JP2010208446A - Working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a working machine equipped with a continuously variable transmission mechanism capable of attaining cost reduction and high controllability. <P>SOLUTION: A rice transplanter 1 includes an engine 2, a motor 22, a HST 35, two rear wheels 21, a differential apparatus 23 and a controller. The HST 35 changes the output of the engine 2. The differential apparatus 23 outputs differential power between the output of the HST 35 and the output of the motor 22 to the rear wheels 21. The controller controls the rotational speed of the motor 22. Besides, the output of the engine 2 is kept substantially constant. Further, the controller drives the rotation of the motor 22 only in such a direction as to cancel a driving force of the HST 35. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a work machine. In detail, it is related with the continuously variable transmission mechanism with which a working machine is provided.

  In a working machine such as a rice transplanter or a tractor, it is preferable that the engine output can be changed continuously in order to run smoothly in the field. In particular, a rice transplanter is required to smoothly perform zero starting (starting from a stopped state) when crossing a ridge in order to prevent the mounted seedling mat from collapsing.

  As a working machine that satisfies such a demand, a working machine that includes an HMT (hydraulic-mechanical transmission) as a transmission is known. The HMT includes a planetary gear type differential and an HST (hydrostatic continuously variable transmission). The engine output is input to the differential and the HST. The output from the HST is input to the differential device, and is combined with the engine output and transmitted to the wheels. That is, the differential power between the direct output from the engine and the output of the engine shifted by the HST is taken out by the differential device to drive the wheels. Since the HST can be continuously variable, the output of the engine can be continuously variable by the above-described configuration.

  Specifically, the rotation of the engine can be decelerated by setting the rotation speed of the HST so that the output of the engine is canceled by the output of the HST. Further, when the rotation of the HST is stopped, the vehicle body can be efficiently driven only by the rotational driving force of the engine. As described above, by driving the wheels with the differential power between the engine output and the HST output, it is possible to change the travel speed steplessly from low speed travel to high speed travel.

  On the other hand, Patent Document 1 discloses a work vehicle that includes an electric motor and a planetary gear type differential device, and the differential power of the engine and the electric motor is extracted by the differential device and supplied to the traveling device. . In Patent Document 1, it is assumed that continuously variable transmission can be realized easily and at low cost by using an engine and a motor together.

JP 2005-199755 A

  By the way, in the structure provided with said HMT, since HST had to be always driven except at the time of high speed driving | running | working, there existed a problem that the load of an engine was heavy and the size of the engine had to be enlarged. Further, in the configuration provided with the above HMT, there is no neutral range of the transmission, and it is necessary to completely cancel the rotation of the engine by the rotation of the HST in order to completely stop the vehicle body. However, since the HST uses hydraulic pressure, fine adjustment is difficult, and the vehicle body cannot be completely stopped, and creep (the vehicle body travels at a low speed when stopped) may occur.

  On the other hand, in the above-mentioned patent document 1, since the engine output is canceled by the motor and the speed is changed, a large motor is required to enable complete stopping of the vehicle body, which leads to an increase in cost. It is done.

  In addition, in a four-wheel drive work machine such as a rice transplanter or tractor, the vehicle body is turned by changing the angle of the front wheel. It is necessary to make arrangements. In order to smoothly perform such a sudden turn, conventionally, in a working machine having wheels on the left and right sides of the vehicle body (for example, a rice transplanter or a tractor), power transmission to the rear wheel on the inner ring side can be cut by a clutch. It was configured as follows. However, in such a configuration, it is difficult to arbitrarily adjust the rotation speed of the rear wheel on the inner ring side, so that it is not possible to smoothly perform a turning operation other than a sharp turn, and it may also cause the field to be damaged. Can be.

  The present invention has been made in view of the above circumstances, and a main object of the invention is to provide a work machine including a continuously variable transmission mechanism that is inexpensive and excellent in controllability.

Means and effects for solving the problems

  The problems to be solved by the present invention are as described above. Next, means for solving the problems and the effects thereof will be described.

  According to the viewpoint of this invention, the working machine of the following structures is provided. That is, this working machine includes an engine, an electric motor, a continuously variable transmission, a plurality of wheels, a differential device, and a control unit. The continuously variable transmission shifts the output of the engine. The differential device outputs differential power between the output of the continuously variable transmission and the output of the electric motor to the wheels. The control unit controls the rotation speed of the electric motor. The output of the engine is substantially constant. And the said control part rotationally drives the said electric motor only in the direction which cancels the driving force of the said continuously variable transmission.

  Thus, the continuously variable transmission and the electric motor can be used in combination to shift the output of the engine and transmit it to the wheels. Therefore, since the speed is reduced in two steps, such as the engine is decelerated by the continuously variable transmission and then decelerated by the electric motor, a small motor can be used, and the cost can be reduced. it can. In addition, since the electric motor is rotationally driven only in the direction to cancel the driving force of the continuously variable transmission, a smaller motor can be used compared to a configuration in which the vehicle body is actively moved by the driving force of the motor. Cost can be reduced.

  The working machine is preferably configured as follows. That is, the wheels are arranged to correspond to the left and right sides of the vehicle body. The electric motor is provided on each of the left and right sides of the vehicle body corresponding to the wheels. The differential device is provided on each of the left and right sides of the vehicle body corresponding to the electric motor.

  Thereby, since the electric motor is provided corresponding to each of the left and right wheels, it is possible to control each wheel individually according to the situation, and the traveling performance of the work implement can be improved. Also, by shifting with the left and right electric motors, the traveling performance required for the work implement is ensured with a low-torque, inexpensive motor compared to when shifting both the left and right wheels with a single electric motor. be able to.

  The working machine is preferably configured as follows. That is, this working machine includes a steering operation tool and a transmission operation tool. The transmission ratio of the continuously variable transmission is changed according to the operation amount of the transmission operation tool. In addition, the control unit performs control so as to increase the rotation speed of the electric motor on the corresponding side as the operation amount from the neutral position of the steering operation tool increases.

  As a result, when the vehicle body turns, the corresponding wheel can be decelerated by increasing the speed of the electric motor, so that the turning performance is improved and a smooth turning operation is possible. Further, the speed when traveling straight can be changed by changing the gear ratio of the continuously variable transmission. That is, it is possible to use a small electric motor by configuring so as not to perform a shift by the electric motor when going straight.

  The working machine is preferably configured as follows. That is, when the steering operation tool is operated while the vehicle body is traveling at a speed equal to or higher than a predetermined speed, the control unit increases the reduction ratio of the continuously variable transmission. At the same time, the control unit controls the rotational speed of the corresponding electric motor to increase as the operation amount from the neutral position of the steering operation tool increases.

  As a result, the speed of the vehicle body can be reduced by the continuously variable transmission when a turning operation is performed while traveling at a high speed, so that the turning operation can be safely performed while preventing the turning operation from being performed at a high speed. be able to. Further, since the corresponding wheel is decelerated by the electric motor after being decelerated by the continuously variable transmission, the effect of improving the turning performance of the work implement can be exhibited even with a small motor.

  The working machine is preferably configured as follows. That is, this working machine includes a torque detector that detects the torque of the electric motor. When the torque of the electric motor decreases, the control unit increases the rotational speed of the electric motor and increases the reduction ratio of the continuously variable transmission.

  That is, since the electric motor is excellent in responsiveness, accurate traction control is possible. Therefore, by configuring as described above, when a slip occurs on the wheel, it is possible to accurately control the wheel to decelerate and recover from the slip. Further, by using together with the control for decelerating the vehicle speed by the continuously variable transmission when a slip occurs, it is possible to appropriately prevent the wheels from idling even with a small motor.

  The working machine is preferably configured as follows. That is, the differential device is a planetary gear type differential device. One of the continuously variable transmission, the electric motor, and the wheel is connected to each of the sun gear, the planetary carrier, and the ring gear included in the differential device.

  Thereby, the difference of the output of a continuously variable transmission and an electric motor can be output to a traveling apparatus.

The right view which shows the basic composition of the rice transplanter which concerns on one Embodiment of this invention. The schematic skeleton figure which shows the driving force transmission mechanism of a rice transplanter. The block diagram which shows the functional structure of a rice transplanter. The figure which shows the relationship between the operation amount of a steering handle, and HST vehicle speed.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a right side view showing a basic configuration of a rice transplanter according to the present embodiment.

  As shown in FIG. 1, a rice transplanter 1 as a working machine of the present embodiment includes an engine 2, a driver seat 3, an operation unit 4, a front wheel 20, a rear wheel 21, a planting unit 6, The vehicle body is provided with.

  The engine 2 is configured as a general gasoline engine, but may be configured as a diesel engine, for example. A driving force is taken out from the engine 2 by a PTO shaft (power take-off shaft) (not shown), shifted by a planting transmission unit (not shown), and then transmitted to the planting unit 6. Can be driven. Further, the driving force from the engine 2 is transmitted to the wheels 20 and 21 via a driving force transmission mechanism described later, whereby the vehicle body of the rice transplanter 1 can be caused to travel.

  The planting unit 6 includes a seedling platform 7 that can slide back and forth in the left and right directions, and a planting mechanism that includes a planting claw 8 that can be moved up and down. The planting unit 6 places a seedling mat on the seedling stand 7 and the rice transplanter 1 travels in the field, so that the planting operation of continuously planting seedlings one by one from the seedling mat with the planting claws 8 is performed. It can be performed automatically.

  A front wheel 20 and a rear wheel 21 as a traveling device are provided in pairs on the left and right sides of the vehicle body (therefore, the rice transplanter 1 has a total of four wheels). Moreover, the rice transplanter 1 is a four-wheel drive type, and is configured such that the driving force is transmitted to each wheel.

  The operation unit 4 includes a steering handle 10, an accelerator lever 11, and a transmission lever 12.

  The steering handle 10 is configured as a steering wheel type steering operation tool, and is configured to be able to rotate left and right. The operator of the rice transplanter 1 can turn the rice transplanter 1 by changing the turning angle of the front wheel 20 by rotating the steering handle 10.

  The accelerator lever 11 is configured to be pivotable back and forth, and is configured to be able to change the rotational speed of the engine 2 in accordance with the amount of rotation of the accelerator lever 11. Thereby, for example, when not working, the engine 2 is rotated at a low speed, thereby reducing noise and fuel consumption. During the work, in order to rotate the engine 2 at a rated speed at which the planting unit 6 can be driven stably, the position of the accelerator lever 11 is fixed at the position of the rated speed. Therefore, an operation for changing the traveling speed of the vehicle body is performed by the speed change lever 12.

  The transmission lever (transmission operation tool) 12 is configured to be able to rotate forward and backward, and is configured to be able to change the traveling speed of the vehicle body according to the amount of rotation of the transmission lever 12. For example, when the shift lever 12 is rotated to the farthest when viewed from the operator, the rice transplanter 1 travels at the highest speed, and when the shift lever 12 is rotated to the neutral position, the travel of the rice transplanter 1 stops. The shift lever 12 is configured so that the operation position can be adjusted steplessly, and the operator of the rice transplanter 1 adjusts the traveling speed of the rice transplanter 1 steplessly by adjusting the amount of rotation of the shift lever 12. be able to.

  Next, a configuration for shifting the driving force from the engine 2 and transmitting it to each wheel will be described with reference to FIG. FIG. 2 is a schematic skeleton diagram showing the driving force transmission mechanism of the rice transplanter 1. FIG. 2 is a simplified diagram showing only the main part of the driving force transmission mechanism, and there are cases where gears, pulleys, and the like unnecessary for the description of the driving force transmission mechanism are omitted. Further, the PTO shaft that outputs the driving force to the planting unit 6, the planting transmission unit, and the like are omitted. In the following description, when there is a configuration corresponding to the left and right sides of the vehicle body, L (left side) or R (right side) is added to the end of the reference numeral of the configuration to indicate left and right distinction. Further, when there is no particular need to indicate the left and right, the description will be made without adding L or R to the reference numerals.

  As shown in FIG. 2, the rice transplanter 1 includes two electric motors 22, a generator (generator) 24, and an HST (hydrostatic continuously variable transmission) 35. Each electric motor 22 is provided as a pair on the left and right sides of the vehicle body, and can be rotated by receiving electric power from a battery (not shown). On the other hand, the generator 24 is connected to the rotating shaft of the engine 2 and is configured to generate electricity by the rotation of the rotating shaft and charge the battery.

  The output from the engine 2 is input to the HST 35 via the engine output shaft 30. The HST 35 includes a hydraulic pump 36 configured as a movable swash plate type axial piston pump, and a hydraulic motor 37 configured as a fixed swash plate type axial piston motor. The hydraulic pump 36 and the hydraulic motor 37 are hydraulically operated. It is the structure connected by the circuit. Since the configuration in which the input is steplessly shifted by the HST 35 and output is well known, detailed description thereof will be omitted, but the HST 35 drives the hydraulic pump 36 by the engine output shaft 30 and the HST output shaft by the hydraulic motor 37. It is comprised so that 38 may be rotationally driven.

  The movable swash plate has a trunnion shaft (not shown) as a swing shaft, and the inclination angle thereof can be changed steplessly. By changing the inclination angle, the discharge amount of the pressure oil from the hydraulic pump 36 is changed, and the rotational driving force taken out from the hydraulic motor 37 can be changed. Further, the inclination angle of the movable swash plate is configured to be changed in conjunction with the operation amount (rotation amount) of the speed change lever 12. With the above configuration, when the operator rotates the shift lever 12, the output of the engine 2 can be steplessly shifted by the HST 35 and output from the HST output shaft 38.

  Further, as shown in FIG. 2, a differential device 23 is provided between the driving force transmission paths from the HST 35 to the rear wheel 21. The differential device 23 is a planetary gear type differential gear, and has a known configuration including a sun gear 25, a planetary carrier 27 that rotatably supports the planetary gear 26, and a ring gear 28. The differential device 23 is provided so as to be paired on the left and right sides of the vehicle body. The left differential device 23L has a left rear wheel 21L and a left electric motor 22L, and the right differential device 23R has a right rear. The wheel 21R and the right electric motor 22R are connected to each other. In the differential device 23, the output of the HST 35 and the output of the electric motor 22 are combined, and the combined driving force is transmitted to the rear wheel 21.

  Specifically, it is as follows. In other words, the output of the HST 35 output from the HST output shaft 38 is input to the planetary carrier 27 via a plurality of gears and shafts, and the planetary carrier 27 is rotationally driven. When the planetary carrier 27 is rotationally driven, the planetary gear 26 circulates around the sun gear 25. On the other hand, the driving force from the electric motor 22 is input to the sun gear 25 via the motor output shaft 33 and rotationally drives the sun gear 25. Then, the driving force is transmitted from the planetary gear 26 to the ring gear 28, and the ring gear 28 rotates. An axle 34 is connected to the rotating shaft of the ring gear 28, and the axle 34 is connected to the rear wheel 21.

  With the above configuration, the differential power between the rotational driving force from the HST 35 and the rotational driving force from the electric motor 22 is taken out by the differential device 23, and this differential power is output to the axle 34. For example, when the rotation of the electric motor 22 is stopped, the driving force from the HST 35 is output to the axle 34 without being affected by the deceleration by the electric motor 22. On the other hand, when the electric motor 22 rotates in a direction that cancels the rotation of the HST 35, the rotation of the HST 35 is decelerated by the rotation of the electric motor 22 and is output to the axle 34.

  As described above, the rice transplanter 1 according to the present embodiment is configured to change the vehicle speed by using the HST 35 and the electric motor 22 together. Therefore, by using the electric motor 22 that is excellent in controllability, it is possible to realize accurate and quick shift control that was difficult with only the HST 35 shift. In addition, by using HST 35 in combination, a smaller motor can be used as compared with the case where shifting is performed by only the electric motor 22.

  The HST 35 is usually provided with a dead zone near the neutral position, and the rotation of the hydraulic motor 37 can be completely stopped by positioning the movable swash plate in the dead zone. Therefore, the vehicle body can be reliably stopped without generating creep unlike HMT. In addition, since the HST 35 is used, it is possible to smoothly perform zero start.

  Further, in the configuration using the conventional HMT, it is necessary to cancel the driving of the engine by the HST at the time of stopping, and the engine load is large. In this respect, according to the configuration of the present embodiment, the driving angle of the hydraulic motor 37 may be stopped by setting the inclination angle of the movable swash plate to zero at the time of stopping, so that the load on the engine 2 is small, which can contribute to the improvement of fuel consumption.

  Next, in the rice transplanter 1 of this embodiment, the structure for controlling the rotational speed of a wheel with the electric motor 22 is demonstrated. FIG. 3 is a block diagram showing a functional configuration of the rice transplanter 1. In the figure, solid arrows indicate electrical connections, and dotted arrows indicate mechanical connections. In order to simplify the illustration in FIG. 3, the differential device 23, the rear wheel 21, the axle sensor 51, the torque detection unit 54, and the like are illustrated one by one, but these are actually illustrated in FIG. 2. As shown in FIG.

  As shown in FIG. 3, the rice transplanter 1 includes a control unit 40, a slip rate estimation unit 43, and a handle sensor 53.

  The control unit 40 and the slip rate estimation unit 43 are configured as, for example, a microprocessor. The control unit 40 and the like are configured to control the HST 35 and the electric motor 22 in cooperation with hardware such as CPU, ROM, and RAM and software.

  The handle sensor 53 is configured to detect an operation amount (handle turning angle) of the steering handle 10 and transmit the detected value to the control unit 40. The control unit 40 can detect the operation amount of the steering handle 10 by receiving a signal from the handle sensor 53. In the following, for the convenience of explanation, the operation amount of the steering handle 10 is expressed as a numerical value in percent (%). Specifically, the amount of operation when the steering handle 10 is rotated to the maximum left and right is 100%, and the amount of operation when the steering handle 10 is in the neutral position (straight forward position) is 0%.

  Then, the control unit 40 controls the rotation of the electric motor 22 so as to decelerate the rear wheel 21 on the side corresponding to the turning direction in accordance with the operation amount of the steering handle 10. That is, when the steering handle 10 is rotated and the vehicle body starts to turn, the rear wheel 21 on the corresponding side (inner wheel side) is decelerated to realize smooth turning.

More specifically, the control unit 40 rotates the inner ring-side electric motor 22 at a rotation speed proportional to the operation amount of the steering handle 10 detected by the handle sensor 53, and cancels the rotation of the HST 35, thereby The rear wheel 21 is decelerated. The number of rotations (motor instruction number of rotations) that the control unit 40 instructs to the electric motor 22 at the time of turning is obtained by the following equation.
Motor command rotation speed (min ⁻¹ ) = HST rotation speed × turning deceleration gear ratio ÷ straight drive gear ratio × steering handle operation amount (%) / 100
Here, the turning-side gear ratio indicates a ratio between the input rotational speed from the electric motor 22 and the output rotational speed to the axle 34 when the differential carrier 23 is considered with the planetary carrier 27 fixed. Further, the straight gear ratio indicates the ratio of the input rotation speed from the HST 35 and the output rotation speed to the axle 34 when the differential gear 23 is considered with the sun gear 25 fixed.

As is apparent from the above equation, when the steering wheel operation amount is 0% (that is, when traveling straight), the motor instruction rotational speed is 0 (min ⁻¹ ), and the electric motor 22 is not rotationally driven. In other words, in the present embodiment, the control unit 40 changes the vehicle speed only by the HST 35 and does not perform a shift by the electric motor 22 when traveling straight.

  That is, if the electric motor 22 is to be shifted straightly, a large torque is required, so that a large motor is required and the cost is increased. In this regard, in the present embodiment, as described above, the gear shift during straight travel is performed only by the HST 35, so that the small electric motor 22 can be used, and the cost increase can be suppressed.

On the other hand, when the steering handle is operated left and right, the control unit 40 drives the electric motor 22 on the inner ring side at a rotational speed proportional to the operation amount of the steering handle. At this time, the control unit 40 rotates the electric motor 22 in a direction that cancels (decelerates) the rotation of the HST 35. Thereby, the rear wheel 21 on the inner ring side can be decelerated and the turning performance can be improved. For example, when the operator turns the steering handle 10 to the right, by rotating the right electric motor 22R at a rotational speed proportional to the operation amount of the steering handle 10, the HST 35 rotates in the right differential 23R. The speed is reduced by the rotation of the electric motor 22R, and the rotation speed of the right rear wheel 21R is reduced. Further, as can be seen from the above formula, when the turning angle of the handle is 100%, the electric motor 22 is rotated at a rotation speed capable of completely canceling the rotation of the HST 35. Thereby, the rotation of the rear wheel 21 on the inner ring side can be stopped and a sharp turn can be performed. In addition, the turning vehicle speed (wheel peripheral speed) of the inner ring can be obtained by the following equation.
Inner wheel turning vehicle speed (mm / sec) = vehicle speed calculated from shift lever position−motor vehicle speed calculated from motor commanded rotation speed Here, “vehicle speed calculated from shift lever position” means the rotation speed of engine 2 And the amount of operation of the shift lever 12 and the vehicle speed when the rice transplanter 1 goes straight. The “motor vehicle speed” indicates how much the vehicle speed is decelerated when the electric motor 22 is rotated at the motor instruction rotational speed.

  As described above, in the rice transplanter 1 according to the present embodiment, since the inner wheel is decelerated according to the operation amount of the steering handle 10, a smooth turn can be performed. Further, since the electric motor 22 is not used when going straight, the battery can be charged when going straight, and energy can be used efficiently such that the electric motor 22 uses current when turning.

  Further, as described above, in the present embodiment, the driving force of the electric motor 22 is used only in the direction in which the rotation of the HST 35 is decelerated. That is, if the electric motor 22 is to be rotated in a direction to further increase the rotation of the engine 2, a large torque is required because the electric motor 22 must bear a part of the running resistance of the vehicle body. The electric motor 22 will be enlarged. In this regard, by configuring as in the present embodiment, the electric motor 22 can be reduced in size and the cost can be reduced.

  Incidentally, since the electric motor 22 has a limitation on the number of rotations, the motor vehicle speed has an upper limit. Accordingly, when the rice transplanter 1 is traveling at a vehicle speed that is equal to or higher than the vehicle speed corresponding to the upper limit of the motor vehicle speed (limit motor vehicle speed), the rotation of the HST 35 may not be completely canceled by the rotation of the electric motor 22. When the steering handle 10 is greatly operated during such high speed traveling, the rear wheel 21 cannot be decelerated to a predetermined rotational speed, and smooth turning cannot be performed. In particular, even if the operation amount of the steering handle 10 is set to 100%, it becomes impossible to completely stop the rear wheel 21 on the inner ring side, so that it is difficult to make a sudden turn. Considering this point, the present embodiment is configured to increase the reduction ratio of the HST 35 when a turning operation is performed during high-speed traveling. Specifically, it is as follows.

  As shown in FIG. 3, the rice transplanter 1 of this embodiment includes a trunnion operation motor 31. The trunnion operation motor 31 is connected to a trunnion shaft (not shown) of a movable swash plate included in the HST 35. With this configuration, by driving the trunnion operation motor 31, the inclination angle of the movable swash plate of the hydraulic pump 36 can be changed, and the vehicle speed can be changed by changing the reduction ratio of the HST 35. The operation of the trunnion operation motor 31 is controlled by the control unit 40.

  FIG. 4 is a diagram showing the relationship between the operation amount of the steering handle 10 and the HST vehicle speed. The vertical axis in the figure is the HST vehicle speed, and the horizontal axis is the operation amount of the steering handle 10. Here, the HST vehicle speed is a vehicle speed before being decelerated by the electric motor 22 (that is, a vehicle speed when going straight). The HST vehicle speed is determined by the number of revolutions of the engine 2 and the amount of rotation of the speed change lever 12 operated by the operator, and can be changed by the control unit 40 driving the trunnion operation motor 31. The control unit 40 drives the trunnion operation motor 31 according to the operation amount of the steering handle 10 to reduce the HST vehicle speed when the vehicle body is traveling at a vehicle speed equal to or higher than the limit motor vehicle speed. It is configured.

  FIG. 4 shows a state where the HST vehicle speed is set to α by the shift lever 12. As shown in the figure, when the operation amount of the steering handle 10 is 0% (straight forward), the HST vehicle speed is a value α set by the speed change lever 12. In addition, since the wheel is not decelerated by the electric motor 22 when traveling straight, the rice transplanter 1 travels at the vehicle speed α.

On the other hand, when the steering handle 10 is rotated to the left or right, the trunnion operation motor 31 is driven according to the operation amount, and the HST vehicle speed is decelerated from α. In the figure, the limit motor vehicle speed is A, and the difference between the limit motor vehicle speed A and the HST vehicle speed after deceleration by driving the trunnion operation motor 31 is β. In this case, β when the handle is operated to a (%) is
β = (α−A) (1−a / 100)
Can be obtained. The deceleration rate of the HST 35 by driving the trunnion operation motor 31 is
Deceleration rate = (β + A) / α
Can be obtained. The controller 40 drives the trunnion operation motor 31 to decelerate the HST 35 so that the HST vehicle speed becomes the deceleration rate.

The turning vehicle speed when traveling at a speed higher than the limit motor speed is
The inner wheel turning vehicle speed (mm / sec) = the vehicle speed calculated from the shift lever position × the deceleration rate−the motor vehicle speed calculated from the motor command rotational speed.

  As can be seen from FIG. 4, β = 0 when the operation amount of the steering handle 10 is 100%. That is, even when the vehicle is traveling at a speed higher than the limit motor vehicle speed, when the steering handle 10 is operated to 100%, the HST vehicle speed is reduced to the limit motor vehicle speed by the trunnion operation motor 31. Thereby, even during high-speed traveling, the rotation of the HST 35 can be completely canceled by the electric motor 22. Therefore, even when the vehicle is traveling at high speed, the rear wheel 21 on the inner ring side can be surely decelerated to a predetermined speed during turning, and smooth turning can be performed.

  Further, if the vehicle turns when the traveling speed is high, the vehicle body becomes unstable. However, according to the above configuration, the traveling speed of the entire vehicle body is automatically reduced by operating the steering handle 10. Therefore, the safety at the time of turning can be improved.

  Note that the deceleration process of the HST 35 by the trunnion operation motor 31 described above is performed only when the vehicle body is traveling at a traveling speed equal to or higher than the limit motor vehicle speed. That is, when the vehicle speed is low, the trunnion operation motor 31 is not driven even when the steering handle 10 is operated, so that the vehicle can turn quickly without reducing the speed.

  By the way, in the rice transplanter 1 of this embodiment, since the electric motors 22L and 22R are provided in the rear wheels 21L and 21R as described above, the rotational speeds of the left and right rear wheels 21L and 21R are individually controlled. Further, it is possible to further improve the running performance. Focusing on this point, in the present embodiment, processing for decelerating the rotation of the wheel when slip occurs is performed as follows.

  As shown in FIG. 2, the rice transplanter 1 includes axle sensors 51L and 51R and torque detectors 54L and 54R. The axle sensors 51L and 51R are configured to detect the rotational speed of the axles 34L and 34R. The torque detectors 54L and 54R are configured to detect the torques of the electric motors 22L and 22R, respectively. And the detected value of the axle sensor 51 and the torque detection part 54 is comprised so that it may be transmitted to the control part 40 and the slip ratio estimation part 43. FIG.

  The slip ratio estimation unit 43 is the axle rotation speed detected by the axle sensor 51, the torque of the electric motor 22 detected by the torque detection unit 54, and the vehicle model of the rice transplanter 1 stored in advance (data such as vehicle body weight). Based on the above, the friction coefficient μ between the road surface and the wheel and the slip ratio are estimated. Further, the slip ratio estimated by the slip ratio estimation unit is configured to be transmitted to the control unit 40.

  The control unit 40 monitors the detection value of the torque detection unit 54. When the torque of the electric motor 22 detected by the torque detector 54 is suddenly reduced, it is determined that a slip has occurred in the rear wheel 21 on the side where the torque is reduced. When detecting the occurrence of slip, the control unit 40 increases the rotational speed of the corresponding electric motor 22 so as to decelerate the rear wheel 21 on the side where the slip has occurred and keep the slip ratio within a predetermined range. Thereby, it is possible to prevent the wheels from slipping due to the slip, so that the running performance is improved and the field is hardly damaged.

  Further, when the wheel rotation speed is reduced by the electric motor 22 when slip occurs, the HST 35 may be reduced by driving the trunnion operation motor 31 at the same time. According to this, since the output of the electric motor 22 required for the traction control can be reduced, slipping can be effectively prevented even with a small motor.

  Such traction control is difficult with a configuration that shifts the vehicle speed using only the HST (such as a conventional HMT transmission), but the left and right wheels are equipped with electric motors 22 that are excellent in responsiveness and controllability. This is possible for the first time by the feature of the present embodiment in which the left and right wheels can be individually subjected to deceleration control.

  As described above, the rice transplanter 1 of this embodiment includes the engine 2, the electric motor 22, the HST 35, the two rear wheels 21, the differential device 23, and the control unit 40. The HST 35 changes the output of the engine 2. The differential device 23 outputs differential power between the output of the HST 35 and the output of the electric motor 22 to the rear wheel 21. The control unit 40 controls the rotation speed of the electric motor 22. Further, the output of the engine 2 is substantially constant. And the control part 40 rotationally drives the said electric motor 22 only in the direction which cancels the driving force of HST35.

  As a result, the HST 35 and the electric motor 22 can be used together to shift the output of the engine 2 and transmit it to the rear wheels 21. Accordingly, since the speed of the engine 2 is decelerated by the HST 35 and then the electric motor 22 decelerates, the speed is changed in two stages, so that a small motor can be used and the cost can be reduced. . Further, since the electric motor 22 is rotationally driven only in the direction in which the driving force of the HST 35 is canceled, a smaller motor can be used as compared with the configuration in which the vehicle body is actively moved by the driving force of the electric motor 22. Cost can be reduced.

  Moreover, in the rice transplanter 1 of this embodiment, the rear wheels 21L and 21R are disposed so as to correspond to the left and right sides of the vehicle body. The electric motors 22L and 22R are provided on the left and right sides of the vehicle body corresponding to the rear wheels 21L and 21R, respectively. The differential devices 23L and 23R are provided on the left and right sides of the vehicle body corresponding to the electric motors 22L and 22R, respectively.

  Thereby, since the electric motor 22 is provided corresponding to each of the left and right rear wheels 21, it becomes possible to control each of the rear wheels 21 to be individually decelerated according to the situation, and to improve the traveling performance of the rice transplanter 1. Can do. Further, by shifting with the left and right electric motors 22, the traveling performance required for the rice transplanter 1 can be reduced with a low output and less expensive motor than when shifting both the left and right wheels with a single electric motor. Can be secured.

  The rice transplanter 1 according to the present embodiment includes a steering handle 10 and a transmission lever 12. The transmission ratio of the HST 35 is changed according to the operation amount of the transmission lever 12. Further, the control unit 40 controls the rotational speed of the electric motor 22 on the corresponding side to increase as the operation amount from the neutral position of the steering handle 10 increases.

  Thereby, when the vehicle body turns, the rear wheel 21 on the corresponding side can be decelerated by increasing the speed of the electric motor 22, so that the turning performance is improved and a smooth turning operation is possible. Further, the speed when traveling straight can be changed by changing the speed ratio of the HST 35. In other words, the small electric motor 22 can be used by configuring so that the speed change by the electric motor 22 is not performed during straight traveling.

  Moreover, the rice transplanter 1 of this embodiment is comprised as follows. That is, when the steering handle 10 is operated while the vehicle body is traveling at a speed equal to or higher than the limit motor vehicle speed, the control unit 40 increases the reduction ratio of the HST 35. At the same time, the control unit 40 controls the rotational speed of the electric motor 22 on the corresponding side to increase as the operation amount from the neutral position of the steering handle 10 increases.

  As a result, when a turning operation is performed while traveling at a high speed, the speed of the vehicle body can be reduced by the HST 35, so that it is possible to safely perform a turning while preventing the turning operation from being performed at a high speed. . In addition, since the rear wheel 21 on the corresponding side is decelerated by the electric motor 22 after being decelerated by the HST 35, the effect of improving the turning performance of the work implement can be exhibited even with a small motor.

  Moreover, the rice transplanter 1 of the present embodiment has a torque detector 54 that detects the torque of the electric motor 22. When the torque of the electric motor 22 decreases, the control unit 40 increases the rotational speed of the electric motor 22 and increases the reduction ratio of the HST 35.

  That is, since the electric motor 22 is excellent in responsiveness, accurate traction control is possible. Therefore, by configuring as described above, when slip occurs in the rear wheel 21, it is possible to accurately control the rear wheel 21 to decelerate and recover from the slip. Further, by using the control for decelerating the vehicle speed by the HST 35 when the slip occurs, the idling of the rear wheel 21 can be appropriately prevented even with a small motor.

  Moreover, in the rice transplanter 1 of this embodiment, the differential device 23 is a planetary gear type differential device. The driving force of the electric motor 22 is input to the sun gear 25 included in the differential device 23, the driving force from the HST 35 is input to the planetary carrier 27, and the rear wheel is connected to the ring gear 28. 21 are connected to each other.

  Thereby, the difference between the outputs of the HST 35 and the electric motor 22 can be output to the rear wheel 21.

  Although the preferred embodiment of the present invention has been described above, the above configuration can be changed as follows, for example.

  The continuously variable transmission is not limited to HST, but may be, for example, a belt-type CVT (continuously variable transmission) or the like. However, it is preferably a continuously variable transmission that can perform zero start smoothly.

  The differential device 23 and the electric motor 22 may be provided not only for the rear wheels 21L and 21R but also for all four wheels. When comprised in this way, it is preferable from a viewpoint that the control which decelerates all the wheels separately at the time of turning and the occurrence of a slip becomes possible.

  The steering operation tool is not limited to a steering wheel type, and may be a lever type steering operation tool that can be rotated to the left and right, for example. In this case, it is conceivable to perform control so that the inner wheel is decelerated in proportion to the rotation angle of the lever. Further, the speed change operation tool is not limited to the lever type, and may be a pedal type speed change operation tool, for example.

  For example, a mechanical auxiliary transmission for switching between high speed / low speed and the like may be provided between the engine 2 and the HST 35.

  Needless to say, the differential device is not limited to the planetary gear type, and may be a differential device having another configuration.

  In the planetary gear type differential device, the driving force from the HST 35, the driving force from the electric motor 22, and the output to the axle 34 are connected to any of the sun gear 25, the planetary carrier 27, and the ring gear 28. Also good.

  The control unit 40 and the slip ratio estimation unit 43 are not configured separately, and the functions of the control unit 40 and the slip ratio estimation unit 43 may be realized by, for example, one microprocessor.

  The configuration of the present invention is not limited to the rice transplanter, and can be applied to other work machines such as a tractor and a snowplow. In addition, the working machine is not limited to a working machine having a wheel type traveling device, and may be a working machine having a crawler type traveling device, for example.

1 Rice transplanter (work machine)
2 Engine 10 Steering handle (steering tool)
12 Shift lever (shift operating tool)
21 Rear wheel 22 Electric motor 23 Differential device 35 HST (continuously variable transmission)
40 Control unit 54 Torque detection unit

Claims (6)

Engine,
An electric motor;
A continuously variable transmission for shifting the output of the engine;
Multiple wheels,
A differential that outputs differential power between the output of the continuously variable transmission and the output of the electric motor to the wheels;
A control unit for controlling the rotation speed of the electric motor;
With
The engine output is substantially constant,
The work unit characterized in that the control unit rotationally drives the electric motor only in a direction to cancel the driving force of the continuously variable transmission. The work machine according to claim 1,
The wheels are arranged to correspond to each other on the left and right sides of the vehicle body,
The electric motor is provided on each of the left and right sides of the vehicle body corresponding to the wheels,
The working machine characterized in that the differential device is provided on each of the left and right sides of the vehicle body corresponding to the electric motor. The work machine according to claim 2,
A steering operation tool,
A shift operation tool;
With
The transmission ratio of the continuously variable transmission is changed according to the operation amount of the transmission operation tool,
The said control part controls so that the rotational speed of the electric motor of a corresponding side may be increased according to the amount of operations from the neutral position of the said steering operation tool becoming large. The work machine according to claim 3,
When the steering operation tool is operated while the vehicle body is traveling at a speed equal to or higher than a predetermined speed, the control unit increases the reduction ratio of the continuously variable transmission, and the steering operation tool A work machine that controls to increase the rotation speed of the electric motor on the corresponding side as the operation amount from the neutral position increases. The working machine according to any one of claims 1 to 4,
A torque detector for detecting the torque of the electric motor;
When the torque of the electric motor decreases, the control unit increases the rotation speed of the electric motor and increases the reduction ratio of the continuously variable transmission. The working machine according to any one of claims 1 to 5,
The differential is a planetary gear type differential,
One of the continuously variable transmission, the electric motor, and the wheel is connected to each of the sun gear, the planetary carrier, and the ring gear included in the differential device.

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