JP2007039031A - Travel drive device of working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a travel drive device of a working vehicle capable of preventing a paddy field surface by the drag or the slip of wheels when making a turn of the working vehicle while the traveling speed of a front wheel is agreed with that of a rear wheel. <P>SOLUTION: A closed circuit is constituted by performing the fluid coupling of a first hydraulic pump P1 to be driven by the power of an engine E with a first hydraulic motor M1 to transmit the power to a transmission case 1. An output shaft of the first hydraulic motor M1 is interlockingly connected to a transmission. One output after the speed change is transmitted t a main drive wheel 5 via a first differential gear device D1, and the other output drives a second hydraulic pump P2 to drive right and left sub drive wheels 6 by a pair of right and left hydraulic motors M3 which are fluid-coupled with the second hydraulic pump P2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  According to the present invention, the work vehicle is shifted by the HST transmission, the main drive wheel is driven, the hydraulic pump is driven after the shift, and the hydraulic motor is operated by the pressure oil to drive the auxiliary drive wheel. Related to technology.

Conventionally, a hydraulic pump is driven by power from an engine, fluidly connected to the hydraulic pump via a closed circuit, and one of the output shafts of the hydraulic motor is connected to a differential device via an auxiliary transmission. Power is transmitted to drive the main drive wheel (rear wheel or front wheel), and on the other hand, power is transmitted from the output shaft of the hydraulic motor to the differential device via the transmission shaft to drive the auxiliary drive wheel (front wheel or rear wheel). This technique is known.
JP-A-8-2279 Japanese Utility Model Publication No. 60-32127

  However, in the conventional technique, when the rear wheel (main drive wheel) is driven from the output shaft of the hydraulic motor via the auxiliary transmission device, the rotation speed of the front wheel (sub drive wheel) and The number of rotations of the rear wheels is different, dragging occurs and the turf surface is damaged in the field scene, especially in the case of mowers for mowing the lawn. Even if the traveling speeds of the front wheels and the rear wheels are matched, if the vehicle turns, the vehicle will turn around the inside of the vehicle turning, so in the case of 4WD (4-wheel drive), the front wheels rotate. However, dragging occurs late. In the case of 2WD, when one of the left and right wheels is idle during traveling, the driving force is not transmitted to the other, and the field scene is damaged by slipping.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  In claim 1, a first hydraulic pump driven by engine power and a first hydraulic motor that transmits power to the transmission case are fluidly connected to form a closed circuit, and an output shaft of the first hydraulic motor is provided. It is linked to the transmission, and the output after this shift is transmitted to the main drive wheel, one through the first differential device, and the other drives the second hydraulic pump to the second hydraulic pump. The left and right auxiliary drive wheels are driven by a pair of left and right hydraulic motors that are fluidly connected.

  In claim 2, the second hydraulic pump or the left and right hydraulic motors are of a variable displacement type, the swash plate thereof is interlocked with the steering handle, and the driving of the auxiliary driving wheel is performed at a rotational speed corresponding to the turning of the steering handle. did.

  According to a third aspect of the present invention, a flow rate change valve unit is provided in an oil feed path between the second hydraulic pump and the left and right hydraulic motors, the flow rate change valve unit and the steering handle are linked and connected to each other according to the turning of the steering handle. The oil amount to the left and right hydraulic motors was controlled.

  Since the present invention is configured as described above, the following effects can be obtained.

  As in claim 1, a first hydraulic pump driven by engine power and a first hydraulic motor that transmits power to the transmission case are fluidly connected to form a closed circuit, and an output shaft of the first hydraulic motor is connected to the first hydraulic motor. It is linked to the transmission, and the output after this shift is transmitted to the main drive wheel, one through the first differential device, and the other drives the second hydraulic pump to the second hydraulic pump. The secondary drive wheels are driven by the fluid-connected hydraulic motor via the second differential device, so the main drive shaft and the secondary drive shaft are fluidly connected, and there is no need to arrange the shaft, and the main drive The space between the shaft and the auxiliary drive shaft can be increased, and the mounting space for the mid-mount work machine can be increased.

  According to a second aspect of the present invention, a first hydraulic pump driven by engine power and a first hydraulic motor that transmits power to the transmission case are fluidly connected to form a closed circuit, and an output shaft of the first hydraulic motor is provided. It is linked to the transmission, and the output after this shift is transmitted to the main drive wheel, one through the first differential device, and the other drives the second hydraulic pump to the second hydraulic pump. Since the left and right auxiliary drive wheels are driven by a pair of left and right hydraulic motors that are fluidly connected, the axle case of the auxiliary drive shaft can be made compact, and the weight can be reduced.

  According to a third aspect of the present invention, the second hydraulic pump or the left and right hydraulic motors are of a variable displacement type, and the auxiliary drive wheels are driven at a rotational speed corresponding to the turning of the steering handle, or the second hydraulic pump and the left and right hydraulic pressures are driven. A flow rate change valve unit is installed in the oil supply path between the motors, and the flow rate change valve unit and the steering handle are linked and connected, and the oil amount to the left and right hydraulic motors is controlled according to the turning of the steering handle. The auxiliary drive shaft has a rotational speed corresponding to the turning, and there is no dragging and the turning can be smoothly performed.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall side view of a work vehicle in which the travel drive device of the present invention is applied to a mower, FIG. 2 is a schematic view showing another reference example of the travel drive device of the present invention, and FIG. 4 is a hydraulic circuit diagram of another reference example, FIG. 5 is a schematic diagram when power is transmitted from the transmission case to the auxiliary drive wheel via the transmission shaft, and FIG. 6 is a second diagram of the travel drive device. FIG. 7 is a schematic diagram showing another reference example of the travel drive device, FIG. 8 is a schematic diagram showing another reference example of the travel drive device, and FIG. 9 is a first embodiment of the travel drive device. FIG. 10 is a schematic diagram showing a second embodiment of the travel drive device, FIG. 11 is a schematic diagram showing a third embodiment of the travel drive device, and FIGS. 12 to 14 are diagrams showing a flow rate changing valve unit. FIG. 15 is a schematic view showing a fourth embodiment of the travel drive apparatus, and FIG. 16 shows a fifth embodiment of the travel drive apparatus. Schematic view, FIG. 17 is a schematic diagram showing another reference example of the travel drive device.

  A configuration example in which the traveling drive device of the present invention is applied to a mower will be described. The front wheels are the main drive wheels 5 and the rear wheels are the sub drive wheels 6. The sub drive wheels 6 are also steered wheels. The main drive wheel 5 is supported on the front portion of the body frame 19, the sub drive wheel 6 is supported on the rear portion, and a front reel mower 8F (one or more) is disposed in front of the main drive wheel 5 to be movable up and down. A side reel mower 8S is disposed between the main drive wheel 5 and the sub drive wheel 6 so as to be movable up and down. An operation unit A is disposed on the front part of the body frame 19, and the engine E is placed on the rear part of the body frame 19 and covered with a bonnet.

  Next, a first configuration example of the drive configuration of the main drive wheel 5 and the sub drive wheel 6 will be described. In FIG. 2, a variable displacement type first hydraulic pump P1 is provided on the output shaft of the engine E, and a constant displacement type first hydraulic motor M1 is attached to the transmission case 1 to provide the first hydraulic pump. P1 and the first hydraulic motor M1 are fluidly connected by piping or an oil path to form a first HST transmission, and the output shaft of the first hydraulic motor M1 is connected to the input shaft 2 of the mission case 1. ing. A sub-transmission device 3 is housed in the transmission case 1 and one of the output shafts 4 of the sub-transmission device 3 is transmitted to the first differential device D1 via a gear to drive the main drive wheels 5 and 5. The other output shaft 4 is connected to the input shaft 9 of the second hydraulic pump P2 via a clutch 7 comprising an overrunning clutch or an ON / OFF clutch. However, the clutch 7 is not between the output shaft 4 and the input shaft 9, but the output side of a second hydraulic motor M2 described later (FIG. 18), or the output side of a pair of left and right hydraulic motors M3 and M3 (FIG. 19). It can also be provided.

  For example, as shown in FIG. 2, the auxiliary transmission 3 has a large-diameter gear 10 and a small-diameter gear 11 fixed on the input shaft 2, while a double sliding gear 12 is slidable on the output shaft 4. And are externally fitted so as not to rotate with each other. High speed rotation is obtained by meshing one gear 12a of the double sliding gear 12 with the large diameter gear 10, and low speed rotation is obtained by meshing the other gear 12b with the small diameter gear 11. Is possible. However, the auxiliary transmission device 3 is not limited to the two-speed shift, and may be a one-stage or more multi-stage shift or a continuously variable transmission.

  A gear 13 is fixed to one end of the output shaft 4, the gear 13 is engaged with a gear 15 on a reduction shaft 14, a bevel gear 16 is fixed to the reduction shaft 14, and the bevel gear 16 is It meshes with the ring gear 17 of the first differential device D1. The axles 18L and 18R protrude from the first differential device D1, and main drive wheels 5 and 5 are fixed to the other ends of the axles 18L and 18R. In this way, the first hydraulic motor M1 is driven and the power after being shifted by the auxiliary transmission 3 is transmitted from the output shaft 4 to the first differential device D1 via the gears 13 and 15 and the bevel gear 16. Then, the main drive wheels 5 and 5 are driven.

  However, as shown in FIG. 3, the main drive wheels 5 and 5 can be driven at a reduced speed by interposing a reduction case 29 containing reduction gears (bull gears) on both sides of the axles 18L and 18R. The transmission ratio can be reduced and the size can be reduced by reducing the reduction ratio of D1, and the tread can be changed by interposing the reduction case 29.

  By projecting the deceleration case 29 forward, a space can be formed between the left and right deceleration cases 29 and 29, and the front reel mower 8FM is disposed in the space between the deceleration cases 29 and 29. Therefore, when three reel mowers 8FL, 8FM, and 8FR are installed in front of the machine, the central reel mower can be placed between the left and right front wheels, so that the overall length can be shortened and the arm for raising and lowering can also be shortened. The mechanism can also be placed in the space, protected, and the space can be used effectively.

  The case where the clutch 7 is an overrunning clutch will be described. When the rotational speed of the output shaft 4 changes, the overrunning clutch becomes “contacted” and transmits power to the input shaft 9, regardless of the rotational direction. When the rotation speed of the output shaft 4 is changed, it is “contact”, and when the rotation is steady, it is “disconnected”. In addition, when the clutch 7 is an ON / OFF clutch, the clutch 7 can be manually turned to “disconnect” or “contact”, or the electromagnetic clutch can be turned ON / OFF by operating a switch. Alternatively, when the rotational speeds of the left and right axles 18L and 18R are detected, and the rotational speed difference is equal to or greater than a set value, it can be configured to be “contact”.

  The second hydraulic pump P2 is fluidly connected to the second hydraulic motor M2 via pipings 20 and 20 to form a closed circuit, thereby forming a second HST transmission. The second hydraulic pump P2 and the second hydraulic motor M2 can be either a fixed volume type or a variable volume type, and one can be a variable volume type and the other can be a constant volume type. You can also. A bevel gear 22 is fixed to the output shaft 21 of the second hydraulic motor M2, and the bevel gear 22 meshes with the ring gear 24 of the second differential device D2 in the rear axle housing 23, and the second differential device D2 is engaged. The auxiliary drive wheels 6 and 6 are fixed to both ends of the axles 25L and 25R that protrude more to the left and right.

  As shown in FIG. 4, in the hydraulic circuit of the first and second HST transmissions, a charge pump CP1 is disposed in the first hydraulic pump P1 and is driven simultaneously. The hydraulic motor M1 is connected to oil passages 26a and 26b, the discharge oil passage of the charge pump CP1 is connected to a charge relief valve 27, and the oil passages 26a and 26b are connected via check valves 28 and 28. When the pressure oil in the closed circuit decreases, hydraulic oil can be replenished. The second HST transmission is similarly configured. Further, the work implement can be driven by the pressure oil discharged from the charge pump CP1 of the first HST transmission.

  In such a configuration, the rotation of the output shaft of the first hydraulic motor M1 is changed steplessly by changing the angle of the movable swash plate of the first hydraulic pump P1, and the rotation proportional to the rotation is the main. It is transmitted to the drive wheels 5 and 5 to drive the work vehicle. When the work vehicle is traveling straight ahead, the second hydraulic pump P2 is not driven, and the auxiliary driving wheels 6 and 6 are in an idle state so that drag does not occur and the field scene (turf surface) may be damaged. Absent.

  Further, when one side of the main drive wheels 5 or 5 falls into a muddy or indented state during running, a change occurs in the rotational speed of the output shaft 4 and the rotational speed of the input shaft 9 of the second hydraulic pump P2. . Then, when the clutch 7 is an overrunning clutch, it is automatically “contacted” to drive the second hydraulic pump P2, and the second hydraulic motor M2 is actuated to turn the auxiliary drive wheels 6 and 6 on. It can be driven to escape from the mud. However, as shown in FIG. 5, the configuration can be simplified as a configuration in which power is transmitted to the second differential device D <b> 2 via the universal joint 38 and the transmission shaft 39 to the output shaft 9 of the clutch 7. In the case of FIG. 18, when the second hydraulic pump P2 is operated, the second hydraulic motor M2 is also operated, and the clutch 7 is automatically activated when one side of the main drive wheels 5, 5 slips. “Contact” is established to transmit power to the second differential device D2 to drive the auxiliary driving wheels 6 and 6. In the case of FIG. 19, when the second hydraulic pump P2 is operated, the pair of hydraulic motors M3 and M3 are also operated, and when one side of the main drive wheels 5 and 5 slips, the clutches 7 and 7 are engaged. It automatically becomes “contact” and drives the auxiliary drive wheels 6 and 6.

  Next, a second welfare example of the drive configuration of the auxiliary drive wheel 6 will be described with reference to FIG. When the clutch 7 is an ON / OFF clutch, and the ON / OFF clutch is an electromagnetic clutch 30 that can be operated by a switch or the like, the second hydraulic pump P2 or the second hydraulic motor M2 of the second HST transmission is used. One or both of them is of a variable displacement type, and the movable swash plate and the electromagnetic clutch 30 are interlocked and connected to the steering handle 31.

  In such a configuration, when the electromagnetic clutch 30 is turned OFF and the front wheel drive is only 2WD, the auxiliary drive wheels 6 and 6 are steered and rotated by the rotation of the steering handle 31 as in the conventional case, and the main drive wheels 5 and 5 are rotated. When slipping occurs, the electromagnetic clutch 30 is “contacted” by the operation of the switch to escape as 4WD. However, in this structure, an overrunning clutch can be provided in parallel with the electromagnetic clutch 30, and this configuration eliminates the need to switch to 4WD. In addition, when the electromagnetic clutch 30 is turned on to increase the grip force and perform stable running except when the vehicle is stuck (in the muddy area), the drive speeds of the main drive wheel 5 and the sub drive wheel 6 coincide when traveling straight ahead. The movable swash plate is changed as described above. When the steering handle 31 is turned to turn, the swash plate is also turned in accordance with the turning angle to increase the number of rotations on the auxiliary drive wheels 6 and 6 side to prevent dragging. In the case of FIG. 20, when a switching valve V is provided between the pipings 20 and 20, the switching valve V is interlocked with the steering handle 31, and the steering handle 31 is turned to turn. The switching valve V is switched to allow the pipings 20 and 20 to communicate with each other, thereby preventing a difference in rotational speed between the auxiliary driving wheels 6 and 6 and the main driving wheels 5 and 5 from being dragged. In addition, a means for detecting the hydraulic pressure of the piping 20, 20 is provided, and when the second hydraulic motor M2 is turned, the pump action is caused by the rotation at the time of turning, causing a pressure change, and when the pressure changes. It can also be set as the structure which connects between piping 20 * 20.

  A third configuration example of the configuration in the mission case will be described with reference to FIG. In the configuration within the mission case 1 as shown in FIG. 2 described above, the input shaft 2, the output shaft 4, and the input shaft 9 are arranged in a direction perpendicular to the axles 18L and 18R. 2 and the output shaft 4 and the input shaft 9 are arranged in parallel with the axles 18L and 18R, and a spur gear 16 'is used instead of the bevel gear 16 of the first differential device D1. Similarly, the ring gear 17 is a spur gear 17 '. Other configurations are the same as described above. Further, the third configuration example of FIG. 7 is configured such that the hydraulic pump P1 and the hydraulic motor M1 are disposed on the opposite side with respect to the center of the machine body, and the fourth configuration example illustrated in FIG. 8 includes the hydraulic pump P1 and the hydraulic motor M1. It arranges on the same side, and is set as the structure arranged compactly.

  In the first configuration example shown in FIG. 9, instead of the second differential device D2, hydraulic motors M3 and M3 are provided on the left and right auxiliary drive wheels 6 and 6, respectively, and fluidly connected in parallel with the second hydraulic pump P2. It is set as the structure which drives. In another reference example shown in FIG. 10, the hydraulic motors M3 and M3 are variable displacement hydraulic motors, and drag is performed by changing the number of rotations of the auxiliary drive wheels 6 and 6 in accordance with the amount of rotation of the steering handle 31 when turning. Try to prevent.

  Another reference example shown in FIG. 11 is one in which a flow rate change valve unit 44 is provided in the oil feed path from the second hydraulic pump P2 to the hydraulic motors M3 and M3 provided in the auxiliary drive wheels 6 and 6. The change valve unit 44 changes the flow rate in accordance with the rotation of the steering handle 31 so that it can be smoothly turned without dragging. That is, as shown in FIG. 12, the flow rate changing valve unit 44 has a communication oil passage 45c between oil passages 45a and 45b constituting a closed circuit, and a variable throttle 32 is provided in the communication oil passage 45c. The variable throttle 32 is interlocked with the steering handle 31, and the variable throttle 32 is closed in accordance with the amount of rotation of the steering handle 31 to prevent dragging by increasing the rotational speed of the hydraulic motors M3 and M3. .

  Further, the flow rate changing valve unit 44 may be configured as shown in FIG. That is, the flow control valves 33 and 33 are connected in series to the oil passages 45a and 45b, the check valves 34 and 34 are connected in parallel to the flow control valves 33 and 33, and further to the primary side of the flow control valves 33 and 33. The variable throttles 32 and 32 and the check valves 35 and 35 are connected in series to the communication oil passages 45c and 45c communicating with each other, arranged so as to flow in opposite directions, and the flow rate returning from the high pressure side to the low pressure side of the closed circuit In the same manner as described above, the number of rotations of the rear wheels is increased when the steering handle is rotated.

  Further, the flow rate changing valve unit 44 may be configured as shown in FIG. That is, the variable constant ratio diversion valves 36 and 36 are provided in the oil passages 45a and 45b, while the switching valves 37 and 37 are connected in series to the oil passages 45d and 45d that connect the hydraulic motors M3 and M3. The secondary sides of the constant ratio diversion valves 36 and 36 are connected to the primary side and the secondary side of the switching valves 37 and 37. The variable constant ratio diverter valves 36 and 36 can change the oil feed amount by turning the steering handle 31. That is, when the switching valves 37 and 37 are switched to block the flow passages of the oil passages 45d and 45d to be diff-locked in this way, an equal amount of pressure oil is supplied from the variable constant ratio diversion valves 36 and 36 to the hydraulic motor. The oil is fed to M3 and M3, and the left and right rear wheels are driven at the same rotational speed.

  In the fourth embodiment shown in FIG. 15, the hydraulic pump P2 is a variable displacement hydraulic pump, and its swash plate is connected to an actuator 40 such as a hydraulic cylinder or a solenoid. The actuator 40 is controlled by a control unit 41, and the actuator When 40 is a hydraulic cylinder, a servo valve is provided in the control unit 41 for control. The control unit 41 detects the pressure sent to the left and right hydraulic motors M3 and M3. If there is a difference between the left and right hydraulic pressures, the control unit 41 determines that the vehicle is turning. -Increase the number of rotations of 6 to prevent dragging.

  The fifth embodiment shown in FIG. 16 is an embodiment in which the control unit 41 can be switched in two stages using two switching valves instead of the servo valves. Connected between the actuator 40 and the charge pump CP 2, the switching valve 42 is switched by a pilot oil passage 46 from the differential pressure detection valve 43. The differential pressure detection valve 43 is switched by the pressure oil in the pilot oil passages 47 and 47 from the oil passages 45d and 45d connecting the hydraulic motors M3 and M3, and is switched when there is no pressure difference between the oil passages 45d and 45d. The valve 42 and the differential pressure detection valve 43 are not switched and are in a straight traveling state, and when there is a pressure difference, it is during turning. The differential pressure detection valve 43 is switched, and pressure oil flows into the pilot oil passage 46 and the switching valve 42. And the actuator 40 is driven to change the oil amount of the second hydraulic pump P2 to increase the rotational speed of the hydraulic motors M3 and M3 so that there is no drag. However, in 4th Example and 5th Example, the control part 41 and the actuator 40 can also be attached to the hydraulic motor M side.

  Moreover, it can also comprise like the 5th structural example shown in FIG. This fifth configuration example is an embodiment in which the auxiliary drive wheel 6 is one wheel. In this case, the second differential device D2 and one hydraulic motor M3 can be omitted, the configuration can be simplified, and a small mower can be obtained. Is suitable.

1 is an overall side view of a work vehicle in which a traveling drive device of the present invention is applied to a mower. It is a schematic diagram which shows the other reference example of the traveling drive apparatus of this invention. It is a schematic diagram at the time of attaching a deceleration case to an axle. It is a hydraulic circuit diagram of another reference example. It is a schematic diagram at the time of transmitting motive power from a transmission case to a sub drive wheel via a transmission shaft. It is a schematic diagram which shows the other reference example of a traveling drive apparatus. It is a schematic diagram which shows the other reference example of a traveling drive apparatus. It is a schematic diagram which shows the other reference example of a traveling drive apparatus. It is a schematic diagram which shows 1st Example of a traveling drive apparatus. It is a schematic diagram which shows 2nd Example of a traveling drive apparatus. It is a schematic diagram which shows 3rd Example of a traveling drive apparatus. It is a figure which shows a flow volume change valve unit. It is a figure which shows the other Example of a flow volume change valve unit. It is a figure which shows the other Example of a flow volume change valve unit. It is a schematic diagram which shows 4th Example of a traveling drive apparatus. It is a schematic diagram which shows 5th Example of a traveling drive apparatus. It is a schematic diagram which shows the other reference example of a traveling drive apparatus. It is a schematic diagram which shows the structural example which provided the clutch in the output side of the 2nd hydraulic motor M2. It is a schematic diagram which shows the structural example which provided the clutch in the output side of a pair of hydraulic motor M3 * M3. It is a schematic diagram which shows the structural example which has arrange | positioned the switching valve switched by rotation of a steering handle during piping between a 2nd pump and a 2nd hydraulic motor.

Explanation of symbols

P1 1st hydraulic pump P2 2nd hydraulic pump M1 1st hydraulic motor M2 2nd hydraulic motor D1 1st differential device D2 2nd differential device 1 Mission case 3 Subtransmission 5 Main drive wheel 6 Subdrive Wheel 7 Clutch 31 Steering handle 44 Flow rate change valve unit

Claims (3)

  A first hydraulic pump (P1) driven by the power of the engine (E) and a first hydraulic motor (M1) that transmits power to the transmission case (1) are fluidly connected to form a closed circuit, and the first circuit The output shaft of one hydraulic motor (M1) is linked to the transmission, and the output after this shift is transmitted to the main drive wheel (5) through the first differential device (D1), Drives the second hydraulic pump (P2), and drives the left and right auxiliary drive wheels (6, 6) from a pair of left and right hydraulic motors (M3, M3) fluidly connected to the second hydraulic pump (P2). A traveling drive device for a work vehicle, characterized in that:   The traveling drive device for a work vehicle according to claim 1, wherein the second hydraulic pump (P2) or the pair of left and right hydraulic motors (M3, M3) is a variable displacement type, and the swash plate is interlocked with the steering handle (31). A traveling drive device for a work vehicle, characterized in that the driving speed of the auxiliary drive wheels (6, 6) is set to a rotational speed corresponding to the turning of the steering handle (31).   The travel drive device for a work vehicle according to claim 1, wherein a flow rate change valve unit (44) is provided in an oil feed path between the second hydraulic pump (P2) and the pair of left and right hydraulic motors (M3, M3). The flow rate changing valve unit (44) and the steering handle (31) are interlockedly connected, and the amount of oil to the pair of left and right hydraulic motors (M3, M3) is controlled according to the turning of the steering handle (31). A traveling drive device for a working vehicle.

Images