JP2013170588A - Transaxle and wheel type work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transaxle that transmits rotational power operatively transmitted from a drive source to a matched pair of first and second drive wheels, in which a range of a drive rotational speed difference between the first and second drive wheels is enlarged.SOLUTION: A transaxle includes: a differential device 23 that can differentially transmit rotational power operatively input from a drive source 2 to first and second output shafts 22(1), 22(2), respectively; and a speed-up device 24 that can increase the speed and transmit the rotational power operatively input from the drive source to the first and second output shafts. The differential device includes a differential locking member 61 that can set at a differential locking position and at a differential position. The speed-up device includes first and second speed-up transmission routes 50(1), 50(2) that can synchronously increase the speed and transmit the rotational power of an input gear 41 of the differential device where the rotational power is operatively input from the drive source, to the first and second output shafts. First and second clutches 51(1), 51(2) are inserted in the first and second speed-up transmission routes, respectively.

Description

  The present invention relates to a transaxle that transmits rotational power operatively transmitted from a drive source to a pair of left and right first and second drive wheels, and a wheeled work vehicle including the transaxle.

  A transaxle is widely used that differentially transmits rotational power transmitted from a driving source, generally via a transmission, to a pair of left and right first and second driving wheels via a differential. (For example, refer to Patent Document 1).

  The conventional transaxle has a differential state in which a differential lock member is positioned at a differential position and a differential lock position to differentially transmit the input rotational power in accordance with the traveling load of the pair of first and second drive wheels. A differential lock state in which the rotational power is forcibly synchronously transmitted to the pair of first and second drive wheels can be revealed.

However, in the conventional transaxle, the difference between the driving rotational speeds of the first and second driving wheels in the differential state depends on the traveling load of the first and second driving wheels, and further, the driving rotational speed The difference is limited within the range of the rotational speed of the input rotational power at the maximum.
That is, in the differential state in the conventional transaxle, when the rotational speed of the input rotational power is N, the rotational speed difference between the first and second driving wheels is only N at the maximum.

JP 2003-185000 A

  The present invention has been made in view of such a conventional technique. In a transaxle that transmits rotational power operatively transmitted from a drive source to a pair of left and right first and second drive wheels, the first and second It is an object of the present invention to provide a transaxle that can expand the range in which the drive speed difference between the two drive wheels can be larger than the range of the rotational speed of the input rotational power.

  The present invention also provides a wheel-type working vehicle having a transaxle that transmits rotational power operatively transmitted from a drive source to a pair of left and right first and second drive wheels. It is another object of the present invention to provide a wheeled working vehicle that can expand the range in which the difference in the driving rotational speed can be larger than the rotational speed range of the rotational power input to the transaxle.

  In order to achieve the one object, the present invention provides a transaxle that transmits rotational power operatively transmitted from a drive source to a pair of left and right first and second drive wheels. The first and second output shafts are coaxially arranged in a state of being operatively connected to the two drive wheels, respectively, and the rotational power operatively input from the drive source is differentiated between the first and second output shafts. A differential device capable of transmitting power, and a speed increasing device capable of transmitting the rotational power operatively input from the drive source to the first and second output shafts. An input gear whose axis is coaxial with the first and second output shafts and operatively inputs rotational power from the drive source, revolves as the input gear rotates, and is based on the rotational axis A bevel pinion capable of rotating about a pivot axis extending in the radial direction, At least one of the first and second side bevel gears that are supported by the first and second output shafts so as not to rotate relative to each other and engaged with the bevel pinion, and at least one of the first and second side bevel gears is the input gear. And a differential lock member capable of assuming a differential position where the side bevel gear is relatively rotatable around the rotational axis with respect to the input gear. , Having first and second speed increase transmission paths that can transmit the rotational power of the input gear to the first and second output shafts in a synchronized state, and the first and second speed increase transmission paths include A transaxle is provided in which first and second clutches are respectively inserted.

  Preferably, the first and second clutches are multi-plate clutches.

  Preferably, an axle case is provided that supports the first and second output shafts and accommodates the differential. The speed increasing device includes: a driving gear meshing with the input gear; a speed increasing driving shaft that is not rotatable relative to the driving gear; and a first speed gear supported by the speed increasing driving shaft so as to be relatively rotatable. A second intermediate gear, a first driven gear meshed with the first intermediate gear and made non-rotatable relative to the first output shaft, and meshed with the second intermediate gear and relatively rotated around the second output shaft The second driven gear disabled, the first clutch inserted between the speed increasing drive shaft and the first intermediate gear, and the power driven drive shaft and the second intermediate gear. The axle case includes an opening that allows external access to the input gear, the first driven gear, and the second driven gear. The drive gear, the speed increasing drive shaft, the first and second clutches, and the first and second intermediate gears form a unit, and the unit is connected to the drive gear, the first through the opening. A first intermediate gear and a second intermediate gear are detachably connected to the axle case so as to mesh with the input gear, the first driven gear, and the second driven gear, respectively.

  In order to achieve the other object, the present invention provides a driving source, a pair of left and right first and second driving wheels, a turning operation member, and rotational power operatively input from the driving source. A wheeled working vehicle including a transaxle that transmits toward the first and second drive wheels, a control device, and a mode switching member, wherein the transaxle is connected to the first and second drive wheels. The first and second output shafts arranged coaxially in the state of being operatively connected to each other, and the rotational power operatively input from the drive source can be differentially transmitted to the first and second output shafts. A differential device, and a speed increasing device capable of transmitting the rotational power operatively input from the drive source to the first and second output shafts, the rotational axis of the differential device being the first. Located coaxially with the first and second output shafts and operatively from the drive source Meshed with the bevel pinion, an input gear for inputting rolling power, a bevel pinion that revolves with the rotation of the input gear and that can rotate about a pivot axis extending radially with respect to the rotation axis. In the state where the first and second side bevel gears are supported on the first and second output shafts so as not to rotate relative to each other, at least one of the first and second side bevel gears is connected to the input gear with respect to the rotational axis. A differential lock position that disables relative rotation and a differential lock member that can assume a differential position that allows the at least one side bevel gear to rotate relative to the input gear about the rotation axis, and the speed increasing device includes the input The first and second speed-up transmission paths have a first and a second speed-up transmission path capable of transmitting the rotational power of the gear to the first and second output shafts in a synchronized state. First and second clutches are respectively inserted in the high speed transmission paths, the differential lock member is operated by an actuator that is controlled by electric signals, and the first and second clutches are engaged by electric signals. The control device is configured to change a normal differential mode in which the first and second clutches are disengaged and the differential lock member is positioned at a differential position in response to an artificial operation on the mode switching member, A differential lock mode in which the first and second clutches are disengaged and the differential lock member is positioned at the differential lock position and a forced differential mode are selectively displayed. In the forced differential mode, the control device moves the differential lock member to the differential lock mode. A signal from the turning sensor that detects the operation state of the turning operation member while being positioned at the differential position. Based on the above, both clutches are released when going straight, one clutch located inside the turn is released when turning, and the other clutch located outside the turn is engaged with strength according to the amount of operation of the turning operation member. A wheeled working vehicle is provided.

  Preferably, the first and second speed increasing transmission paths are configured such that the rotational speed of the first and second output shafts is 2 × N, where N is the rotational speed of the input gear.

  The transaxle according to the present invention includes a pair of first and second output shafts, a state in which rotational power operatively input from a drive source can be differentially transmitted to the first and second output shafts, and forcibly. A speed increasing device capable of transmitting the rotational power operatively input from the driving source to the first and second output shafts in a speed increasing manner in addition to the differential device that can switch the synchronously driven state by a differential lock member. And the speed increasing device has first and second speed increasing transmission paths capable of transmitting the rotational power of the input gear to the first and second output shafts in a synchronized state. First and second clutches are inserted in the first and second speed increase transmission paths, respectively.

  According to the transaxle of the present invention, the first and second clutches are disengaged, and the diff lock member is located at the diff lock position to cause the diff lock state to appear, and the first and second clutches are disengaged. And the differential lock member can be brought into the differential position to cause the differential state to appear, and one of the first and second clutches is engaged and the differential lock member is positioned to the differential position. By doing so, the driving wheel on the side of the engaged clutch is increased in speed according to the speed increasing ratio of the speed increasing transmission path, and the driving wheel on the other side of the clutch is accelerated from the input rotational power. The forced differential state in which the motor is decelerated by the corresponding speed can be displayed.

  Further, the wheel type working vehicle according to the present invention is capable of differentially transmitting a pair of first and second output shafts and rotational power operatively input from a drive source to the first and second output shafts. In addition to the differential device that can be switched forcibly and synchronously driven by the differential lock member, the rotational power operatively input from the drive source can be transmitted to the first and second output shafts at an increased speed. A transaxle having a speed increasing device, wherein the transaxle speed increasing device is capable of transmitting the rotational power of the input gear to the first and second output shafts in a synchronized state with a first speed and a second speed. An acceleration transmission path is provided, and first and second clutches are inserted in the first and second acceleration transmission paths, respectively.

  According to the wheeled work vehicle of the present invention, the first and second clutches are disengaged and the diff lock member is positioned at the diff lock position so that the diff lock state appears, and the first and second clutches are disengaged. The differential state can be caused to appear by setting the differential lock member to the differential position by setting the differential state, and further, either one of the first and second clutches is engaged and the differential lock member is set to the differential position. Therefore, the driving wheel on the side of the engaged clutch is driven to increase speed according to the speed increasing ratio of the speed increasing transmission path, and the driving wheel on the other side of the clutch is increased from the input rotational power. A forced differential state in which the motor is decelerated by the accelerated speed can be displayed.

It is a left view of the wheel type work vehicle provided with the transaxle concerning this embodiment. It is a transmission schematic diagram of the wheel type work vehicle. FIG. 3 is a cross-sectional view of a vicinity of a differential device and a speed increasing device in the transaxle. It is a control block diagram of the wheel type work vehicle.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows a left side view of a wheeled working vehicle 1 to which a transaxle 6 according to the present embodiment is applied.
FIG. 2 shows a schematic diagram of transmission of the wheel type working vehicle 1.

  As shown in FIGS. 1 and 2, the wheel-type working vehicle 1 includes a drive source 2, a pair of left and right first and second drive wheels 3 (1) and 3 (2), a turning operation member 5, The transaxle 6 transmits the rotational power operatively input from the drive source 2 toward the first and second drive wheels 3 (1) and 3 (2).

The wheeled work vehicle 1 according to the present embodiment is a tractor that can selectively switch between a two-wheel drive state and a four-wheel drive state.
Therefore, as shown in FIG. 1, the wheeled work vehicle 1 includes a machine frame 11, and a turning operation member 5 such as a round handle supported by the machine frame 11 in addition to the components. A driver's seat 12 disposed in the vicinity, a belt-type transmission 14 that is operatively driven by the drive source 2 and acts as a transmission for shifting the rotational power from the drive source 2, and a main drive wheel. A pair of left and right first and second sub-drives disposed on the opposite side (front side in the present embodiment) of the first and second drive wheels 3 (1) and 3 (2) with respect to the vehicle longitudinal direction. It has rings 15 (1) and 15 (2).

  In the present embodiment, the first and second sub drive wheels 15 (1), 15 (2) are steered wheels that are steered in accordance with the operation of the turning operation member 5, and the first and second sub drive wheels 15 (1), 15 (2) The second driving wheels 3 (1) and 3 (2) are non-steering wheels.

Further, as shown in FIG. 2, the wheel-type work vehicle 1 is coaxially disposed in a state of being operatively connected to the first and second sub drive wheels 15 (1) and 15 (2), respectively. The first and second output shafts 16 (1), 16 (2) and the rotational power input operatively from the transaxle 6 are transferred to the first and second output shafts 16 (1), 16 (2). A differential unit 17 capable of transmitting power and an axle unit 19 including a clutch mechanism 18 inserted in a transmission path from the transaxle 6 to the differential unit 17 are provided.
The clutch mechanism 18 can be selectively engaged and disengaged. When the clutch mechanism 18 is engaged, a four-wheel drive state appears, and when the clutch mechanism 18 is released, The driving state is revealed.

Next, the transaxle 6 according to the present embodiment will be described.
FIG. 3 shows an enlarged cross-sectional view of the transaxle 6 in the vicinity of the differential device 23 and the speed increasing device 24.

  As shown in FIGS. 2 and 3, the transaxle 6 is a first coaxially arranged in a state of being operatively connected to the first and second drive wheels 3 (1) and 3 (2), respectively. And the second output shafts 22 (1) and 22 (2) and the rotational power operatively input from the drive source 2 are differentially transmitted to the first and second output shafts 22 (1) and 22 (2). The differential device 23 capable of transmitting, and the speed increase capable of transmitting the rotational power operatively input from the drive source 2 to the first and second output shafts 22 (1), 22 (2) at an increased speed. Device 24.

In the present embodiment, the transaxle 6 includes an axle case 25 that supports the first and second output shafts 22 (1) and 22 (2) and accommodates the differential device 23.
More specifically, the transaxle 6 is the first and second main drive wheels using the rotational power operatively transmitted from the belt type transmission device 14 as the rotational power in the forward direction and the rotational power in the backward direction. The forward / reverse switching device 27 capable of outputting toward the drive wheels 3 (1), 3 (2) (and the first and second sub drive wheels 15 (1), 15 (2)), the first and first Friction-type first and second brake devices 28 (1) and 28 (2) for applying a braking force to the two drive wheels 3 (1) and 3 (2) are provided.

  The first and second output shafts 22 (1) and 22 (2) have first end portions 221 (1) on the side close to the corresponding first and second drive wheels 3 (1) and 3 (2). ), 221 (2) extends outward from the axle case 25, and the second ends 222 (1), 222 (2) on the side close to the differential 23 sandwich the differential 23. The axle case 25 is rotatably supported in the state.

  The differential device 23 has an input gear 41 whose rotational axis is positioned coaxially with the first and second output shafts 22 (1) and 22 (2) and operatively inputs rotational power from the drive source 2. And bevel pinions 43, 43 that revolve with the rotation of the input gear 41 and that can rotate about the axis of the pivot shaft 42 that extends in the radial direction with respect to the rotation axis, and the bevel pinions 43, 43 First and second side bevel gears 44 (1), 44 (2) supported in a relatively non-rotatable manner on the first and second output shafts 22 (1), 22 (2), respectively. A differential lock position in which at least one of the first and second side bevel gears 44 (1) and 44 (2) cannot rotate relative to the input gear 41 around the rotation axis and the at least one side bevel gear 44 (1 (44 (2)) and a differential locking member 61 capable of taking a differential position freely the axis of rotation rotates relative to the input gear 41.

  In the present embodiment, the input gear 41 is an annular gear, and the second ends 222 (1) and 222 (2) of the first and second output shafts 22 (1) and 22 (2). Is engaged with a gear 35 to which the rotational power from the drive source 2 is transmitted. The pivot shaft 42 is provided on the inner side of the input gear 41 so as to extend in the radial direction of the input gear 41.

  More specifically, in the differential device 23, the first and second outputs of the differential device 23 are positioned coaxially with the first and second output shafts 22 (1) and 22 (2) and together with the input gear 41. A differential case 45 that rotates integrally around the rotation axis of the shafts 22 (1) and 22 (2) is provided.

  The differential case 45 is disposed inside the input gear 41 so as to accommodate the pivot shaft 42, the bevel pinions 43, 43, and the first and second side bevel gears 44 (1), 44 (2). The first and second output shafts 22 (1) and 22 (2) are supported by the second end portions 222 (1) and 222 (2) of the first and second output shafts 22 (1) and 22 (2) so as to be relatively rotatable. ing.

  The differential lock member 61 is not rotatable relative to one of the first and second output shafts 22 (1) and 22 (2) (the second output shaft 22 (2) in the illustrated embodiment) and moves in the rotational axis direction. Supported as possible.

  The differential lock member 61 has an engaging portion 61 a that is one of a concave portion and a convex portion on the surface facing the input gear 41. Further, the differential case 45 fixed to the input gear 41 has an engaged portion 45 a that is the other of the concave portion or the convex portion on the surface facing the engaging portion 61 a of the differential lock member 61.

  The engaging portion 61a of the differential lock member 61 is selectively engaged with and disengaged from the engaged portion 45a of the differential case 45 according to the position of the differential lock member 61 in the rotational axis direction. Accordingly, the differential lock member 61 can be connected to the differential case 45, that is, the input gear 41 so as not to be relatively rotatable, according to the position in the rotational axis direction.

  As shown in FIG. 3, when the differential lock member 61 is positioned at a differential lock position where the differential lock member 61 is engaged with the input gear 41 in the rotational axis direction, the differential lock member 61 together with the input gear 41 is the first and The second output shafts 22 (1) and 22 (2) rotate around the rotation axis. Therefore, a diff lock state appears in which the input rotational power is forcibly synchronously transmitted to the first and second drive wheels 3 (1), 3 (2).

  On the other hand, when the differential lock member 61 is positioned at a differential position that is not engaged with the input gear 41 in the rotational axis direction, the differential lock member 61 is rotatable relative to the input gear 41, and Together with the input gear 41, the first and second output shafts 22 (1) and 22 (2) do not rotate around the rotation axis. Therefore, a differential state in which the input rotational power is differentially transmitted according to the traveling load of the first and second drive wheels 3 (1), 3 (2) appears.

Preferably, the differential lock member 61 is configured to be operated by an actuator 65 (see FIG. 4) that is controlled by an electric signal.
In the present embodiment, the actuator 65 is an electric actuator such as an electric motor, and is operatively connected to the differential lock member 61. However, the actuator 65 may be any actuator that can be controlled by an electric signal. For example, an electromagnetic valve and a hydraulic cylinder may be combined.

  In the present embodiment, the differential lock member 61 is configured to be actuated by the actuator 65 in accordance with the operation of the turning operation member 5 and move to the differential position or the differential lock position, as will be described in detail later. However, the present invention is not limited to such a form. That is, the differential lock member 61 may be mechanically operatively connected to the turning operation member 5, or to a differential position or a differential lock position according to an operation of a differential lock operation member disposed in the vicinity of the driver seat 12. You may comprise so that it may move.

  The speed increasing device 24 includes first and second speed increasing transmission paths capable of transmitting the rotational power of the input gear 41 to the first and second output shafts 22 (1) and 22 (2) in a synchronized state. 50 (1), 50 (2). First and second clutches 51 (1) and 51 (2) are inserted in the first and second speed increasing transmission paths 50 (1) and 50 (2), respectively.

  In the present embodiment, the first and second clutches 51 (1) and 51 (2) are known friction multi-plate clutches. However, the first and second clutches 51 (1) and 51 (2) are not limited to the multi-plate clutch, and various clutches such as a dog clutch and a cone clutch can be used.

Preferably, the first and second clutches 51 (1), 51 (2) are electrically operatively connected to the turning operation member 5, and the engagement state thereof can be changed by an electric signal. .
In the present embodiment, each of the first and second clutches 51 (1) and 51 (2) is an electromagnetic clutch. However, the first and second clutches 51 (1) and 51 (2) only need to be able to change the engagement state by an electric signal, and are configured by combining, for example, an electromagnetic valve and a hydraulic clutch. It is also possible.

The first and second clutches 51 (1) and 51 (2) are either in a fully engaged state in which the engaged state is completely engaged or in a released state in which the engaged state is released, or in a completely engaged state. And the release state can be changed in a plurality of stages or steplessly.
In the present embodiment, the first and second clutches 51 (1) and 51 (2) have a plurality of engagement states, that is, 4/4 (fully engaged state), 3/4, and 2/4. And it is comprised so that any intensity | strength of 1/4 may be taken.

  In the present embodiment, the first and second clutches 51 (1), 51 (2) are electrically controlled according to the operation of the turning operation member 5 as will be described in detail later. However, the present invention is not limited to such a form. That is, the first and second clutches 51 (1) and 51 (2) are mechanically connected to the turning operation member 5, and are mechanically engaged according to the operation of the turning operation member 5. It can be configured to change.

  According to the transaxle 6, the first and second clutches 51 (1) and 51 (2) are disengaged and the diff lock member 61 is positioned at the diff lock position, thereby causing the diff lock state to appear. The first and second clutches 51 (1) and 51 (2) are released and the differential lock member 61 is positioned at the differential position, so that the differential state can be revealed. By engaging one of the clutches 51 (1) and 51 (2) and positioning the differential lock member 61 at the differential position, the engaged clutch 51 (1) (51 (2)) side. The driving wheels 3 (1) (3 (2)) are driven to increase in speed according to the speed increasing ratio of the speed increasing transmission path 50 (1) (50 (2)), and the other clutch 51 (2) (51 ( 1)) side drive wheel (2) (3 (1)) can be from rotational power input thereby revealing a forced differential state to be driven decelerated speed only fraction is the acceleration.

  Here, when the rotational speed of the input rotational power (the rotational speed of the input gear 41) is N, as described above, according to the conventional configuration, the rotational speed difference between the pair of first and second drive wheels is N at most. On the other hand, according to the transaxle 6 according to the present embodiment, the speed increasing ratio of the first and second speed increasing transmission paths 50 (1), 50 (2) is appropriately set in the forced differential state. As a result, the rotational speed difference between the first and second drive wheels 3 (1), 3 (2) can be set to a value larger than the N, so that speedy turning can be performed.

  Next, the transaxle 6 according to the present embodiment will be described in detail.

  In the present embodiment, the speed increasing device 24 includes a drive gear 52 that meshes with the input gear 41, a speed increasing drive shaft 53 that cannot be rotated relative to the drive gear 52, and the speed increasing drive shaft. 53, the first and second intermediate gears 54 (1) and 54 (2) supported rotatably relative to the first intermediate gear 54 (1) and the first output shaft 22 (1). A first driven gear 55 (1) that is not relatively rotatable and a second driven gear 55 that is meshed with the second intermediate gear 54 (2) and is not relatively rotatable with the second output shaft 22 (2). (2), the first clutch 51 (1) interposed between the speed increasing drive shaft 53 and the first intermediate gear 54 (1), the speed increasing drive shaft 53 and the second intermediate gear. 54 (2) and the second clutch 51 (2) interposed therebetween.

The drive gear 52, the speed increasing drive shaft 53, the first intermediate gear 54 (1), and the first driven gear 55 (1) together with the first clutch 51 (1) are the first speed increasing transmission path 50. (1) is formed.
The drive gear 52, the speed increasing drive shaft 53, the second intermediate gear 54 (2), and the second driven gear 55 (2) are connected to the second speed increasing transmission path 50 together with the second clutch 51 (2). (2) is formed.

  The gear ratio between the input gear 41 and the drive gear 52, and the gear ratio between the first intermediate gear 54 (1) and the first driven gear 55 (1) (the second intermediate gear 54 (2) and the first gear). As for the setting of the second driven gear 55 (2), the first driven gear 55 (1) (the second driven gear 55 (2)) is increased with respect to the rotational speed of the input gear 41. Various settings can be taken as long as possible.

  In the present embodiment, the first and second speed increasing transmission paths 50 (1) and 50 (2) correspond to the first and second intermediate gears 54 (1) and 54 (2), respectively. When the first and second driven gears 55 (1) and 55 (2) have the same diameter, the drive gear 52 has a smaller diameter than the input gear 41, thereby rotating the input gear 41. Power is transmitted to the first and second output shafts 22 (1) and 22 (2) so as to be transmitted at an increased speed.

  The first and second speed increasing transmission paths 50 (1) and 50 (2) have the first and second intermediate gears 54 (with the input gear 41 and the drive gear 52 having the same diameter. The first and second driven gears 55 (1) and 55 (2) corresponding to the first and second driven gears 55 (1) and 55 (2) are made smaller in diameter than the first and second driven gears 55 (2), respectively. The two output shafts 22 (1) and 22 (2) can be configured to be able to transmit increased speed.

Various speed increasing ratios of the first and second output shafts 22 (1) and 22 (2) with respect to the rotation of the input gear 41 can be set.
In the present embodiment, the first and second speed increasing transmission paths 50 (1) and 50 (2) are the first and second speed increasing paths when the rotational speed of the input gear 41 is N as described above. The number of rotations of the two output shafts is 2 × N. In other words, the speed increasing ratio of the first and second speed increasing transmission paths 50 (1), 50 (2) is set to double. However, the speed increasing ratio is not limited to 2 times, and can be set arbitrarily (for example, 3 times).

Next, a configuration for operating the first and second clutches 51 (1), 51 (2) and the differential lock member 61 according to the operation of the turning operation member 5 will be described.
FIG. 4 shows a control block diagram of the wheeled working vehicle 1.

  In the present embodiment, the wheeled work vehicle 1 includes a control device 70, a turning sensor 71 that detects an operation state of the turning operation member 5, and a mode switching member 73.

  The control device 70 releases the first and second clutches 51 (1), 51 (2) and positions the differential lock member 61 at the differential position in response to an artificial operation on the mode switching member 73. A normal differential mode, a differential lock mode in which the first and second clutches 51 (1) and 51 (2) are released, and the differential lock member 61 is positioned at a differential lock position, and a forced differential mode are selectively displayed. It is configured as follows.

  In the present embodiment, specifically, the control device 70 includes a calculation unit (hereinafter referred to as a CPU) including control calculation means for executing calculation processing based on a signal input from a sensor such as the turning sensor 71. ROM that stores control programs and control data, setting values, etc. are saved in a state where they are not lost even when the power is turned off, and the setting values etc. can be rewritten and generated during calculation by the calculation unit And a storage unit including a RAM or the like that temporarily holds data.

  When a rotation angle sensor is used as the turning sensor 71, the control device 70 stores the rectilinear operation position of the turning operation member 5 as an initial value, and the turning operation member based on the initial value. By accumulating the operation direction and the operation angle every time the 5 is operated, the operation position (operation state) of the turning operation member 5 at that time can be recognized.

  The mode switching member 73 is configured to be manually operable so that a differential mode position, a differential lock mode position, and a forced differential mode position can be selectively taken. The mode switching member 73 is, for example, a lever disposed in the vicinity of the driver's seat 12 as shown in FIG.

  In the present embodiment, the wheeled work vehicle 1 includes a mode switching position detection sensor 75 that detects the operation position of the mode switching member 73, and the control device 70 selects a mode from the mode switching position detection sensor 75. A mode selected based on the signal is displayed.

  When the normal differential mode is selected by the mode switching member 73, the control device 70 releases the first and second clutches 51 (1), 51 (2) and the differential lock member 61 is in the differential state. The actuator 65 is operated so as to be positioned. Thereby, the differential state can be made to appear.

  When the diff lock mode is selected by the mode switching member 73, the control device 70 releases the first and second clutches 51 (1) and 51 (2) and the diff lock member 61 is in the diff lock position. The actuator 65 is operated so as to be located at the position. Thereby, the differential lock state can be revealed.

  When the forced differential mode is selected by the mode switching member 73, the control device 70 operates the actuator 65 so that the differential lock member 61 is positioned at the differential position, and outputs a signal from the turning sensor 71. Based on this, both the clutches 51 (1) and 51 (2) are operated so that the both clutches 51 (1) and 51 (2) are released when traveling straight, and one of the clutches 51 located inside the corner when turning. (1) Both clutches 51 (1), 51 (51) (51 (2)) are disengaged and the other clutch 1 (2) (51 (1)) located on the outside of the turn is engaged. Operate 2).

  As a result, when the forced differential mode is selected, the driving wheels 3 (1) (3 (2)) on the side of the other clutch 51 (2) (51 (1)) that is engaged with the speed increasing transmission path 50 (1 ) (51 (2)), the driving wheel 3 (2) () on the side of the one clutch 51 (1) (51 (2)) that has been driven to increase in accordance with the speed increasing ratio of 51 (2) and released. 3 (1)) can be made to appear in a forced differential state in which it is decelerated by the increased speed from the rotational power input.

  Specifically, in the present embodiment, the strength of the engaged state of the first and second clutches 51 (1) and 51 (2) can take a plurality of stages according to the operation amount of the turning operation member 5. When the turning operation member 5 is operated to the substantially maximum turning operation position, the strength of the engaged state is in the fully engaged state, and the turning operation member 5 is moved to the straight operation position and the substantially maximum turning operation position. When operated between the turning operation positions, the strength of the engagement state gradually decreases as the operation angle of the turning operation member 5 decreases from the state of the substantially maximum turning operation position.

  That is, when the turning operation member 5 is operated within a range less than the first predetermined operation amount from the straight operation position, the one clutch 51 (1) (51 (2)) located inside the turning is released. However, the other clutch 51 (2) (51 (1)) located on the outer side of the turn is engaged so that the strength of the engaged state becomes 1/4, for example.

  When the turning operation member 5 is operated within the range not less than the first predetermined operation amount and less than the second predetermined operation amount, the one clutch 51 (1) (51 (2)) remains in the released state. The other clutch 51 (2) (51 (1)) is operated so that the strength of the engaged state is, for example, 2/4. Thus, the strength of the engaged state is increased from 1/4 to 2/4.

  When the turning operation member 5 is operated within the range of the second predetermined operation amount or more and less than the third predetermined operation amount, the one clutch 51 (1) (51 (2)) remains in the released state. The other clutch 51 (2) (51 (1)) is operated so that the strength of the engaged state is, for example, 3/4. Thus, the strength of the engaged state is further increased from 2/4 to 3/4.

  When the turning operation member 5 is operated within the range of the third predetermined operation amount or more and within the maximum operation amount (up to the substantially maximum turning operation position), the one clutch 51 (1) (51 (2)) is operated. The other clutch 51 (2) (51 (1)) operates so that the strength of the engaged state becomes 4/4 (completely engaged state) while being in the released state. Thus, the strength of the engaged state is increased to the maximum.

  As a result, as described above, in the present embodiment, the speed increasing ratio of the first and second speed increasing transmission paths 50 (1), 50 (2) is set to double, so that the turning operation is performed. When the member 5 is operated within a range less than the first predetermined operation amount from the straight operation position, the other output shaft 22 (2) positioned on the turning outer side with respect to the rotation speed N of the input gear 41. The drive rotational speed of (22 (1)) is increased to 5N / 4, and the drive rotational speed of the one output shaft 22 (1) (22 (2)) located inside the turning is accordingly 3N / 4. To decrease.

  When the turning operation member 5 is operated within the range not less than the first predetermined operation amount and less than the second predetermined operation amount, the other output shaft 22 (with respect to the rotational speed N of the input gear 41). 2) The drive rotational speed of (22 (1)) increases to 6N / 4, and the drive rotational speed of the one output shaft 22 (1) (22 (2)) decreases to 2N / 4 accordingly. .

  When the turning operation member 5 is operated within the range not less than the second predetermined operation amount and less than the third predetermined operation amount, the other output shaft 22 (with respect to the rotation speed N of the input gear 41). 2) The drive rotational speed of (22 (1)) increases to 7N / 4, and the drive rotational speed of the one output shaft 22 (1) (22 (2)) decreases to N / 4 accordingly. .

  When the turning operation member 5 is operated within the range not less than the third predetermined operation amount and within the maximum operation amount, the other output shaft 22 (2) ( 22 (1)) increases to 2N, and the output speed of the one output shaft 22 (1) (22 (2)) becomes zero.

  In the present embodiment, at the time of turning, the control device 70 determines the strength of the engaged state of the clutch 51 (2) (51 (1)) engaged as the operation amount of the turning operation member 5 increases. However, the present invention is not limited to such a form. That is, the control device 70 can be configured such that the engagement state of the clutch 51 (2) (51 (1)) engaged is steplessly increased as the operation amount of the turning operation member 5 increases. .

  The transaxle 6 according to the present embodiment includes the first and second drive wheels 3 (1) and 3 (2) which are main drive wheels that cannot be steered on one side with respect to the vehicle longitudinal direction. Although applied to the wheeled working vehicle 1 having the sub drive wheels 15 (1) and 15 (2) as steering wheels on the other side with respect to the vehicle longitudinal direction, the present invention is limited to such a configuration. is not. That is, a working vehicle having a pair of left and right drive wheels that cannot be steered on one side with respect to the longitudinal direction of the vehicle and a non-driving wheel on the other side with respect to the longitudinal direction of the vehicle and a wheel (caster wheel) that is rotatable about a vertical axis. It is also possible to apply. In this case, the turning radius is determined by a change in strength of the engaged state of the first and second clutches 51 (1) and 51 (2).

  Here, an assembly structure of the speed increasing device 24 in the transaxle 6 will be described.

  In the present embodiment, the axle case 25 of the transaxle 6 supports the first and second output shafts 22 (1) and 22 (2) and houses the differential device 23 as described above. . The axle case 25 is formed with an opening 251 that allows external access to the input gear 41, the first driven gear 55 (1), and the second driven gear 55 (2). Preferably, the opening 251 is disposed so as to face the vehicle front-rear direction.

  On the other hand, the drive gear 52, the speed increasing drive shaft 53, the first and second clutches 51 (1), 51 (2) and the first and second intermediate gears 54 (1), 54 (2) are assembled. The unit 80 is formed.

  In the unit 80, the drive gear 52, the first intermediate gear, and the second intermediate gears 54 (1) and 54 (2) are respectively connected to the input gear 41 and the first driven gear 55 through the opening 251. (1) and the second driven gear 55 (2) are detachably connected to the axle case 25 so as to mesh with the second driven gear 55 (2).

According to such a configuration, the unit 80 can be easily assembled to the axle case 25 when the speed increasing device 24 is assembled to the transaxle 6.
In addition, it is possible to easily cope with a change in the specifications of the transaxle (that is, a change that omits the function of the speed increasing device 24) by attaching and detaching the unit 80. When the unit 80 is removed from the axle case 25, a lid member is detachably connected to the axle case 25 so as to cover the opening 251 instead of the unit 80.

More specifically, in the present embodiment, the speed increasing device 24 includes the drive gear 52, the speed increasing drive shaft 53, the first and second clutches 51 (1), 51 (2), and the first. And a speed increasing case 57 covering the second intermediate gears 54 (1), 54 (2).
The speed increasing case 57 is included in the unit 80 and has an opening 571 in which the drive gear 52 and the first and second intermediate gears 54 (1) and 54 (2) face the outside.

  In the unit 80, the opening 571 of the speed increasing case 57 overlaps the opening 251 of the axle case 25, and the drive gear 52, the first intermediate gear 54 (1), and the second intermediate gear 54 ( 2) is detachably connected to the axle case 25 by a fastening member such as a bolt so that the input gear 41, the first driven gear 55 (1), and the second driven gear 55 (2) are engaged with each other. ing.

DESCRIPTION OF SYMBOLS 1 Wheel type work vehicle 2 Drive source 3 (1) 1st drive wheel 3 (2) 2nd drive wheel 5 Turning operation member 6 Transaxle 22 (1) 1st output shaft 22 (2) 2nd output shaft 23 Differential Device 24 Speed increaser 25 Axle case 41 Input gear 43 Bevel pinion 44 (1) First side bevel gear 44 (2) Second side bevel gear 50 (1) First speed increase transmission path 50 (2) Second speed increase transmission path 51 (1) First multi-plate clutch 51 (2) Second multi-plate clutch 52 Drive gear 53 Speed increasing drive shaft 54 (1) First intermediate gear 54 (2) Second intermediate gear 55 (1) First driven gear 55 (2) Second driven gear 61 Differential lock member 65 Actuator 70 Controller 71 Turning sensor 73 Mode switching member 80 Unit 251 Opening

Claims (5)

A transaxle that transmits rotational power operatively transmitted from a drive source to a pair of left and right first and second drive wheels;
First and second output shafts arranged coaxially in a state of being operatively connected to the first and second drive wheels, respectively, and rotational power operatively input from the drive source, A differential device capable of differentially transmitting to the two output shafts, and a speed increasing device capable of transmitting the rotational power operatively input from the drive source to the first and second output shafts.
The differential device includes an input gear having a rotational axis coaxially positioned with the first and second output shafts and operatively receiving rotational power from the drive source, and revolving as the input gear rotates. A bevel pinion that can rotate about a pivot axis that extends in a radial direction with respect to the rotation axis, and a first and second output shaft that are engaged with the bevel pinion so as not to rotate relative to each other. A differential lock position where at least one of the first and second side bevel gears and the first and second side bevel gears cannot rotate relative to the input gear around the rotation axis and the side bevel gear with respect to the input gear. A differential lock member capable of taking a differential position that is relatively rotatable about the rotation axis,
The speed increasing device includes first and second speed increasing transmission paths capable of transmitting the rotational power of the input gear to the first and second output shafts in a synchronized state, and the first and second speed increasing paths. A transaxle characterized in that first and second clutches are respectively inserted in the high-speed transmission paths.   The transaxle according to claim 1, wherein the first and second clutches are multi-plate clutches. An axle case that supports the first and second output shafts and accommodates the differential;
The speed increasing device includes: a driving gear meshing with the input gear; a speed increasing driving shaft that is not rotatable relative to the driving gear; and a first speed gear supported by the speed increasing driving shaft so as to be relatively rotatable. A second intermediate gear, a first driven gear meshed with the first intermediate gear and made non-rotatable relative to the first output shaft, and meshed with the second intermediate gear and relatively rotated around the second output shaft The second driven gear disabled, the first clutch inserted between the speed increasing drive shaft and the first intermediate gear, and the power driven drive shaft and the second intermediate gear. And the second clutch
The axle case has an opening that allows external access to the input gear, the first driven gear, and the second driven gear;
The drive gear, the speed increasing drive shaft, the first and second clutches, and the first and second intermediate gears form a unit;
The axle case is configured so that the drive gear, the first intermediate gear, and the second intermediate gear mesh with the input gear, the first driven gear, and the second driven gear, respectively, through the opening. The transaxle according to claim 1 or 2, wherein the transaxle is detachably connected to the transaxle. A drive source, a pair of left and right first and second drive wheels, a turning operation member, and a transaxle that transmits rotational power operatively input from the drive source to the first and second drive wheels; A wheel type working vehicle comprising a control device and a mode switching member,
The transaxle has first and second output shafts arranged coaxially in a state in which the transaxle is operatively connected to the first and second drive wheels, respectively, and rotational power operatively input from the drive source. A differential device capable of differentially transmitting to the first and second output shafts; and a speed increasing device capable of transmitting the rotational power operatively input from the drive source to the first and second output shafts. With
The differential device includes an input gear having a rotational axis coaxially positioned with the first and second output shafts and operatively receiving rotational power from the drive source, and revolving as the input gear rotates. A bevel pinion that can rotate about a pivot axis that extends in the radial direction with respect to the rotation axis, and a first and second output shaft that are engaged with the bevel pinion so as not to rotate relative to each other. A differential lock position in which at least one of the first and second side bevel gears and the first and second side bevel gears cannot rotate relative to the input gear around the rotation axis and the at least one side bevel gear are the input gear. A differential lock member capable of taking a differential position that is rotatable relative to the rotation axis with respect to the rotation axis,
The speed increasing device includes first and second speed increasing transmission paths capable of transmitting the rotational power of the input gear to the first and second output shafts in a synchronized state, and the first and second speed increasing paths. The first and second clutches are inserted in the fast transmission path, respectively.
The differential lock member is actuated by an actuator that is actuated and controlled by an electrical signal;
The engagement state of the first and second clutches is changed by an electric signal,
The control device includes: a normal differential mode in which the first and second clutches are disengaged and the differential lock member is positioned at a differential position in response to an artificial operation on the mode switching member; and the first and second clutches The differential lock mode in which the differential lock member is placed in the unlocked state and the differential lock member is positioned at the differential lock position, and the forced differential mode are selectively revealed.
In the forced differential mode, the control device places the differential lock member in the differential position, and based on a signal from a turning sensor that detects an operation state of the turning operation member, sets both clutches in a released state when traveling straight. A wheel-type working vehicle characterized in that one of the clutches located on the inner side of the turn is released during turning and the other clutch located on the outer side of the turn is in an engaged state according to the operation amount of the turning operation member. .   The first and second speed increasing transmission paths are configured such that when the rotational speed of the input gear is N, the rotational speed of the first and second output shafts is 2 × N. The wheel type working vehicle according to claim 4.

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