JP2007297050A - Steering structure for working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering structure with an excellent steering property capable of performing turning of a machine body according to operation of a steering operation unit and arbitrarily turning a smaller circle only when required. <P>SOLUTION: In the steering structure for the working machine constituted such that the machine body is turned in response to a direction that the steering operation unit 72 is operated by giving speed difference to right and left crawler traveling devices by operating the steering operation unit 72, a speed ratio of the right and left crawler traveling devices 1 provided with a reset type turning mode change operation unit 75 and set according to an operation amount in a right/left direction of the steering operation unit 72 only when the turning mode change operation unit 75 is operated is changed to make it to a turning mode for enhancing turning function. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a steering structure for a work machine such as a combine machine configured to travel with left and right crawler travel devices.

As the steering structure, for example, as disclosed in Patent Document 1, by operating the steering operation tool left and right, a speed difference is given to the left and right crawler travel devices, and the direction in which the steering operation tool is operated A structure is proposed in which the airframe is swiveled and the turning function set by the steering operation tool can be selected and changed by a turning mode selection switch.
JP 2001-191941 A

  In the proposed structure, a side clutch is interposed in each of the transmission systems to the left and right crawler traveling devices, and the crawler traveling device with the side clutch disengaged is connected to the deceleration transmission portion or the brake via a friction clutch to interlock the steering. Since the structure that reduces or stops the speed of the crawler traveling device inside the turn by adjusting the degree of handing of the friction clutch according to the operation amount of the operation tool, slip is caused in the friction clutch depending on the load. Occurred, and the turning function may change even when the operation amount of the steering operation tool is the same.

  In addition, the turning mode selection switch can perform a turning operation from a turning operation for decelerating one of the crawler traveling devices on the inside of the turning to a trusty turning for braking one of the crawler traveling devices on the inside of the turning with a brake. The selected turning mode is sufficiently recognized because either the mode or the second turning mode that performs only the turning operation that decelerates one of the crawler traveling devices inside the turning is selected by the turning mode selection switch. Therefore, it is desirable to have a monitoring means such as a lamp for displaying the selected turning mode.

  The present invention has been made paying attention to such points, and can turn the body according to the operation of the steering operation tool, and can optionally make a smaller turn only when necessary. The main purpose is to provide a steering structure with excellent operability.

〔Constitution〕
According to a first aspect of the present invention, there is provided a working machine configured to give a speed difference to the left and right crawler travel devices by operating a steering operation tool, and to turn the machine body according to a direction in which the steering operation tool is operated. A steering structure,
A return-type turning mode change operation tool is provided, and the speed ratio of the left and right crawler travel devices set according to the operation amount of the steering operation tool is changed only while the turning mode change operation tool is operated. The present invention is characterized in that it is configured to be in a turning mode that enhances the turning function.

[Action]
According to the above configuration, by operating the steering operation tool without touching the turning mode change operation tool during normal turning, the aircraft can be steered according to the steering operation direction, and the turning mode is changed during the turning. When the operating tool is operated, the turning function is enhanced and a small turn is performed only while the turning mode change operating tool is operated. Then, when the finger is released from the turning mode changing operation tool, the original turning mode is restored, and a relatively gentle body turning according to the operation of the steering operation tool is performed.

〔The invention's effect〕
Therefore, according to the first aspect of the present invention, it is possible to normally perform a relatively gentle body turn according to the operation of the steering operation tool, and to operate the turning mode change operation tool with a consciousness. The turning can be performed only when necessary, and the desired aircraft can be steered appropriately without any mistakes.

〔Constitution〕
According to a second aspect of the present invention, in the first aspect of the invention, the left and right crawler travel devices are independently driven to shift right and left by a hydraulic continuously variable transmission capable of continuously variable transmission over a forward range and a reverse range. Thus, the continuously variable transmission of one of the crawler travel devices on the inside of the turn is configured to be controlled in the deceleration direction by operating the steering operation tool.

[Action]
According to the above configuration, when the steering operation tool is operated to the left or right, the continuously variable transmission of one of the crawler traveling devices is decelerated, and the aircraft turns in the direction in which the steering operation tool is operated. As the operation amount increases, one of the continuously variable transmission is decelerated greatly, and the turning becomes smaller. Finally, one continuously variable transmission is decelerated to neutrality, one crawler traveling device is stopped, and only the other crawler traveling device is driven to perform a pivot. Further, when the steering operation tool is steered greatly, one continuously variable transmission is driven in the reverse direction beyond the neutral position, and a sudden turn is performed by a super turn.

  Moreover, by operating the turning mode changing operation tool in the middle of the steering of the airframe by the steering operation tool, the turning function is changed to the high mode as described above, and it is possible to perform a smaller turn.

〔The invention's effect〕
Therefore, according to the second aspect of the invention, it is possible to perform a wide range from a gentle turn to a super turn, and a steering with a high turning function can be performed temporarily and at any time. And the steering performance can be further improved.

〔Constitution〕
According to a third aspect of the present invention, in the second aspect of the invention, in the turning mode in which only the steering operation tool is operated, the speed ratio is changed within a range in which the left and right crawler travel devices are driven in the same direction. In the turning mode in which the change operation tool is operated, the continuously variable transmission on the side to be decelerated is set so as to be capable of shifting to the reverse rotation range beyond neutrality.

[Action]
According to the above configuration, in the turning mode in which only the operation of the steering operation tool is operated, the left and right crawler traveling devices are driven in the same direction and can turn in a relatively gentle range in which a speed difference is given. In the turning mode in which the turning mode change operation tool is operated, by operating the steering operation tool greatly, the turning of the continuously variable transmission on the side to be decelerated is stopped and the super turning of the reverse rotation is performed. Can be done.

〔The invention's effect〕
Therefore, according to the third aspect of the present invention, it is possible to make a relatively gentle turn of the vehicle usually by operating only the steering operation tool, and consciously abruptly by simultaneous operation of the steering operation tool and the turning mode change operation tool. It is possible to perform turning and to perform steering accurately with little risk of erroneous operation.

〔Constitution〕
The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the turning mode change operation tool is configured as a return-type push button, and the turning function is performed when the push button is not pushed. A low turning mode is set, and a turning mode having a high turning function is set in a state where the turning mode is pushed.

[Action]
According to the above configuration, the mode is changed to a mode with a high turning function by simply pressing the return-type push button with a finger, and when the finger is released from the push button, the mode returns to the original mode. So-called inching steering, in which the aircraft is steered little by little, becomes easy.

〔The invention's effect〕
Therefore, according to the invention of claim 4, the turning mode changing operation can be performed quickly and arbitrarily, and the operability is excellent.

〔Constitution〕
According to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, the operation amount of the turning mode changing operation tool is configured to be detectable, and the turning function is higher as the detected operation amount is larger. The turning mode is set.

[Action]
According to the above configuration, when the turning mode changing operation tool is changed to the turning mode in which the turning can be turned by finger operation, the turning function becomes higher as the turning mode changing operation tool is operated more greatly, and the turning in a smaller direction is performed. It will be.

〔The invention's effect〕
Therefore, according to the fifth aspect of the invention, it is possible to freely combine a standard steering operation by the steering operation tool and a delicate small turning by a finger operation of the turning mode change operation tool. It can be performed.

  FIG. 1 shows an entire side surface of a self-removing combine that is an example of a working machine according to the present invention. The basic structure of this combine is not particularly different from the conventional one, and a multi-cutting mowing operation unit 3 is driven ascending and descending as a harvesting operation unit at the front of a traveling machine body 2 equipped with left and right crawler traveling devices 1. In addition to being connected to each other, on the right side of the front part of the traveling machine body 2, there is provided a control unit 6 in which an engine 5 is installed below the driver seat 4, and on the upper left side of the traveling machine body 2 is a threshing device 7. It is mounted and has a structure in which a grain recovery tank 9 provided with a screw type unloader 8 is arranged on the right side. The mowing operation unit 3 includes a plurality of pulling device 11, a clipper type mowing device 12, and a mowing cereal basket on a mowing working unit frame 10 supported on the front portion of the traveling machine body 2 so as to swing up and down around a fulcrum X. Is provided with a cereal conveying device 14 that conveys the raw material toward the feed chain 13 of the threshing device 7, and the entire mowing operation unit 3 is driven up and down by a hydraulic cylinder 15.

  The present invention is characterized by the transmission structure to the crawler traveling device 1 and the mowing unit 3, and the following detailed configuration will be described based on the drawings.

  FIG. 2 is a schematic configuration diagram of the transmission structure as viewed from the front of the machine body, and FIG. 3 is a longitudinal front view of the mission case 20. In these figures, a pair of hydraulic continuously variable transmissions (HSTs) 21 for independently driving the left and right crawler travel devices 1 are provided on one lateral side of the transmission case 20 (the right lateral side with respect to the aircraft). 22 and a hydraulic continuously variable transmission (HST) 23 that drives the cutting work unit 3. Further, an input shaft 24 projects from the other lateral surface of the mission case 20 (the left lateral surface with respect to the aircraft), and the input shaft 24 and the engine 5 are interlocked with a belt.

  Each of the continuously variable transmissions 21, 22, and 23 has axial plunger type variable displacement pumps P (1), P (2), and P (3) in a casing part integrally projecting from the right side wall of the transmission case 20, respectively. And constant capacity type motors M (1), M (2), M (3) are installed, and port blocks 21c, 22c, 23c for hydraulic control are attached to the outer end of the case. The power that has entered the shaft 24 is transmitted from the counter gear G1 to the pump shafts 21a and 22a of the continuously variable transmissions 21 and 22 of the traveling system via the gears G2 and G3, and is also transmitted to the working system via the gear G4. It is transmitted to the pump shaft 23a of the continuously variable transmission 23. Each motor shaft 21b is operated by changing the swash plate angle of each variable displacement pump P (1), P (2), P (3) and changing the discharge direction and discharge amount of the pressure oil. , 22b and 23b can be switched between forward and reverse rotations and continuously variable from zero speed.

  The speed change output from the motor shaft 21b of the continuously variable transmission 21 is transmitted to the first intermediate shaft (left) 26 via the gear-type sub-transmission mechanism (left) 25 and then to the second intermediate shaft 27. The left crawler traveling device 1 is driven by being transmitted to the axle (left) 29 via the gear reduction mechanism 28 that is loosely supported. Further, the shift output from the motor shaft 22 b of the continuously variable transmission 22 is transmitted to the first intermediate shaft (right) 31 via the gear-type sub-transmission mechanism (right) 30 and then to the second intermediate shaft 27. The right crawler traveling device 1 is driven by being transmitted to the axle (right) 33 through the loosely supported gear reduction mechanism 32.

  The auxiliary transmission mechanism (left) 25 is a pair of gears loosely fitted to the large and small gears G5, G6 and the first intermediate shaft (left) 26 driven by the motor shaft 21b and meshed with the gears G5, G6. G7, G8, a transmission boss 35 splined to the first intermediate shaft (left) 26 between both gears G7, G8, and a shift sleeve 36 externally fitted to the transmission boss 35 are provided in a constant mesh format. The shift sleeve 36 is configured so as to be capable of shifting in two steps of high and low, and the shift sleeve 36 is shifted so as to mesh between the transmission boss 35 and the boss of the gear G8, whereby "low speed" is obtained. “High speed” is obtained by shifting so as to mesh over the boss of G7, and when the shift sleeve 36 is positioned on the transmission boss 35 and the engagement with the bosses of both gears G7 and G8 is released, Thereby making it possible to bring the neutral ".

  The auxiliary transmission mechanism (right) 30 is also configured to have the same specifications as the auxiliary transmission mechanism (left) 25, and has large and small gears G9 and G10 driven by a motor shaft 22b and a first intermediate shaft (right) 31. A pair of gears G11, G12 engaged with the gears G9, G10, a transmission boss 37 splined to the first intermediate shaft (right) 31 between the gears G11, G12, and a transmission The shift sleeve 38 is externally fitted to the boss 37 by a spline. By shifting the shift sleeve 38 so as to engage the transmission boss 37 and the boss of the gear G12, "low speed" is obtained. “High speed” is obtained by shifting so as to mesh between the transmission boss 37 and the boss of the gear G11, and the shift sleeve 38 is positioned on the transmission boss 37 so that the bosses of both the gears G11 and G12 are engaged. Solution If you divide, you can bring "neutral".

  As shown in FIG. 4, the pair of shift forks 40 and 41 engaged with the shift sleeves 36 and 38 of the both sub-transmission mechanisms 25 and 30 have a common shift shaft supported by the transmission case 20 so as to be movable left and right. The shift shaft 42 is configured to be driven and shifted by a speed change operation cylinder 43 assembled to the transmission case 20, and the shift shaft 42 is selectively moved to three positions by the speed change operation cylinder 43. Thus, both the sub-transmission mechanisms 25 and 30 are switched to “low speed” for work travel, “high speed” for mobile travel, or “neutral”.

  A piston rod 44 connected to the shift shaft 42 and a ring-shaped piston 45 fitted and supported by the shift shaft 42 are incorporated in the speed change operation cylinder 43, and the piston rod is moved to three positions by controlling the pressure oil supply pattern. It is possible to move out and in. That is, as shown in FIG. 7, the speed change operation cylinder 43 is connected to a pair of electromagnetic opening and closing valves 46 and 47, and the switch mechanism SW that detects the operation position of the auxiliary speed change lever 48 provided in the control unit 6. Based on the detection result, switching control is performed as follows.

  That is, when the auxiliary transmission lever 48 is in the neutral position, as shown in FIG. 7 (a), both the electromagnetic opening / closing valves 46, 47 are in a non-excited state, and both the electromagnetic opening / closing valves 46, 47 are both opened. Thus, pressure is applied to the two pressure oil ports a and b of the speed change operation cylinder 43, and the piston rod 44 is retreated in the left direction in the figure by the pressure from the pressure oil port a. The piston rod 44 is moved to the limit in the right direction in the figure by the pressure from the pressure oil port b, and the piston rod 44 is held at the neutral position restricted by the ring-shaped piston 45 due to the difference in pressure receiving area. When the auxiliary transmission lever 48 is operated to the “low speed” position, as shown in FIG. 7 (b), only one electromagnetic opening / closing valve 47 is energized and the pressure oil port a is communicated with the tank. The piston rod 44 and the ring-shaped piston 45 are moved to the limit in the right direction in the figure by the pressure from the oil port b, and the piston rod 44 is advanced to the “low speed” for working travel. Further, when the auxiliary transmission lever 48 is operated to the “high speed” position, as shown in FIG. 7C, only one of the electromagnetic on-off valves 46 is energized and excited, and the pressure oil port b is communicated with the tank. The piston rod 44 is moved to the limit in the left direction in the figure by the pressure from the oil port a, and the piston rod 44 is retracted to the “high speed” for moving travel.

  The first intermediate shaft (left) 26 is supported over the left and right side walls of the transmission case 20, while the first intermediate shaft (right) 31 is loosely supported by the first intermediate shaft (left) 26. In addition, a multi-plate linear clutch 50 that is hydraulically operated is interposed between the first intermediate shaft (left) 26 and the first intermediate shaft (right) 31. The straight clutch 50 is engaged when the left traveling continuously variable transmission 21 and the right traveling continuously variable transmission 22 are both operated in the same direction in the same direction, that is, in the straight operation state, the clutch is engaged. Even if the first intermediate shaft (left) 26 and the first intermediate shaft (right) 31 are integrated and the output rotational speeds of both continuously variable transmissions 21 and 22 are slightly different, the axle (left) 29 and the axle (Right) 33 is driven at the same speed, and a straight traveling state is surely brought about. Further, when the operation of the continuously variable transmission 21 for the left traveling and the continuously variable transmission 22 for the right traveling is not the same, that is, when the steering operation of the fuselage is performed, the linear clutch 50 is operated to be disconnected. In addition, the linear clutch 50 is controlled to operate in conjunction with the steering operation.

  As shown in FIG. 4, the linear clutch 50 includes a large-diameter drum 51 fixed to the first intermediate shaft (left) 26 and a small-diameter drum 52 fixed to the end portion of the first intermediate shaft (right) 31. Pressure oil supplied through oil passages c and d in the shaft is provided with a friction plate 53 interposed therebetween and a piston member 54 incorporated between the first intermediate shaft (left) 26 and the large-diameter drum 51. The clutch engaging / disengaging operation is configured to be engaged or disengaged by forward or reverse operation of the clutch, and the clutch engaging operation oil passage c and the clutch disengaging operation oil passage d are electromagnetically connected via a rotary joint 55 attached to the shaft end. The on-off valves 56 and 57 are connected to [see FIG. 7].

  Further, an inwardly expanding brake 58 is mounted on the end portion of the first intermediate shaft (left) 26, and a ring-shaped spring 59 that presses and urges the piston member 54 in the clutch engagement direction is attached to the linearly-moving clutch 50. In a state in which a plurality of sheets are assembled and no pressure is applied to any of the oil passages c and d, the friction plate 53 is elastically pressed by the spring 59 and the linear clutch 50 is lightly connected. Has come to be brought.

  Accordingly, when switching from the straight traveling state to the turning state, or when returning from the turning state to the straight traveling state, a state in which no pressure is generated in both the oil passages c and d is revealed for a very short time. 29 and 33 are brought into a lightly connected state via the straight clutch 50, and the occurrence of a shock at the start of turning and a shock when returning from turning to straight running is suppressed.

  When the aircraft is parked, the engine 5 is stopped and the brake 58 is applied. However, when the engine 5 is stopped, the oil passages c and d are not pressurized, so the piston member 54 is free. As a result, the straight clutch 50 is disengaged and the brake 58 acts only on the first intermediate shaft (left) 26 and only the left crawler traveling device 1 is braked. Since the first intermediate shaft (left) 26 and the first intermediate shaft (right) 31 are in an appropriate frictional transmission state via the spring 59, the braking action acting on the first intermediate shaft (left) 26 is the first intermediate shaft. (Right) 31 also extends to some extent, and even when parked on a slope, it is avoided that the crawler traveling device 1 on the right side is in a free state and the aircraft is steered by its own weight. It is like that.

  As shown in FIGS. 2 and 3, the shift output from the motor shaft 23 b of the continuously variable transmission 23 of the work system is a work output shaft (PTO shaft) protruding from the left lateral surface of the transmission case 20. 60 is transmitted through gears G12 and G13, and is transmitted to the mowing unit 3 via a belt tension type mowing clutch (not shown).

  FIG. 6 shows a hydraulic circuit relating to the continuously variable transmissions 21, 22, and 23. The variable displacement pumps P (1) and P (2) of the continuously variable transmissions 21 and 22 in the traveling system are shifted by servo cylinders 63 and 64 that are controlled by the valve units 61 and 62, respectively. Yes. Each valve unit 61, 62 is configured by combining a pair of normally closed type electromagnetic on-off valves 65, 66 and a pair of normally open type electromagnetic on-off valves 67, 68. As shown in FIG. Both valve units 61 and 6 are connected to a control device 70 and controlled as described later.

A charge pump CP (1) for supplying charge pressure oil to the charge circuits e and f of both continuously variable transmissions 21 and 22 is mounted on the pump shaft 22a of one continuously variable transmission 22 of the traveling system. Pump shaft 23 in the continuously variable transmission 23 of the working system
At a, a charge pump CP (2) that supplies charge pressure oil only to the charge circuit g of the continuously variable transmission 23 is mounted. Here, the pressure oil from the charge pump CP (1) is also supplied to valve units 61 and 62 for shifting the traveling continuously variable transmissions 21 and 22, that is, a hydraulic servo system to which a load is applied. For this reason, the charge pump CP (1) has a larger discharge amount than the charge pump CP (2), and the charge relief valves CR (1) and CR (2) are used for the charge circuit e, The pressure of f is set to be higher than the pressure of the charge circuit g in the work system.

  Further, the casings of the traveling continuously variable transmissions 21 and 22 are connected to each other by a pipe h in the case, and the drain oil from the continuously variable transmission 21 in the left traveling system is connected to the right traveling system through the casing h. After flowing into the casing of the step transmission 22, it is taken out via the external drain pipe i, and collected in a dedicated hydraulic oil tank T via the oil cooler OC. Further, the drain oil of the continuously variable transmission 23 of the working system is also collected in the hydraulic oil tank T via the external drain pipe j and the oil cooler OC.

  Next, the operation of the hydraulic servo system that operates the continuously variable transmissions 21 and 22 will be described. Since both hydraulic servo systems have the same specifications, the operation will be described using the hydraulic servo system of one continuously variable transmission 21.

  A pair of return springs 69 are incorporated in the servo cylinder 63, and as shown in FIG. 8 (a), when all the electromagnetic on-off valves 65 to 68 are in a non-energized state, the servo cylinder 63 has both return springs 69. To return to the neutral position. Then, as shown in FIG. 8B, one normally closed electromagnetic switching valve 65 is energized and opened, and one normally open electromagnetic switching valve 67 is energized and closed, so that the charge pump CP (1 ) Is supplied to the oil passage m (oil passage n in the servo cylinder 64), and the servo cylinder 63 operates from the neutral position to the forward side. Then, as shown in 8 (c), when the servo cylinder 63 is operated forward, the energization of the normally closed electromagnetic on-off valve 65 is stopped and returned to the closed position. Is prevented and the servo cylinder 63 is held in its forward position.

  Conversely, as shown in FIG. 8 (d), the other normally closed electromagnetic on-off valve 66 is energized and the other normally open electromagnetic on / off valve 68 is energized, so that the charge pump CP ( The pressure oil from 1) is supplied to the oil path q (oil path r in the servo cylinder 64), and the servo cylinder 63 operates from the neutral position to the reverse side. Then, as shown in FIG. 8 (e), when the normally closed electromagnetic on-off valve 66 is de-energized and returned to the closed position after the servo cylinder 63 is operated to the reverse side, the pressure oil from the oil path q is restored. The outflow is prevented and the servo cylinder 63 is held in the backward position.

  The valve units 61 and 62 are provided at operating positions of a single main transmission lever 71 provided in the control unit 6 that can swing back and forth and a steering lever 72 that functions as a single steering operation tool that can swing left and right. The feedback control is performed accordingly, and the control will be described below.

  As shown in the block diagram of FIG. 9, the operation position of the main transmission lever 71 and the operation position of the steering lever 72 are detected by potentiometers PM (1) and PM (2), respectively, and both the continuously variable transmission 21 22, the operation positions (swash plate angles) of the variable displacement pumps P (1) and P (2) are detected by the potentiometers PM (3) and PM (4) and fed back to the control device 70. The target shift positions of the continuously variable transmissions 21 and 22 are determined by the operation position of the main shift lever 71 and the operation position of the steering lever 72, and a shift by feedback control is performed toward the target shift position. The electromagnetic on-off valves 56 and 57 for linear clutch control are energized as described above based on the steering state detected by the potentiometer PM (2).

  When the main shift lever 71 is operated from neutral to forward or backward, the same target shift position corresponding to the amount of operation is set in both continuously variable transmissions 21 and 22, and variable displacement pumps P (1) and P (2) Are both moved forward or backward until they reach the target shift position, and are held at the target shift position. As a result, it is possible to perform forward / reverse shifting in a straight line. Further, when the steering lever 72 is operated from the neutral position to the left (or right) from the forward or reverse travel state, the continuously variable transmission 21 for left travel (or the continuously variable transmission 22 for right travel). ) Is corrected in the deceleration direction, and deceleration control is performed toward the corrected target shift position, and the aircraft has a strength corresponding to the lever operation amount in the direction in which the steering lever 72 is operated. It is linked so that it turns with a turning function.

  Here, the operation amount W of the steering lever 72 and the inside / outside speed ratio R of the left and right crawler traveling device 1 (ratio of the speed of the crawler traveling device 1 on the inside of the turn decelerated to the speed of the crawler traveling device 1 on the outside of the turn that is not decelerated). As shown in FIG. 14, when the steering lever 72 is operated to the maximum left or right, the speed of the crawler traveling device 1 on the inside of the turn is 0.3 times the speed of the crawler traveling device 1 on the outside of the turn. When the steering lever 72 is operated to the maximum in the “normal turning mode” in which the vehicle is decelerated, the speed of the crawler traveling device 1 on the inside of the turn is −0.3 times the speed of the crawler traveling device 1 on the outside of the turn (0.3 times in reverse). ) 2 types of “small turning mode” that can be decelerated until the vehicle is set in advance by map data or the like. There has to be selected and set by turning the mode selection switch SW. The turning mode selection switch SW is operated by a return type push button 75 as a turning mode changing operation tool provided in the grip portion 72a of the steering lever 72, as shown in FIG. When the push button 75 is not pushed, the “normal turning mode” is set, and when the push button 75 is pushed, the “small turning mode” is set.

  Therefore, for example, when the steering lever 72 is operated to the left without pressing the push button 75 in a state where the vehicle is moving straight forward at the speed set by the main transmission lever 71, the one continuously variable transmission 21 is " The forward speed of the crawler traveling device 1 on the left side is reduced based on the characteristics of the “normal turning mode”, and the aircraft turns to the left side due to the difference between the left and right speeds. When the steering lever 72 is operated to the left as much as possible, the left crawler traveling device 1 on the inside of the turn is decelerated to a forward speed 0.3 times that of the right crawler traveling device 1 on the outside of the turn.

  When the steering lever 72 is operated to the left while pressing the push button 75, the one continuously variable transmission 21 is decelerated based on the characteristics of the “small turning mode” in FIG. In this case, when the continuously variable transmission 21 is decelerated to the neutral position, the left crawler traveling device 1 on the inner side of the turn is stopped and the pivot is performed, and the speed is shifted to the reverse side beyond the neutral position. Thus, the super-certain turning is performed by reversing the crawler traveling device 1 on the left side which is inside the turning. However, in this super turning, the crawler traveling device 1 on the inner side of the turn is driven to rotate in reverse only at a speed not more than 0.3 times the speed of the crawler traveling device 1 on the outer side of the turn.

  In addition, when the push button 75 is pressed while the steering lever 72 is being operated to a certain steering position x in the “normal turning mode”, the turning mode is switched to the “turn turning mode” and becomes the inside of the turning. The crawler traveling device 1 is greatly decelerated, and when the pushing operation of the push button 75 is released, the crawler traveling device 1 returns to the original decelerating state, and the push button 75 is repeatedly pushed during the steering operation of the steering lever 72. Thus, it is possible to perform a small turn by small amounts, that is, a turn by so-called inching.

  As shown in FIGS. 6 and 9, the variable displacement pump P (3) of the continuously variable transmission 23 that controls the cutting unit 3 is shifted by an actuator 73 such as an electric motor. The continuously variable transmission 23 of the work system is interlocked with the forward shift operation of the main shift lever 70 so that the relationship between the forward travel speed Va and the cutting work unit drive speed Vb has characteristics set in advance by map data or the like. The target shift position is automatically determined, and the continuously variable transmission 23 is feedback-controlled toward the target shift position. The speed change position of the continuously variable transmission 23 is detected by the potentiometer PM (5) as the operation position (swash plate angle) of the variable displacement pump P (3).

  As shown in FIG. 10, the relationship between the forward travel speed Va and the mowing operation unit drive speed Vb is “a napped mode” in which the mowing operation unit drive speed Vb changes substantially linearly with respect to the change in the forward travel speed Va. The cutting operation unit driving speed Vb is set to two types of cutting modes, “falling mode” in which the cutting operation unit driving speed Vb rises significantly in the low speed range and decreases less in the high speed range. Any of the cutting modes can be selected by the cutting mode selection switch S (1) as the selection means.

  In addition, when the napping mode temporary changeover switch S (2) is turned on while the “napping mode” or the “inclination mode” is selected by the mowing mode selection switch S (1), the mowing is performed only during the turning operation. When the other cutting mode different from the cutting mode selected by the mode selection switch S (1) is set and the on / off operation of the temporary cutting mode switch S (2) is canceled, the cutting mode selection switch S (1) is selected. It returns to the original mowing mode.

  As shown in FIG. 12, the reaping mode temporary changeover switch S (2) is configured to be operated by a push button 74 as an operation tool provided on the front surface of the grip portion 71a of the main transmission lever 71. The mowing mode temporary changeover switch S (2) is turned on and operated by lightly pressing the push button 74 with the middle finger or the like of the left hand placed so as to cover the grip 71a of the main transmission lever 71.

  Therefore, in the field with many napped crops, the cutting mode selection switch S (1) is set to “Napping mode”, and in the field with many lying crops, the cutting mode selection switch S (1) is set to “Sloped mode”. Do work. And, for example, when entering the local lodging area during the work in the “napped mode”, the push button 74 of the main speed change lever 71 can be continuously operated, so that it can be temporarily switched to the “lodging mode” only during that time. When the user falls out of the lying area, the operator can return to the original work in the “napping mode” by releasing the finger from the push button 74. On the other hand, when entering the local raised region during work in the “liedown mode”, by continuing to push the push button 74, it is possible to temporarily switch to the “raised mode” only during that time. When released, the finger can be released from the push button 74 to return to the original work in the “inclination mode”.

[Another embodiment]
The present invention can be carried out by being modified into the following forms.
(1) As shown in FIGS. 15 and 16, the turning mode change operation tool 75 is constituted by a return type trigger provided in the grip portion 72 a of the steering lever 72, and the operation amount of the turning mode change operation tool 75 is changed. The potentiometer PM (6) is configured to be detectable, and when the turning mode change operation tool 75 is not operated, the “normal turning mode” in FIG. 14 is set, and as the operation amount of the turning mode change operation tool 75 increases. The turning mode characteristics can be set so as to approach the “small turning mode” in a continuous or stepwise manner. According to this, the turning characteristics can be changed by adjusting the turning mode change operation tool 75. Can be arbitrarily changed.
(2) The continuously variable transmission for the traveling system and the working system can be implemented by a belt type or other mechanical type.
(3) A steering handle that can be rotated left and right can be used as a steering operating tool.
(4) As a turning mode changing operation tool, a returnable small lever, dial, or the like that can be operated by a finger can be used.

Overall side view of the self-detaching combine as seen from the left Front view showing schematic configuration of transmission structure Longitudinal front view of the mission case Longitudinal front view around the straight clutch Side view of mission case shaft arrangement as seen from the left side of the aircraft Hydraulic circuit diagram Hydraulic circuit diagram for sub-transmission mechanism and linear clutch operation Hydraulic circuit diagram showing each operation of servo cylinder Block diagram showing control system of continuously variable transmission Characteristic diagram showing the relationship between the running speed and the cutting unit drive speed Front view of traveling device Perspective view of main transmission lever Perspective view of steering operation tool Characteristic diagram of swivel mode Side view of the steering operation tool of another embodiment Block diagram in another embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crawler travel device 21 Continuously variable transmission 22 Continuously variable transmission 72 Steering operation tool 75 Turning mode change operation tool

Claims (5)

A steering structure of a work machine configured to give a speed difference to the left and right crawler travel devices by operating a steering operation tool, and to turn the machine body according to a direction in which the steering operation tool is operated,
A turning mode change operation tool is provided, and by operating the turning mode change operation tool, the speed ratio of the left and right crawler travel devices set according to the operation amount of the steering operation tool is changed, and the fuselage is operated by the steering operation tool. A steering structure for a working machine, characterized in that it is configured to be in a turning mode that enhances a turning function when the steering operation is performed. The left and right crawler travel devices are configured to be driven by a hydraulic continuously variable transmission capable of continuously variable speed continuously in the forward and reverse ranges, and one of the crawler travel devices on the inner side of the turning is connected to the steering operation tool. The steering structure for a working machine according to claim 1, wherein the steering structure is configured to control in a deceleration direction by an operation. 3. The steering structure for a working machine according to claim 2, wherein in the turning mode in which the turning mode change operation tool is operated, the continuously variable transmission on the side to be decelerated is set so as to be capable of shifting to a reverse rotation range exceeding neutral. The turning mode change operation tool is configured as a return-type push button. When the push button is not pushed, a turning mode with a low turning function is set, and when the push button is pushed, a turning mode with a high turning function is set. The steering structure for a work machine according to any one of claims 1 to 3, wherein the steering structure is configured to be set. The operation amount of the turning mode changing operation tool is configured to be detectable, and the turning mode having a higher turning function is set as the detected operation amount is larger. Steering structure of the working machine described.

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