JP3069274B2 - 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 continuously variable transmission operating device which is mechanically connected to a transmission unit of a continuously variable transmission for traveling. The present invention relates to a traveling speed change structure of a work vehicle configured to shift a speed of a transmission.

[0002]

2. Description of the Related Art An example of the traveling speed change structure of a work vehicle as described above is disclosed in Japanese Patent Laid-Open No. Hei 6-201007. In this structure, the transmission lever (16 in FIGS. 1 and 4 in the above-mentioned publication) (corresponding to the transmission operation tool), which is artificially operated in the reverse direction, is mechanically linked with the continuously variable transmission for traveling. The worm speed reduction mechanism (paragraph number [000
9]), the power of the electric motor (13 in FIGS. 1 and 4 of the above publication) is applied as an assist force in the forward and reverse directions along the operation direction of the shift lever. A switch (17, 18 in FIGS. 1 and 4 of the above-mentioned publication) (corresponding to an operation state detecting means) for detecting whether or not the shift lever is artificially operated, and for detecting the operating direction of the shift lever; When the speed change lever is artificially operated, an operation current is supplied to the electric motor so that an assist force is applied in the operation direction of the speed change lever.

[0003] By providing the electric motor with an assist force to the shift lever, the shift operation by the shift lever can be performed lightly. By providing the worm speed reduction mechanism, when the hand is released from the shift lever (the electric motor is stopped), the continuously variable transmission is held at the shift position even if the continuously variable transmission attempts to return to the low speed side. This eliminates the need for a dedicated friction holding mechanism that holds the continuously variable transmission at an arbitrary shift position.

[0004]

The speed reduction ratio of the worm speed reduction mechanism described above is very large, and even if the speed change operation device is operated prior to the assisting force of the electric motor, the speed change operation device is moved ahead by the worm speed reduction mechanism. Cannot be operated.

Accordingly, in the configuration in which the assist force is applied from the electric motor via the worm speed reduction mechanism to the speed change operation tool as described above, the operation of the speed change operation tool becomes slow, and the speed change operation tool is quickly operated to reduce the speed. It is no longer possible to say that the speed of the stepped transmission is shifted, and there is room for improvement in operability. SUMMARY OF THE INVENTION The present invention relates to a continuously variable transmission structure in which a speed change operation tool is quickly operated while maintaining the advantage that a dedicated friction holding mechanism for holding a continuously variable transmission at an arbitrary transmission position is unnecessary in a traveling speed change structure of a work vehicle. It is an object of the present invention to provide a configuration in which a shift operation of the device can be performed.

[0006]

[Means for Solving the Problems]

[I] According to the features of claim 1, an operation current is supplied to the electric motor based on the detection of the operation state detecting means in response to the manual operation of the speed change operation tool, and the power of the electric motor is applied to the speed change operation tool by the assist force. The speed change operation of the continuously variable transmission by the speed change operation tool can be performed lightly. Since the worm speed reduction mechanism is not provided in the feature of the first aspect, the operation force of the speed change operation tool is reversed by the electric motor in a normal state in which the power from the electric motor is applied to the speed change operation tool as assist force. You can also tell. Thus, if the shift operation tool is quickly operated against the resistance of the electric motor, the continuously variable transmission can be quickly shifted by the shift operation tool prior to the assisting force of the electric motor.

If the worm speed reduction mechanism is not provided, it cannot be expected that the continuously variable transmission will be held at the shift position while the hand is released from the shift operation tool (the electric motor is stopped). Therefore, according to the first aspect of the present invention, when the speed change operation tool is not operated artificially, a holding current is supplied to the electric motor, and a small assist force is applied to the speed change operation tool. As a result, the small assist force described above and the force for returning the continuously variable transmission to the low speed side are balanced, and the continuously variable transmission is held at the shift position.

In a continuously variable transmission for traveling of a work vehicle, a force for returning to a low speed side changes due to a traveling load applied to the body, and a force for returning to a low speed side increases as the traveling load increases. When the running load is reduced, the force for returning to the low speed side is reduced. Thus, the feature of claim 1 is provided with a load detecting means for detecting a running load applied to the body, and the holding current is supplied to the electric motor when the running load is large as described above. When the running load is small, no holding current is supplied to the electric motor. When the running load is small, the force that tends to return to the low speed side of the continuously variable transmission is small, so the mechanical resistance of the electric motor and the like can be reduced without supplying the holding current to the electric motor. , The continuously variable transmission is held at the shift position.

[II] According to the feature of the second aspect, similar to the case of the first aspect, it has the "action" described in the above-mentioned [I], and additionally has the following "action". ing. Generally, in a continuously variable transmission for traveling of a work vehicle,
It can be determined that the higher the speed of the continuously variable transmission, the greater the traveling load applied to the body. Therefore, by detecting the operation position of the speed change operation device for shifting the continuously variable transmission, the traveling load applied to the aircraft body can be detected.

[III] According to the feature of the third aspect, similar to the case of the first aspect, the "action" described in the above-mentioned [I] is provided, and in addition, the following "action" is provided. ing. In general, in a work vehicle, as the load applied to the body increases, the engine speed decreases in proportion to the load, and the slip in the continuously variable transmission increases. Thus, by detecting the engine speed as in the third aspect, it is possible to detect a decrease in the engine speed or slippage in the continuously variable transmission to detect the running load applied to the aircraft. .

[IV] According to the feature of claim 4, as in the case of claim 1, 2, or 3, the above-mentioned [I] or [II]
Or, it has the “action” described in [III], and additionally has the following “action”. If the aircraft is turned on uneven terrain, the running load applied to the aircraft will be large, so if the aircraft is continuously turned, a particularly large running load will be applied to the aircraft, and the engine speed will decrease. The force by which the transmission attempts to return to the low speed side becomes large. In such a state in which the body is continuously turned, when a holding current is supplied to the electric motor and the continuously variable transmission is to be held in the shift position, a traveling load applied to the body is set. May be further increased, causing the engine to stop.

Therefore, according to a feature of the present invention, if the turning state of the machine body continues for a set time, the holding current is not supplied to the electric motor. As a result, when the aircraft continues to turn, the force of the continuously variable transmission that attempts to return to the low speed side is large, and the continuously variable transmission is automatically shifted to the low speed side, and the traveling load applied to the aircraft is reduced. As a result, the stoppage of the engine is avoided.

[0013]

FIG. 4 shows a transmission system of a combine, which is an example of a working vehicle, in which power from an engine 1 is transmitted via a belt transmission mechanism 2 having a tension clutch.
The power is transmitted to the input pulley 4 of the belt-type continuously variable transmission 3. The power from the continuously variable transmission 3 is transmitted to the left and right crawler traveling devices 6 via a hydraulic clutch type forward / backward switching device (not shown) of the transmission case 5 and a traveling gear transmission (not shown). Is transmitted. The power separated from immediately before the gear transmission is transmitted from the transmission case 5 via the belt transmission mechanism 7 to the reaping unit 8 at the front of the machine body.

Next, the belt-type continuously variable transmission 3 and its shift operation structure will be described. As shown in FIG. 2, the first split pulley 1 is attached to the input shaft 9 to which the input pulley 4 is fixed.
1. A second split pulley 12 is provided on the output shaft 10, and a transmission belt 13 is wound around the first and second split pulleys 11 and 12. The first and second pulleys 11 and 12 are composed of a pulley portion 14 fixed to the input shaft 9 and the output shaft 10 by a spline structure, and a pulley portion 15 movable in the axial direction. The pulley portion 15 on the moving side of the pulley 12 is urged by the spring 16 toward the pulley portion 14 on the fixed side, and the pulley portion 15 on the moving side is fixed to the pulley on the fixed side in proportion to an increase in the load on the output shaft 10 side. The part 14 is provided with a cam mechanism 17 for pushing.

A ring member 18 is externally fitted to the moving pulley portion 15 of the first split pulley 11 via a bearing, and a pair of pins 18a fixed to the ring member 18 are provided on the case side recess of the continuously variable transmission 3. 19, the ring member 18 is prevented from rotating. As shown in FIGS. 3 and 2, a cylindrical cam member 20 (corresponding to a transmission portion) is externally fitted to the input shaft 9 via a bearing, and a linear bottom portion 2 is formed.
0a and a pair of concave portions formed of a pair of left and right symmetrical inclined surfaces 20b are formed in the cam member 20.
The roller 18b of the eighth pin 18a has entered the pair of recesses of the cam member 20.

In the state shown in FIGS. 2 and 3, the pulley portion 15 on the moving side of the first split pulley 11 is farthest to the left of the drawing from the pulley portion 14 on the fixed side, and the second pulley 12
The pulley portion 15 on the moving side is the pulley portion 1 on the fixed side.
This is the state of the lowest speed position closest to No. 4. When the cam member 20 is rotated right and left from this state, the inclined surface 20
b, the pulley portion 15 on the moving side of the ring member 18 and the first split pulley 11 is connected to the pulley portion 14 on the fixed side.
The pulling operation approaches the side, and the winding radius of the transmission belt 13 around the first split pulley 11 increases. Along with this, the pulley portion 15 on the moving side of the second pulley 12
However, the continuously variable transmission 3 is shifted to the high speed side from the fixed pulley portion 14 to the right in the drawing.

Next, the operation structure of the belt type continuously variable transmission 3 and the forward / reverse switching device will be described. 2 and 1
As shown in FIG. 2, a boss member 21 is fixed to an end of the cam member 20 outside the continuously variable transmission 3, and a sector gear 22 is fixed to the boss member 21. An electric motor 23 is fixed to a fixed portion of the body, and a reduction mechanism 24 using a flat gear is provided on the electric motor 23. A pinion gear 24 a of the reduction mechanism 24 is engaged with the sector gear 22. Boss member 2
1, a ring member 25 is externally fitted,
A gearshift lever 26 (corresponding to a gearshift operating tool) is supported by the gearshift lever.

Pin 25 of arm 25a of ring member 25
b enters the opening 22a of the sector gear 22, and a pair of rubber-like pressure-sensitive sensors 27 and 28 (corresponding to operation state detecting means) sandwich the pin 25b of the arm 25a. It is fixed to. A switching valve (not shown) for switching the forward / reverse switching device between the forward position, the reverse position, and the neutral stop position is provided, and the sector gear 22 and the switching valve are connected via the push-pull wire 29 and the accommodating mechanism 30. Are linked.

As shown in FIG. 5, a control device 31 (corresponding to control means) for operating the electric motor 23 is provided, and a motor driver 32 for supplying an operation current A1 and a holding current A2, which will be described later, to the electric motor 23. , And a controller 33 are provided in the control device 31. The controller 33 includes pulse signal output means 34 for outputting pulse signals P1 and P2 as shown in FIG. 8, and detection means 35 for detecting the value of the holding current A2 by feedback.

A vehicle speed sensor 3 for detecting the actual forward rotation speed V2 and the actual reverse rotation speed V2 of the crawler traveling device 6 shown in FIG.
The controller 33 receives signals from the vehicle speed sensor 39 and signals from the pressure-sensitive sensors 27 and 28. An operation position sensor 36 (corresponding to load detection means) for detecting the operation position of the shift lever 26 and a rotation speed sensor 37 (corresponding to load detection means) for detecting the rotation speed of the engine 1 are provided. The signal of the rotation speed sensor 37 is input to the controller 33.

In the combine, in the pair of left and right crawler traveling devices 6 shown in FIG. 4, a signal for slowly turning the side clutch (not shown) of one crawler traveling device 6 and applying a brake to one crawler traveling device 6 is provided. For example, ground turning or super turning that drives one crawler traveling device 6 in the reverse direction is performed. A steering lever (not shown) for performing the turning operation of the crawler traveling device 6 is provided, and a turning sensor 38 (corresponding to turning state detecting means) for detecting that the steering lever is operated is provided. The signal of the turning sensor 38 is input to the controller 33.

Next, the operation of the belt-type continuously variable transmission 3 and the forward / reverse switching device by the shift lever 26 will be described with reference to FIGS. If the shift lever 26 is operated from the neutral stop position N to a range on the forward side F,
When the forward / reverse switching device is operated to the forward position by the push-pull wire 29 and the switching valve, and when the shift lever 26 is operated from the neutral stop position N to the reverse side R, the push-pull wire 29 and the switching valve As a result, the forward / reverse switching device is operated to the reverse position.

When the shift lever 26 is operated to the forward side F (or the reverse side R), the pin 25b is pressed by the pressure sensor 27 (or the reverse side pressure sensor 28) of the forward side F (step S1). , S2), a signal is input to the controller 33 from the pressure sensor 27 on the forward side F (or the pressure sensor 28 on the reverse side). Thereby, the pulse signal P1 of the forward side F (or the reverse side R) as shown in FIG. 8 is output from the controller 33 to the motor driver 32, and the forward side F corresponding to the pulse signal P1 is output from the motor driver 32.
The (or reverse R) operation current A1 is output to the electric motor 23, and the electric motor 23 applies an assist force along the forward side F (or the reverse side R) to the shift lever 26 (steps S3 and S4). ).

As described above, when the shift lever 26 is operated to the forward side F in the range from the neutral stop position N to the forward side F, the assisting force is applied from the electric motor 23 to the forward side F, so that the continuously variable transmission is provided. 3 is operated to shift to the high-speed side, and the shift lever 26 is shifted to the reverse side R (the neutral stop position N side).
, The assisting force is applied from the electric motor 23 to the reverse R (the neutral stop position N side), and the continuously variable transmission 3
Is shifted to the low speed side. Conversely, when the shift lever 26 is operated to the reverse R in the range from the neutral stop position N to the reverse R, an assist force is applied to the reverse R from the electric motor 23, and the continuously variable transmission 3 shifts to the higher speed. The shift lever 26 is moved to the forward side F (the neutral stop position N
Side), an assist force is applied from the electric motor 23 to the forward side F (the neutral stop position N side), and the continuously variable transmission 3 is shifted to the low speed side. In this case, as shown in FIG. 8, in one cycle T, the ratio (T1 / T2) between the output time T1 of the pulse signal P1 and the stop time T2 is set to 1.0, so that the pulse signal P1 is continuous. Output state.

Next, it is assumed that the operation of the shift lever 26 to the forward side F (or the reverse side R) is stopped. In this case, since the signals of the pressure sensors 27 and 28 on the forward side F and the reverse side R are stopped (steps S1 and S2), the vehicle speed sensor 39 determines whether the vehicle is running or stopped (mainly). Whether the clutch (not shown) or the traveling clutch (not shown) is disengaged is detected (step S5).

When the vehicle is traveling when the operation of the shift lever 26 to the forward side F (or the reverse side R) is stopped, the shift lever 26 is moved to the high speed side (from the neutral stop position N to the forward side F). If the vehicle is operated to the position on the reverse side R (step S7), it is determined that the traveling load applied to the aircraft is large. Therefore, when the body is moving forward (when the shift lever 26 is operated in the range from the neutral stop position N to the forward side F), or when the body is moving backward (the shift lever 26).
Is operated in the range from the neutral stop position N to the reverse side R), the controller 33 sends the forward side F as shown in FIG.
(Or the reverse R) pulse signal P2 is
2 is output. In the pulse signal P2 on the forward side F (or the reverse side R), the ratio (T1 / T2) of the output time T1 and the stop time T2 in one cycle T is a sufficiently small value (for example, 0.1 to 0.2). ), The forward side F
The holding current A2 (or sufficiently smaller than the above-described operation current A1) of the predetermined value B (or the reverse side R) is the motor driver 32.
Is output to the electric motor 23 (steps S9 and S1).
0, S11).

The belt-type continuously variable transmission 3 shown in FIG.
Since it is going to return to the neutral stop position N side by the tension of the transmission belt 13, a small assist force on the forward side F (or the reverse side R) of the electric motor 23 and the above-mentioned neutral stop position N side of the continuously variable transmission 3. The transmission lever 26 and the continuously variable transmission 3 are held at their operation positions (transmission positions) in balance with the return biasing force.

In this case, what value of the holding current A2 on the forward side F (or the reverse side R) is supplied to the electric motor 23 to determine whether the shift lever 26 and the continuously variable transmission 3 are held is determined by an experiment. The value of the holding current A2 on the forward side F (or the reverse side R) is a predetermined value B. Of the holding current A2 on the forward side F (or the reverse side R) supplied from the motor driver 32 to the electric motor 23,
As shown in FIG. 8, only the value of the holding current A2 in the small range C including the predetermined value B (the value of the holding current A out of the small range C is ignored) is fed back from the motor driver 32 to the controller 33. And the ratio (T1) between the output time T1 and the stop time T2 in the pulse signal P2 such that the holding current A2 on the forward side F (or the reverse side R) is maintained at the predetermined value B. / T2) is automatically changed by the controller 33.

Next, when the body is running when the operation of the shift lever 26 to the forward side F (or the reverse side R) is stopped, the steering lever is operated and the body is in a turning state. (Step S6), it is determined that the traveling load applied to the body is large, and the forward side F (or the reverse side R) is determined as described above.
Is supplied to the electric motor 23, and the shift lever 26 and the continuously variable transmission 3 are held at their operation positions (shift positions) (Steps S13, S14, S1).
5).

In this case, a timer (not shown) starts counting (step S12), and if the turning state of the body continues for a set time T3 (steps S16 and S16).
17), the holding current A2 on the forward side F (or the reverse side R) is stopped only for a predetermined time T4 (corresponding to an auxiliary restraint means)
(Step S18). Accordingly, during the predetermined time T4, the continuously variable transmission 3 is automatically shifted to the low speed side (the neutral stop position N side) by the traveling load, and accordingly, the shift lever 26 is moved to the low speed side (the neutral position). (The stop position N side). When the predetermined time T4 has elapsed, the holding current A2 on the forward side F (or the reverse side R) is again supplied to the electric motor 23, and the shift lever 26 and the continuously variable transmission 3 are held at their operation positions (shift positions). (Step S1
9, S20, S21), when the steering lever is operated to the neutral position and the body returns to the straight traveling state, the process proceeds to step S7 (step S22).

Next, when the operation of the shift lever 26 to the forward side F (or the reverse side R) is stopped, the machine is stopped (the main clutch (not shown) or the traveling clutch (not shown)). If the cutting operation is performed), the supply of the operation current A1 and the holding current A2 to the electric motor 23 as described above is stopped (steps S5 and S8). Transmission lever 26
If the steering lever is not operated and the shift lever 26 is not operated to the high speed side even when the aircraft is running when the operation to the forward side F (or the reverse side R) is stopped (the In a state where the vehicle is traveling straight at a low speed, (steps S5, S6, S
7), it is determined that the running load applied to the body is small, and the supply of the operating current A1 and the holding current A2 to the electric motor 23 as described above is stopped (corresponding to a check means) (step S8). In such a case where the aircraft stops or the aircraft is traveling straight at a low speed, it is unnecessary to use the electric motor 23.
By not supplying the operation current A1 and the holding current A2 to the power supply, power can be saved and durability can be prevented from being reduced due to heating of the electric motor 23.

[Other Embodiments of the Invention] The operation of the belt-type continuously variable transmission 3 and the forward / reverse switching device by the shift lever 26 may be replaced with that shown in FIG. 9 instead of FIGS. As shown in FIG. 9, when the shift lever 26 starts to be operated to the forward side F (or the reverse side R) (step S3).
1, S32), as in the case of FIG. 6, the electric motor 23 applies an assist force along the forward side F (or the reverse side R) to the shift lever 26 (steps S33, S3).
4).

Next, when the operation of the shift lever 26 to the forward side F (or the reverse side R) is stopped and the vehicle is running (step S35), the rotation speed of the engine 1 is detected by the rotation speed sensor 37. The crawler traveling device 6 is detected based on the operation position of the shift lever 26 (the shift position of the continuously variable transmission 3) detected by the operation position sensor 36 (step S36) and the rotation speed of the engine 1 described above. Is calculated (step S37). At the same time, the actual rotation speed V2 of the forward (or backward) rotation of the crawler traveling device 6 is detected by the vehicle speed sensor 39 (step S38).

Thus, the slip ratio of the continuously variable transmission 3 is obtained from the difference between the calculated rotation speed V1 of the crawler traveling device 6 and the actual rotation speed V2. 3 (slip ratio of 3) or more (step S39), it is determined that the traveling load applied to the body is large, and the forward side F (or the reverse side R) is held as in the case of FIGS. The current A2 is supplied to the electric motor 23, and the shift lever 26 and the continuously variable transmission 3 are held at their operation positions (shift positions) (Step S40,
S41, S42).

Conversely, when the operation of the shift lever 26 toward the forward side F (or the reverse side R) is stopped, the machine is stopped (the main clutch (not shown) or the traveling clutch (not shown)).
Is turned off), the supply of the operating current A1 and the holding current A2 to the electric motor 23 as described above is stopped (steps S35 and S43). The difference between the calculated rotation speed V1 of the crawler traveling device 6 and the actual rotation speed V2 (even if the body is running when the operation of the shift lever 26 to the forward side F (or the reverse side R) is stopped) If the slip ratio of the continuously variable transmission 3 is less than the set value V3 (step S3)
9) It is determined that the running load applied to the body is small, and the supply of the operation current A1 and the holding current A2 to the electric motor 23 as described above is stopped (corresponding to a check means) (step S43).

In FIG. 9, the magnitude of the traveling load applied to the body is determined by the difference between the actual rotational speed V2 and the rotational speed V1 of the crawler traveling device 6 calculated based on the detected rotational speed of the engine 1. I try to judge,
Instead, the rotational speed at no load at the current accelerator position of the engine 1 is obtained in advance, and the difference between the rotational speed at no load and the actual rotational speed detected by the rotational speed sensor 37 is calculated as follows. The magnitude of the traveling load may be determined.

[0037]

According to the first aspect of the present invention, the continuously variable transmission returns to the low speed side without the worm speed reduction mechanism in the traveling speed change structure of the working vehicle having the electric motor for applying the assist force to the speed change operation tool. By configuring the existing electric motor to provide a holding current that resists trying to
The speed change operation of the continuously variable transmission can be performed by quickly operating the speed change operation tool, thereby improving operability. As with the case where the worm speed reduction mechanism is equipped, there is no special friction holding mechanism that holds the speed change operation tool and the continuously variable transmission at an arbitrary shift position. Since the motor is also used for holding the speed change operation tool and the continuously variable transmission at any operation position (speed change position), it is advantageous in terms of simplification of the structure. When unnecessary, such as when the running load is small, the continuously variable transmission is held at an arbitrary shift position by the mechanical resistance of the electric motor or the like without supplying the holding current to the electric motor. With such a configuration, power can be saved and durability can be prevented from lowering due to heating of the electric motor.

According to the features of claim 2, the "effect of the invention" of claim 1 is provided as in the case of claim 1. Since the traveling load applied to the body can be easily detected by detecting the operation position of the speed change operation tool as in the feature of the second aspect, it is only necessary to provide an operation position sensor for detecting the operation position of the speed change operation tool. This is advantageous in terms of simplification of the structure.

According to the feature of the third aspect, the "effect of the invention" of the first aspect is provided similarly to the case of the first aspect. Since the running load applied to the fuselage can be easily detected by detecting the number of revolutions of the engine as in the feature of the third aspect, it is only necessary to provide a number of revolutions sensor for detecting the number of revolutions of the engine. This is advantageous in terms of chemical conversion. Further, since the running load applied to the body and the engine speed are directly related, the running load applied to the body can be detected with high accuracy by detecting the engine speed.

According to the feature of claim 4, claim 1 or 2
Similarly to the case of the third or third aspect, the present invention has the “effect of the invention” of the first or second or third aspect. According to the feature of claim 4, the continuously variable transmission is automatically shifted to a lower speed side when the body is continuously turned, so that the stop of the engine is avoided beforehand. The running performance and turning performance were able to be improved.

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.

[Brief description of the drawings]

FIG. 1 is a side view of the vicinity of a continuously variable transmission, a shift lever, and an electric motor.

FIG. 2 is a longitudinal rear view of the continuously variable transmission.

FIG. 3 is a plan view of a cam member for gear shifting operation in the continuously variable transmission.

FIG. 4 is a schematic diagram showing a transmission system of the combine.

FIG. 5 is a diagram showing a control system of the electric motor.

FIG. 6 is a diagram showing a flow of a first half of control at the time of a shift operation by a shift lever.

FIG. 7 is a diagram showing a flow of the latter half of control at the time of a shift operation by a shift lever.

FIG. 8 is a diagram illustrating states of a pulse signal output to a motor driver, an operation current supplied to the electric motor, and a holding current.

FIG. 9 is a diagram showing a control flow at the time of a shift operation by a shift lever in another embodiment of the invention.

[Explanation of symbols]

DESCRIPTION OF REFERENCE NUMERALS 1 engine 3 traveling continuously variable transmission, belt-type continuously variable transmission 20 traveling continuously variable transmission transmission 23 electric motor 26 transmission operation tool 27, 28 operating state detecting means 31 control means 36, 37 load Detecting means 38 Turning state detecting means A1 Operating current A2 Holding current T3 Set time

────────────────────────────────────────────────── ─── Continuation of the front page (72) Mineyoshi Motomura 64, Ishizukitamachi, Sakai-shi, Osaka Kubota Sakai Works Co., Ltd. (56) References JP-A-5-60231 (JP, A) JP-A-3 −149455 (JP, A) Japanese Utility Model Hei 6-6819 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 61/16-61/36 F16H 63/00-63/38

Claims (5)

(57) [Claims] 1. A speed change device (26) which is artificially operated in a forward / reverse direction and a speed change portion (2) of a continuously variable transmission (3) for traveling.
0) is mechanically interlocked and connected so that the power of the electric motor (23) is applied as an assist force in the forward and reverse directions along the operation direction of the speed change operation tool (26). 26) is provided with operation state detecting means (27), (28) for detecting whether or not the operation is artificially performed and the operation direction, and when the shift operation tool (26) is artificially operated,
An operation current (A) is applied to the electric motor (23) so that an assist force is applied in the operation direction of the speed change operation tool (26).
1) A traveling speed change structure of a working vehicle provided with a control means (31) for supplying 1), wherein the speed change operation tool (26) is artificially operated by the operation state detection means (27) and (28). When it is detected that there is no gear, the continuously variable transmission (3) is prevented from returning to the low speed side, and the continuously variable transmission (3) is held at the shift position so that the continuously variable transmission (3) is held. Motor (2
The control means (31) is configured to supply the holding current (A2) to the load detection means (3) for detecting the running load applied to the body.
6) and (37), wherein the load detecting means (36),
(37) A traveling speed change structure of a working vehicle including a restraint means for preventing a hold current (A2) from being supplied to the electric motor (23) when a travel load is small based on the detection of (37). 2. The traveling speed change structure of a work vehicle according to claim 1, wherein said load detection means (36) is configured to detect a traveling load based on an operation position of said speed change operation tool (26). 3. The traveling speed change structure of a work vehicle according to claim 1, wherein said load detecting means (37) is configured to detect a traveling load based on a rotation speed of an engine (1). 4. A turning state detecting means (38) for detecting whether or not the body is in a turning state, and the turning state of the body is set for a set time (T3) based on the detection of the turning state detecting means (38). 4. The method according to claim 1, further comprising an auxiliary check means for preventing the holding current (A2) from being supplied to the electric motor (23). 3. The traveling speed change structure of a working vehicle according to claim 1. 5. The traveling speed change of a working vehicle according to claim 1, wherein the traveling continuously variable transmission (3) is a belt-type continuously variable transmission (3). Construction.