Therefore, even if the torque varies in the double transmission state, the transmission clutch 6 in the semi-transmission state slips to some extent to absorb the torque variation and Is transmitted to the front wheels 53 and the rear wheels 54.

When the first friction clutch 9 is operated in the transmission state at the operating pressure P1 and the second friction clutch 12 is operated in the disengaged state at the operating pressure P0, the shift member 26 is operated to the neutral position N (step). S14). In this case, the shift member 34 is left at the low speed position L without being operated at the high speed position H (passes step S15) (see FIG. 7). Shift member 2
When 6 is operated to the neutral position N, the transmission clutch 6 is gradually increased from the operating pressure P2 to reach the operating pressure P1 and is operated in the transmission state (step S9). As described above,
The shift operation from the second gear position to the third gear position is completed.

When the shift operation from the second gear position to the third gear position is completed as described above, the shift members 23 and 31 are in the third gear position and the shift members 26 and 34 are in the fourth gear position. Shifting from the 4th speed position to the 4th speed position is the same as the previous item [5].
And steps S2 to S9 (in this case,
The shift members 34 and 31 are not operated to the high speed position H and are left at the low speed position L (passes steps S4 and S8) (FIG. 7).
reference).

Next, the shift operation from the 4th speed position to the 5th speed position when the shift members 26 and 34 are in the 4th speed position and the shift members 23 and 31 are in the 5th speed position is described in this item [6] and step. This is performed based on S2, S10 to S15, and S9 (in this case, in step S11, the shift member 31
Is operated from the low speed position L to the high speed position H, and the shift member 34 is operated from the low speed position L to the high speed position H in step S15) (see FIG. 7). When the shift operation is repeated as described above and the operating position (shift position) of the shift lever 63 is reached (step S16), the shift operation ends.

[7] Next, the first half of the third speed change mode will be described with reference to FIGS. 6 and 7. In the third shift mode, when the shift lever 63 is operated from one operation position (shift position) to another operation position (shift position), the operation position before the shift lever 63 is operated (shift position)
And the operation position (gear position) at which the gear shift lever 63 is operated.
Between the first and second intermediate shift positions (first and second intermediate shift positions) having a transmission ratio of approximately intermediate, the first intermediate shift position from the operating position (shift position) before the shift lever 63 is operated. The shift operation to the position is performed, and the shift operation is performed from the first intermediate shift position to the operation position (shift position) where the shift lever 63 is operated (the operation position before the shift lever 63 is operated (shift position ) To the first intermediate shift position, a shift operation from the first intermediate shift position to the second intermediate shift position is performed, and the shift lever 63 is operated from the second intermediate shift position. A shift operation to (shift position) is performed.

When the speed change lever 63 is operated from one operation position (speed change position) to one of the high speed side or low speed side operation position (for example, when the speed change lever 63 is operated from the first speed position to the second speed position or the eighth speed position). From the 7th gear position),
After shifting from steps S21, S22, and S23 to step S29, the shift operation of the shift lever 63 to the operation position (shift position) is performed. In this case, if the operation position (gear position) before the gear shift lever 63 is operated is the first, third, fifth, and seventh speed positions, the preceding item [5] and steps S3 to S9 in FIG.
If the operation position (gear position) before the gear shift lever 63 is operated is the second, fourth, sixth, and eighth speed positions, the gear shift operation is performed based on [6] and steps S10 to S1 in FIG.
5, the shift operation based on S9 is performed.

When the speed change lever 63 is operated to the 1st, 3rd, 5th, and 7th speed positions while the speed change lever 63 is operated to another 1st, 3rd, 5th, and 7th speed position (steps S21, S22), the speed change lever 63 The operating position (shift position) before was operated,
A first intermediate shift position having a substantially intermediate transmission ratio among the second, fourth, sixth, and eighth speed positions is set between the shift lever 63 and the operated position (shift position) (step S2).
4). For example, when the shift lever 63 is operated from the 1st speed position to the 7th speed position, the 4th speed position is set as the first intermediate shift position.

When the speed change lever 63 is operated to the second, fourth, sixth and eighth speed positions while the speed change lever 63 is operated to the second, fourth, sixth and eighth speed positions (steps S21 and S23), the speed change lever 63 is operated. The operating position (shift position) before was operated,
A first intermediate shift position having a transmission ratio substantially intermediate among the first, third, fifth and seventh speed positions is set between the shift lever 63 and the operation position (shift position) (step S2).
4). For example, when the shift lever 63 is operated from the eighth gear position to the second gear position, the fifth gear position is set as the first intermediate gear shift position.

When the speed change lever 63 is operated to the second, fourth, sixth and eighth speed positions with the speed change lever 63 being operated to the first, third, fifth and seventh speed positions (as described above, the speed change lever 63 is set to a certain operation position). (Excluding the case of operating from the (shift position) to the one operating position on the high speed side or the low speed side) (steps S21 and S2)
2) between the operation position (shift position) before the shift lever 63 is operated and the operation position (shift position) where the shift lever 63 is operated, among the second, fourth, sixth and eighth speed positions. A first intermediate shift position with a substantially intermediate transmission ratio is set,
Of the third, fifth and seventh speed positions, the second intermediate shift position having a substantially intermediate transmission ratio is set (step S26). In this case, the second intermediate shift position is closer to the operation position (shift position) where the shift lever 63 is operated with respect to the first intermediate shift position.
For example, when the speed change lever 63 is operated from the first speed position to the sixth speed position, the third speed position is set as the first intermediate speed change position, and
The speed position is set as the second intermediate shift position. For example, if the shift lever 63 is operated from the 1st speed position to the 8th speed position, 4
The speed position is set as the first intermediate shift position, and the fifth speed position is set as the second intermediate shift position.

When the transmission lever 63 is operated to the 1, 3, 5 and 7th speed positions while the transmission lever 63 is operated to the 2nd, 4th, 6th and 8th speed positions (as described above, the transmission lever 63 is operated to a certain operating position). (Excluding the case of operating from the (shift position) to the one operating position on the high speed side or the low speed side) (steps S21 and S2)
3) Between the operating position (shift position) before the shift lever 63 is operated and the operating position (shift position) where the shift lever 63 is operated, among the first, third, fifth and seventh speed positions. The first intermediate shift position with a substantially intermediate transmission ratio is set,
Of the fourth, sixth, and eighth speed positions, the second intermediate shift position having a substantially intermediate transmission ratio is set (step S26). In this case, the second intermediate shift position is closer to the operation position (shift position) where the shift lever 63 is operated with respect to the first intermediate shift position.
For example, when the shift lever 63 is operated from the 8th speed position to the 1st speed position, the 5th speed position is set as the first intermediate shift position, and
The speed position is set as the second intermediate shift position.

[8] Next, the latter half of the third speed change mode will be described with reference to FIGS. 6 and 7. As described in [7] above, in the state where the first intermediate shift position is set (step S24), shifting from the operating position (shift position) before the shift lever 63 is operated to the first intermediate shift position The operation is performed (step S25). In this case, the operation position (shift position) before the shift lever 63 is operated is 1,
At the third, fifth and seventh speed positions, the gear shift operation is performed based on the preceding item [5] and steps S3 to S9 of FIG. 5, and the operation position (gear position) before the gear shift lever 63 is operated is 2,4. ，
If it is in the 6th or 8th speed position, the gear shift operation is performed based on the preceding item [6] and steps S10 to S15 and S9 of FIG.

Next, the shift lever 6 is moved from the first intermediate shift position.
A gear shift operation is performed to the operation position (gear shift position) where 3 is operated (step S29). In this case, if the first intermediate shift position is the first, third, fifth, and seventh speed positions, the shift operation based on the preceding item [5] and steps S3 to S9 of FIG. 5 is performed,
When the first intermediate shift position is the second, fourth, sixth, or eighth speed position, the shift operation is performed based on the preceding item [6] and steps S10 to S15 and S9 of FIG.

As described in the above item [7], the first and second
In the state where the intermediate shift position is set (step S2
6) A shift operation is performed from the operating position (shift position) before the shift lever 63 is operated to the first intermediate shift position (step S27). In this case, if the operation position (shift position) before the shift lever 63 is operated is the first, third, fifth, and seventh speed positions, the preceding item [5] and steps S3 to S in FIG.
When the gear shift operation based on 9 is performed and the operation position (gear shift position) before the gear shift lever 63 is operated is the second, fourth, sixth, and eighth speed positions, the above item [6] and steps S10 to S1 in FIG. 5 are performed.
5, the shift operation based on S9 is performed.

Next, a shift operation from the first intermediate shift position to the second intermediate shift position is performed (step S28). In this case, if the first intermediate shift position is the first, third, fifth, and seventh speed positions, the shift operation based on the preceding item [5] and steps S3 to S9 of FIG. 5 is performed, and the first intermediate shift position is 2 ,. 4, 6, 8
If it is in the high speed position, the above step [6] and step S10 in FIG.
The gear shift operation is performed based on steps S15 and S9.

Next, the shift lever 6 is moved from the second intermediate shift position.
A gear shift operation is performed to the operation position (gear shift position) where 3 is operated (step S29). In this case, if the second intermediate shift position is the first, third, fifth, and seventh speed positions, the shift operation based on the previous item [5] and steps S3 to S9 of FIG. 5 is performed,
If the second intermediate shift position is the second, fourth, sixth, or eighth speed position, the shift operation is performed based on the preceding item [6] and steps S10 to S15, S9 of FIG.

[9] Next, the fourth shift mode will be described. In the fourth shift mode, as in the third shift mode described in [7] and [8], the first intermediate shift position (first shift position)
And the second intermediate shift position) is set, but the first intermediate shift position (first and second intermediate shift positions) is set as follows.
Different from the shift mode.

In the fourth shift mode, the shift lever 6
3 is operated from one operation position (gearshift position) to another operation position (gearshift position), from the operation position (gearshift position) at which the gearshift lever 63 was operated to the operation position before the gearshift lever 63 is operated ( The first intermediate shift position (first and second intermediate shift positions) slightly closer to the shift position) is set, and the first intermediate shift position (shift position) is set to the first shift position before the shift lever 63 is operated.
An operation position (shift position) in which the shift lever 63 is operated from the first intermediate shift position when the shift operation to the intermediate shift position is performed.
To the first intermediate shift position from the operating position (shift position) before the shift lever 63 is operated to shift from the first intermediate shift position to the second intermediate shift position. The gear shift operation is performed, and the gear shift operation from the second intermediate gear shift position to the operation position (gear shift position) where the gear shift lever 63 is operated is performed.

When the shift lever 63 is operated from one operation position (shift position) to one of the high speed side and the low speed side operation position (for example, when the shift lever 63 is operated from the first speed position to the second speed position or the eighth speed position). From the 7th gear position),
Similarly to the third shift mode (see [7] above), the shift operation to the operation position (shift position) of the shift lever 63 is performed.
In this case, if the operation position (shift position) before the shift lever 63 is operated is the first, third, fifth, and seventh speed positions, the shift operation based on the preceding item [5] and steps S3 to S9 of FIG. 5 is performed. If the operating position (shift position) before the shift lever 63 is operated is the second, fourth, sixth, and eighth speed positions, the shift operation based on the previous item [6] and steps S10 to S15, S9 of FIG. Done.

When the speed change lever 63 is operated to the 1, 3, 5, 7th speed position and the speed change lever 63 is operated to another 1, 3, 5, 7th speed position, the operation position at which the speed change lever 63 is operated. The first intermediate shift position, which is slightly shifted from the (shift position) to the operation position (shift position) before the shift lever 63 is operated, is set from the second, fourth, sixth, and eighth speed positions. For example, when the shift lever 63 is operated from the first speed position to the seventh speed position, the sixth speed position is set as the first intermediate shift position.

When the speed change lever 63 is operated to the second, fourth, sixth, and eighth speed positions while the speed change lever 63 is operated to another second, fourth, sixth, and eighth speed positions, the operation position at which the speed change lever 63 is operated. The first intermediate shift position, which is slightly shifted from the (shift position) to the operation position (shift position) before the shift lever 63 is operated, is set from the 1, 3, 5, and 7th speed positions. For example, when the shift lever 63 is operated from the eighth gear position to the second gear position, the third gear position is set as the first intermediate gear shift position.

When the speed change lever 63 is operated to the second, fourth, sixth and eighth speed positions while the speed change lever 63 is operated to the first, third, fifth and seventh speed positions (as described above, the speed change lever 63 is set to a certain operation position). (Except when operated to one operation position on the high speed side or low speed side from (shift position)), from the operation position (shift position) at which the shift lever 63 is operated to the operation position before the shift lever 63 is operated ( The first intermediate shift position slightly closer to the (shift position) is set from the second, fourth, sixth and eighth speed positions,
The second intermediate shift position slightly deviated from the operation position (shift position) where the shift lever 63 is operated to the operation position (shift position) before the shift lever 63 is operated is 1, 3, 5, 7
It is set from the fast position. In this case, the second intermediate shift position is closer to the operation position (shift position) where the shift lever 63 is operated with respect to the first intermediate shift position. For example, when the shift lever 63 is operated from the 1st speed position to the 8th speed position, the 6th speed position is set as the first intermediate shift position and the 7th speed position is set as the 2nd intermediate position.

When the speed change lever 63 is operated to the second, fourth, sixth and eighth speed positions and the speed change lever 63 is operated to the first, third, fifth and seventh speed positions (as described above, the speed change lever 63 is set to a certain operation position). (Except when operated to one operation position on the high speed side or low speed side from (shift position)), from the operation position (shift position) at which the shift lever 63 is operated to the operation position before the shift lever 63 is operated ( The first intermediate shift position, which is slightly closer to the shift position), is set from among the 1, 3, 5, and 7th speed positions,
The second intermediate shift position slightly deviated from the operation position (shift position) where the shift lever 63 is operated to the operation position (shift position) before the shift lever 63 is operated is 2, 4, 6, 8
It is set from the fast position. In this case, the second intermediate shift position is closer to the operation position (shift position) where the shift lever 63 is operated with respect to the first intermediate shift position. For example, when the shift lever 63 is operated from the eighth gear position to the first gear position, the third gear position is set as the first intermediate gear shift position and the second gear position is set as the second middle gear position.

When the first intermediate shift position (first and second intermediate shift positions) is set as described above, the above [8]
Similarly to the third shift mode shown in FIG. 6, the shift operation from the operating position (shift position) before the shift lever 63 is operated to the first intermediate shift position, the shift lever 63 from the first intermediate shift position is changed. The gear shift operation to the operated operation position (shift position) is performed, and the shift operation from the operation position (shift position) before the shift lever 63 is operated to the first intermediate shift position, the first intermediate shift position From the second intermediate shift position to the operation position (shift position) where the shift lever 63 is operated from the second intermediate shift position.

[10] Next, the case where the forward / reverse lever 57 is operated will be described. In the forward / reverse switching mechanism 44 as described in the above item [2], the forward / reverse lever 57 is mechanically linked to the shift member 52 as shown in FIG. 2, and the operation position of the forward / reverse lever 57 is input to the control device 64. The forward / reverse lever 57 slides the shift member 52 to the forward drive position F and the reverse drive position R.

As a result, when the forward / reverse lever 57 is started to be operated from the forward drive position F to the reverse drive position R (when the backward drive position R is started to be operated to the forward drive position F), the latter half of the above [4] (first shift mode) is performed. 3, the transmission clutch 6 is automatically decompressed and operated to the disengaged state as shown by the solid line A3 in FIG. 3, and the forward / reverse lever 57 is moved to the reverse position R (forward position F).
When it is operated to, the transmission clutch 6 is automatically and gradually increased in pressure and operated to the transmission state.

Only the transmission clutch 6 is provided with a clutch pedal (not shown) that can be manually stepped, and the operation position of the clutch pedal is input to the control device 64. Accordingly, when the clutch pedal is depressed, the control device 64 and the control valve 60 operate the transmission clutch 6 in the disengaged state, and when the clutch pedal is released, the control device 64 and the control valve 60 cause the transmission clutch 6 to be in the transmission state. Operated.

[Another Embodiment of the Invention] In the above-mentioned [embodiment of the invention], the transmission clutch 6 and the forward / reverse switching mechanism 44 shown in FIG. 1 may be arranged on the transmission shaft 2. Figure 1
Is formed between the first sub transmission shaft 8 and the transmission shaft 4, and the first sub gear transmission mechanism 14 is formed between the first main transmission shaft 7 and the transmission shaft 2. May be. The second gear transmission mechanism 15 shown in FIG. 1 is configured between the second sub transmission shaft 11 and the transmission shaft 4, and the second sub gear transmission mechanism 16 is disposed between the second main transmission shaft 10 and the transmission shaft 2. You may comprise. The present invention can be applied to a working vehicle including right and left crawler traveling devices instead of the front wheels 53 and the rear wheels 54.

[0073]

According to the features of claim 1 (claims 2 and 3), in the traveling speed change structure of a work vehicle, a double transmission state is generated while a speed change operation is performed, and power with less torque fluctuation is generated. Is transmitted to the traveling device, the traveling speed of the aircraft drastically decreases due to the traveling load, and when the traveling clutch of the aircraft is operated in the transmission state with the traveling speed of the aircraft greatly decreasing, a shock may occur. It was possible to prevent such a situation and improve the running performance and gear shifting performance of the work vehicle.

According to the features of claim 1 (claims 2 and 3), since the first and second gear shift mechanisms have a plurality of shift positions, when the double transmission state is generated, the second gear shift is performed. As described in [Problems to be Solved by the Invention], since the mechanism (first gear transmission mechanism) can be operated from a plurality of transmission positions to an appropriate transmission position,
From the state where power is transmitted at the transmission ratio at the high speed shift position, the power is transmitted at the transmission ratio at the low speed, and the power is transmitted again at the transmission ratio at the high speed shift position. It is possible to prevent the occurrence of the occurrence of the above, and it is possible to improve the running performance and shift performance of the work vehicle.

According to the feature of claim 1, from the shift position before the shift command is issued to the shift position according to the shift command,
By configuring the double transmission state and the transmission of power with less torque fluctuation to the traveling device to be repeated, a shift with less shock can be performed from the shift position before the shift command is issued to the shift position according to the shift command. As a result, the running performance and shifting performance of the work vehicle could be improved.

According to the features of claims 2 and 3, the shift operation is performed from the shift position before the shift command is issued to the intermediate shift position, and the shift operation is performed from the intermediate shift position to the shift position according to the shift command. As a result, it is possible to reduce the shock to some extent, and to make the time from the gear shift position before the gear shift command is issued to the gear shift position based on the gear shift command relatively short, and to improve the running performance and workability of the work vehicle. The gear shifting performance could be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a traveling transmission system.

FIG. 2 is a diagram showing an operation system of a forward / reverse lever, a speed change lever, a transmission clutch, first and second friction clutches, first and first auxiliary actuators, and second and second auxiliary actuators.

FIG. 3 is a diagram showing a gear shift operation from a first gear position to a second gear position in a first gear shift mode.

FIG. 4 is a diagram showing a shift operation from a first gear position to a second gear position in a second gear shifting mode.

FIG. 5 is a diagram showing a flow of a second shift mode.

FIG. 6 is a diagram showing a flow of a third shift mode.

FIG. 7 is a diagram showing states of a shift member and first and second friction clutches at first to eighth speed positions.

[Explanation of symbols]

1 engine 2 Good side transmission shaft 4 Lower transmission shaft 6 Transmission clutch 7,8 First transmission system 9 First friction clutch 10,11 Second transmission system 12 Second friction clutch 13 1st gear transmission 15 Second gear speed change mechanism 35 First Actuator 37 Second Actuator 53,54 traveling device

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hidetoshi Hana             64 Ishizukitamachi, Sakai City, Osaka Prefecture Kubo Co., Ltd.             Ta Sakai Factory (72) Inventor Isamu Kawai             64 Ishizukitamachi, Sakai City, Osaka Prefecture Kubo Co., Ltd.             Ta Sakai Factory (72) Inventor Takashi Yakaku             64 Ishizukitamachi, Sakai City, Osaka Prefecture Kubo Co., Ltd.             Ta Sakai Factory F term (reference) 3J028 EA21 EB08 EB09 EB37 FC32                       FC64 GA14 HB17 HC15                 3J057 AA04 BB04 FF07 FF10 FF12                       FF15 GA26 GA47 GB27 HH04                       HH05 JJ01 JJ04                 3J552 MA04 MA05 MA13 MA15 NA05                       NB01 PA02 RA02 SB01 SB33                       SB35 VA62Z

Claims (3)

[Claims] 1. A first transmission system and a second transmission system are arranged in parallel between an upper hand side transmission shaft for transmitting power of an engine and a lower hand side transmission shaft for transmitting power to a traveling device. , A hydraulic multi-plate type transmission clutch is provided on the transmission upper side or the transmission lower side of the first and second transmission systems, and the power of the upper side transmission shaft is transmitted through one of the first and second transmission systems. And a first gear transmission mechanism having a plurality of shift positions between the upper transmission shaft or the lower transmission shaft and the first transmission system. 1
A first actuator for operating the gear shifting mechanism,
The first transmission system is provided with a first friction clutch, and the second transmission system is provided with a second gear transmission mechanism having a plurality of transmission positions between the upper or lower transmission shaft and a second transmission system.
A second actuator for operating the gear shifting mechanism,
A second friction clutch is provided in the second transmission system, and in a state in which power is transmitted via the first transmission system, the second gear shift mechanism is operated to a predetermined shift position by the second actuator, The first friction clutch is operated from the transmission state to the disengagement state while the second friction clutch is operated from the disengaged state to the transmission state, and the transmission clutch is operated from the transmission state to the semi-transmission state and gradually to the transmission state. In a state in which power is transmitted via the first control means and the second transmission system, the first gear shift mechanism is operated to a predetermined shift position by the first actuator, and the first friction clutch is disengaged. The second friction clutch from the transmission state to the disengagement state while operating from the transmission state to the transmission state, and the transmission clutch from the transmission state to the semi-transmission state is gradually changed to the transmission state. So as to obtain the gear shift position according to the gear shift command by alternately operating the second control means and the first and second control means from the gear shift position before the gear shift command is issued to the gear shift position according to the gear shift command. And a third control means for controlling the traveling speed change structure of the work vehicle. 2. A first transmission system and a second transmission system are arranged in parallel between an upper-side transmission shaft for transmitting power of an engine and a lower-side transmission shaft for transmitting power to a traveling device. , A hydraulic multi-plate type transmission clutch is provided on the transmission upper side or the transmission lower side of the first and second transmission systems, and the power of the upper side transmission shaft is transmitted through one of the first and second transmission systems. And a first gear transmission mechanism having a plurality of shift positions between the upper transmission shaft or the lower transmission shaft and the first transmission system. 1
A first actuator for operating the gear shifting mechanism,
The first transmission system is provided with a first friction clutch, and the second transmission system is provided with a second gear transmission mechanism having a plurality of transmission positions between the upper or lower transmission shaft and a second transmission system.
A second actuator for operating the gear shifting mechanism,
A second friction clutch is provided in the second transmission system, and in a state in which power is transmitted via the first transmission system, the second gear shift mechanism is operated to a predetermined shift position by the second actuator, The first friction clutch is operated from the transmission state to the disengagement state while the second friction clutch is operated from the disengaged state to the transmission state, and the transmission clutch is operated from the transmission state to the semi-transmission state and gradually to the transmission state. In a state in which power is transmitted via the first control means and the second transmission system, the first gear shift mechanism is operated to a predetermined shift position by the first actuator, and the first friction clutch is disengaged. The second friction clutch from the transmission state to the disengagement state while operating from the transmission state to the transmission state, and the transmission clutch from the transmission state to the semi-transmission state is gradually changed to the transmission state. And a second control means for operating the gear shift command and a gear shift position before the gear shift command is issued by setting an intermediate gear shift position of a transmission ratio substantially intermediate between the gear shift position before the gear shift command is issued and the gear shift position by the gear shift command. One of the first and second control means is operated so that the intermediate shift position can be obtained from the position, and the first or second shift position can be obtained from the intermediate shift position by the shift command.
A traveling speed change structure for a work vehicle, comprising: a third control means for operating the other of the control means. 3. A first transmission system and a second transmission system are arranged in parallel between an upper hand side transmission shaft for transmitting power of an engine and a lower hand side transmission shaft for transmitting power to a traveling device. , A hydraulic multi-plate type transmission clutch is provided on the transmission upper side or the transmission lower side of the first and second transmission systems, and the power of the upper side transmission shaft is transmitted through one of the first and second transmission systems. And a first gear transmission mechanism having a plurality of shift positions between the upper transmission shaft or the lower transmission shaft and the first transmission system. 1
A first actuator for operating the gear shifting mechanism,
The first transmission system is provided with a first friction clutch, and the second transmission system is provided with a second gear transmission mechanism having a plurality of transmission positions between the upper or lower transmission shaft and a second transmission system.
A second actuator for operating the gear shifting mechanism,
A second friction clutch is provided in the second transmission system, and in a state in which power is transmitted via the first transmission system, the second gear shift mechanism is operated to a predetermined shift position by the second actuator, The first friction clutch is operated from the transmission state to the disengagement state while the second friction clutch is operated from the disengaged state to the transmission state, and the transmission clutch is operated from the transmission state to the semi-transmission state and gradually to the transmission state. In a state in which power is transmitted via the first control means and the second transmission system, the first gear shift mechanism is operated to a predetermined shift position by the first actuator, and the first friction clutch is disengaged. The second friction clutch from the transmission state to the disengagement state while operating from the transmission state to the transmission state, and the transmission clutch from the transmission state to the semi-transmission state is gradually changed to the transmission state. And a second control means to be operated, and an intermediate shift position slightly shifted from the shift position based on the shift command to the shift position before the shift command is issued, and the intermediate shift position from the shift position before the shift command is issued. One of the first or second control means is operated so as to obtain, and the other of the first or second control means is operated so as to obtain the shift position according to the shift command from the intermediate shift position. A traveling speed change structure for a work vehicle, comprising: a third control means.