Crawler-type work machine

Abstract

A crawler-type work machine is provided. A bulldozer (1) engages left and right turning clutches (40L, 40R), releases left and right turning brakes (50L, 50R), and drives a turning motor (80) with a number of revolutions of an inner output shaft (60 IN ) lower than a number of revolutions of an outer output shaft (60 OUT ) as an amount of operation of a direction lever (35) increases, in a case where the amount of operation of the direction lever (35) is larger than a first prescribed amount (TH1) and smaller than a second prescribed amount (TH2). A controller (100) reduces a rate of engagement of the inner turning clutch (40 IN ), and brakes the inner turning brake (50 IN ), in a case where the amount of operation of the direction lever (35) is the second prescribed amount (TH2) or more.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a track-type working machine. BACKGROUND

[0002] Conventionally, a track-type working machine (for example, a bulldozer or the like) is known that has an input shaft that rotates using power of an engine, left and right steering clutches that transmit or cut off the rotational power from the input shaft to left and right output shafts, and left and right steering brakes that brake the left and right output shafts (for example, refer to Patent Literature 1).

[0003] The track-type working machine described in Patent Literature 1, when a direction operating lever is operated in either of left and right directions during traveling, releases the steering clutch corresponding to the operation direction, and half-brakes the steering brake corresponding to the operation direction, thereby making a gentle turn.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2010-144598 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] However, in the track-type working machine described in Patent Literature 1, since the gentle turn is performed using the braking force of the steering brake, the engine can suffer a power loss.

[0009] An object of the present disclosure is to provide a track-type working machine that can suppress a power loss of an engine in a gentle turn.

[0010] MEANS FOR SOLVING THE PROBLEMS

[0011] One aspect of the present disclosure is a track-type working machine having a left and right planetary gear mechanism, left and right steering clutches, left and right steering brakes, a turning motor, a direction operating lever, and a controller. The left and right planetary gear mechanisms are disposed between an input shaft and left and right output shafts. The left and right steering clutches are rotatable about the input shaft, and switch transmission and cutoff of rotational power from the input shaft to the left and right output shafts by the left and right planetary gear mechanisms. The left and right steering brakes brake the left and right output shafts. The turning motor causes the left and right output shafts to have a difference in number of revolutions, thereby rotating the left and right steering clutches. The direction operating lever is operable in a left turning direction and a right turning direction with a neutral position as a reference. The controller controls the left and right steering clutches, the left and right steering brakes, and the turning motor in accordance with an operation direction and an operation amount of the direction operating lever. When the operation amount is greater than a first prescribed amount and less than a second prescribed amount, the controller causes the left and right steering clutches to engage, causes the left and right steering brakes to release, and causes the turning motor to be driven such that, among the left and right output shafts, an inner side output shaft corresponding to the operation direction has a lower number of revolutions than an outer side output shaft opposite to the operation direction as the operation amount increases. When the operation amount is the second prescribed amount or more, the controller causes an engagement rate of an inner side steering clutch corresponding to the operation direction among the left and right steering clutches to decrease, and causes an inner side steering brake corresponding to the operation direction among the left and right steering brakes to brake.

[0012] Effects of the Invention

[0013] According to the technology of the present disclosure, it is possible to provide a track-type working machine that can suppress loss of engine power in gentle turning. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a perspective view of a bulldozer that is an embodiment.

[0015] Figure 2 is a structural sectional view of a power transmission system of the bulldozer that is an embodiment.

[0016] Figure 3 is a system structure overview diagram of the power transmission system of the bulldozer that is an embodiment.

[0017] Figure 4 is a flowchart for explaining a turning control method of an embodiment.

[0018] Figure 5 is a graph showing one example of a state of the bulldozer of an embodiment.

[0019] Figure 6 is a system structure overview diagram of a power transmission system of a bulldozer of a third modified example. DETAILED DESCRIPTION

[0020] (Structure of Bulldozer 1)

[0021] Figure 1 This is a perspective view of bulldozer 1, which is an example of tracked construction machinery. Figure 2 This is a structural cross-sectional view of the power transmission system of bulldozer 1. Figure 3 This is a system structure outline diagram of the power transmission system of bulldozer 1.

[0022] like Figure 1 As shown, the bulldozer 1 has: left and right travel devices 4L and 4R including left and right sprockets 2L and 2R and left and right tracks 3L and 3R, a bulldozer blade 5 installed at the front of the vehicle, and a soil loosening device 6 installed at the rear of the vehicle.

[0023] The bulldozer 1 can use the bulldozer blades 5 to perform bulldozing and other operations, and use the loosening device 6 to perform crushing and excavation operations.

[0024] like Figure 2 and Figure 3 As shown, the bulldozer 1 includes: an engine 10, an engine power transmission unit 20, left and right planetary gear mechanisms 30L and 30R, left and right steering clutches 40L and 40R, left and right steering brakes 50L and 50R, left and right output shafts 60L and 60R, a steering motor 80, a motor power transmission unit 90, and a controller 100.

[0025] [Engine Power Transmission Unit]

[0026] The engine power transmission unit 20 transmits power from the engine 10 to the left and right planetary gear mechanisms 30L and 30R. The engine power transmission unit 20 includes: a power take-off device 21, a torque converter 22, a transmission 23, a pinion 24, a bevel gear 25, and an input shaft 26.

[0027] The power take-off unit 21 transmits power from the engine 10 to the torque converter 22. The torque converter 22 transmits the power from the engine 10 via the power take-off unit 21 to the transmission 23 via fluid. The transmission 23 includes multiple speed clutches for changing the rotational power transmitted from the torque converter 22, and a direction clutch for switching between forward and reverse. The transmission 23 is connected to a pinion gear 24. Power from the transmission 23 is transmitted to the input shaft 26 via the pinion gear 24 and bevel gear 25. The input shaft 26 extends in the left-right direction. The axial direction of the input shaft 26 is the same as the left-right direction of the bulldozer 1.

[0028] Planetary gear mechanism

[0029] The left and right planetary gear mechanisms 30L, 30R are provided between the input shaft 26 and the left and right output shafts 60L, 60R. The left and right planetary gear mechanisms 30L, 30R have left and right ring gears 31L, 31R, left and right planetary gears 32L, 32R, left and right sun gears 33L, 33R, and left and right carriers 34L, 34R.

[0030] The left and right ring gears 31L, 31R are coupled to the input shaft 26. The left and right planetary gears 32L, 32R are provided inside the left and right ring gears 31L, 31R in a radial direction perpendicular to the axial direction of the input shaft 26. The left and right planetary gears 32L, 32R are engaged with the left and right ring gears 31L, 31R and the left and right sun gears 33L, 33R. The left and right sun gears 33L, 33R are rotatably attached with respect to the input shaft 26. The left and right sun gears 33L, 33R are provided inside the left and right planetary gears 32L, 32R in the radial direction. The left and right sun gears 33L, 33R are coupled to the left and right steering clutches 40L, 40R. The left and right sun gears 33L, 33R are separable and connectable to the motor power transmission portion 90 (specifically, the left and right clutch gears 91L, 91R described later) via the left and right steering clutches 40L, 40R. The left and right carriers 34L, 34R are coupled to the left and right planetary gears 32L, 32R and the left and right output shafts 60L, 60R.

[0031] [Steering Clutch]

[0032] The left and right steering clutches 40L, 40R are provided between the left and right planetary gear mechanisms 30L, 30R and the motor power transmission portion 90. The left and right steering clutches 40L, 40R separate and connect the left and right sun gears 33L, 33R of the left and right planetary gear mechanisms 30L, 30R and the left and right clutch gears 91L, 91R of the motor power transmission portion 90.

[0033] The left and right steering clutches 40L, 40R are driven by supplying hydraulic oil. The left and right steering clutches 40L, 40R are configured by wet multi-plate clutches that can be engaged and released. In the present embodiment, the left and right steering clutches 40L, 40R are positive type hydraulic clutches. The left and right steering clutches 40L, 40R are released when no hydraulic oil is supplied, partially engaged when the oil pressure of the supplied hydraulic oil is less than a predetermined value, and fully engaged when the oil pressure of the supplied hydraulic oil is equal to or greater than the predetermined value.

[0034] The oil pressure of the hydraulic oil supplied to the left and right steering clutches 40L, 40R is controlled by the left and right clutch control valves 27L, 27R. The engagement rate of the left and right steering clutches 40L, 40R changes from 0% to 100% (maximum) depending on the oil pressure of the supplied hydraulic oil.

[0035] The left and right steering clutches 40L, 40R switch the transmission and cutoff of the rotational power by the left and right planetary gear mechanisms 30L, 30R from the input shaft 26 to the left and right output shafts 60L, 60R.

[0036] Specifically, when the left steering clutch 40L is engaged, the rotation of the input shaft 26 is transmitted to the left output shaft 60L via the left ring gear 31L, the left planetary gear 32L, and the left carrier 34L. On the other hand, when the left steering clutch 40L is released, the left sun gear 33L becomes in a free rotation state, and the transmission of the rotational power from the input shaft 26 to the left output shaft 60L is cut off. Similarly, the right steering clutch 40R switches the transmission and cutoff of the rotational power from the input shaft 26 to the right output shaft 60R according to the engagement and release.

[0037] Here, the left and right steering clutches 40L, 40R can rotate around the input shaft 26 as a center. The left and right steering clutches 40L, 40R rotate in mutually opposite directions by the rotational power from the turning motor 80 transmitted via the motor power transmission portion 90.

[0038] For example, when the left steering clutch 40L is rotating forward and the right steering clutch 40R is rotating reverse in a state where the left and right steering clutches 40L, 40R are engaged, the number of revolutions of the left output shaft 60L is higher than that of the right output shaft 60R, and the bulldozer 1 turns right gently.

[0039] In the present specification, the gentle turn refers to advancing or retreating by making the left and right output shafts 60L, 60R rotating in the same direction generate a difference in the number of revolutions to draw an arc with a relatively large turning radius.

[0040] Further, when the left steering clutch 40L is rotating forward in a state where the left steering clutch 40L is engaged and the right steering clutch 40R is released, the left output shaft 60L rotates as the rotation of the right output shaft 60R stops, and the bulldozer 1 turns right sharply. However, in the case where the bulldozer 1 turns right sharply, the right steering brake 50R brakes the right output shaft 60R as described later.

[0041] In the present specification, the sharp turn is a concept including a pivot turn and a quasi-pivot turn. The pivot turn refers to turning by rotating one of the left and right output shafts 60L, 60R and completely stopping the other, in a state where the track on the other side is completely stopped to turn as an axis. The quasi-pivot turn refers to turning by rotating one of the left and right output shafts 60L, 60R and allowing a little rotation of the other, in a state where the track on the other side is virtually stopped.

[0042] As Figure 2As shown, the right turning clutch 40R has a plurality of clutch plates 41, a plurality of clutch disks 42, and a clutch piston 43.

[0043] Each clutch plate 41 is attached to the right clutch gear 91R. Each clutch disk 42 is fixed to the right sun gear 33R. Each clutch plate 41 and each clutch disk 42 are alternately arranged in the axial direction.

[0044] When the clutch piston 43 moves in the left direction with the supply of the working oil, each clutch plate 41 and each clutch disk 42 are pressed, and the right turning clutch 40R is engaged. Thus, the right sun gear 33R of the right planetary gear mechanism 30R is engaged with the right clutch gear 91R of the motor power transmission portion 90.

[0045] On the other hand, when the clutch piston 43 moves in the right direction with the discharge of the working oil, each clutch plate 41 and each clutch disk 42 are separated, and the right turning clutch 40R is released. Thus, the right sun gear 33R of the right planetary gear mechanism 30R is separated from the right clutch gear 91R of the motor power transmission portion 90.

[0046] Note that the left turning clutch 40L has the same structure as the right turning clutch 40R.

[0047] [Turning Brake]

[0048] The left and right turning brakes 50L, 50R are driven by the supply of the working oil. The left and right turning brakes 50L, 50R are configured by wet multi-plate clutches that can be engaged and released. In the present embodiment, the left and right turning brakes 50L, 50R are negative type hydraulic brakes. The left and right turning brakes 50L, 50R are fully engaged when no working oil is supplied, are partially engaged when the oil pressure of the supplied working oil is less than a prescribed value, and are released when the oil pressure of the supplied working oil is equal to or more than the prescribed value. When the left and right turning brakes 50L, 50R are engaged (fully engaged or partially engaged), the left and right turning brakes 50L, 50R generate a braking force.

[0049] The oil pressure of the working oil supplied to the left and right turning brakes 50L, 50R is controlled by the left and right brake control valves 28L, 28R. When the left and right turning brakes 50L, 50R are engaged (fully engaged or partially engaged), the left and right turning brakes 50L, 50R generate a braking force. The braking force of the left and right turning brakes 50L, 50R changes from 0% to 100% (maximum) depending on the oil pressure of the supplied working oil.

[0050] The left and right turning brakes 50L, 50R brake the rotation of the left and right output shafts 60L, 60R.

[0051] Specifically, when the left turning brake 50L is engaged, the rotation of the left output shaft 60L is braked, whereby the rotation of the left sprocket 2L is reduced. On the other hand, when the right turning brake 50R is engaged, the rotation of the right output shaft 60R is braked, whereby the rotation of the right sprocket 2R is reduced.

[0052] As shown in FIG. 1, the right turning brake 50R has a rotating member 51, a brake housing 52, a plurality of fixed pieces 53, a plurality of brake discs 54, and a brake piston 55. Figure 2

[0053] The rotating member 51 is fixed to the right output shaft 60R and rotates with the right output shaft 60R. The brake housing 52 is fixed with respect to the rotating member 51. Each fixed piece 53 is attached to the brake housing 52. Each brake disc 54 is fixed to the rotating member 51. Each fixed piece 53 and each brake disc 54 are alternately arranged in the axial direction.

[0054] When the brake piston 55 moves to the left direction with the filling of the working oil, each fixed piece 53 is separated from each brake disc 54, and the right turning brake 50R is released. On the other hand, when the brake piston 55 moves to the right direction with the discharge of the working oil, each fixed piece 53 is pressed against each brake disc 54, and the right turning brake 50R generates a braking force.

[0055] Note that the left turning brake 50L has the same structure as the right turning brake 50R.

[0056] [Turning motor]

[0057] The turning motor 80 is driven by the power of the engine 10. The turning motor 80 rotates in either of the forward rotation direction and the reverse rotation direction. The rotation direction and the number of revolutions of the turning motor 80 are controlled by the controller 100. The number of revolutions of the turning motor 80 varies from 0% to 100% (maximum) depending on the power transmitted from the engine 10.

[0058] The rotational power of the turning motor 80 is transmitted to the left and right turning clutches 40L, 40R via the motor power transmission portion 90. The turning motor 80 rotates the left and right turning clutches 40L, 40R by causing a difference in the number of revolutions between the left and right output shafts 60L, 60R. For example, when the bulldozer 1 is gently turning to the right, the turning motor 80 reversely rotates the left and right turning clutches 40L, 40R, and the number of revolutions of the left output shaft 60L is higher than that of the right output shaft 60R. In addition, when the bulldozer 1 is turning on the spot to the right, the turning motor 80 reversely rotates the left and right turning clutches 40L, 40R, but the right turning clutch 40R is released and the right turning brake 50R is braked, so the right output shaft 60R does not rotate and only the left output shaft 60L rotates. ​

[0059] [motor power transmission section]

[0060] The motor power transmission section 90 is disposed between the cornering motor 80 and the left and right steering clutches 40L, 40R. The motor power transmission section 90 transmits the rotational power of the cornering motor 80 to the left and right steering clutches 40L, 40R.

[0061] The motor power transmission section 90 has left and right clutch gears 91L, 91R, a first transmission gear 92, a lay shaft 93, a second transmission gear 94, an idler gear 95, and a pinion gear 96.

[0062] The left and right clutch gears 91L, 91R are separable / couplable to the left and right sun gears 33L, 33R via the left and right steering clutches 40L, 40R. The left and right clutch gears 91L, 91R are rotatable about the axial direction of the input shaft 26. The left clutch gear 91L is engaged with the idler gear 95. The right clutch gear 91R is linked to the idler gear 95 via the first transmission gear 92, the lay shaft 93, and the second transmission gear 94. The left and right clutch gears 91L, 91R rotate in opposite directions to each other when the cornering motor 80 rotates.

[0063] The idler gear 95 is engaged with the left clutch gear 91L, the second transmission gear 94, and the pinion gear 96. The idler gear 95 is rotatable about the axial direction of the input shaft 26.

[0064] The pinion gear 96 is engaged with the idler gear 95. The pinion gear 96 is rotatable about a pinion gear shaft 96a. The pinion gear 96 rotates by the rotational power of the cornering motor 80 transmitted via the pinion gear shaft 96a.

[0065] [controller]

[0066] The controller 100 is connected to the direction lever 35 for the steering operation of the bulldozer 1. The direction lever 35 is operable in the left turning direction P2 and the right turning direction P3 with the neutral position PI as a reference. The operator can make the bulldozer 1 turn gently and sharply (quasi- and true-pan turn) to the left and right by adjusting the operation direction and the operation amount of the direction lever 35.

[0067] The controller 100 controls the number of revolutions of the engine 10 and the speed range clutch and the direction range clutch of the transmission 23 in order to make the bulldozer 1 travel.

[0068] The controller 100 controls the left and right steering clutches 40L, 40R, the left and right steering brakes 50L, 50R, and the cornering motor 80 in accordance with the operation direction and the operation amount of the direction lever 35 in order to make the bulldozer 1 turn during the travel of the bulldozer 1.

[0069] The controller 100 switches the travel mode of the bulldozer 1 to any of the "straight travel mode", "gentle turning mode", "quasi-omnidirectional turning mode", and "omnidirectional turning mode" in accordance with the amount of operation of the direction lever 35.

[0070] The controller 100 makes the travel mode of the bulldozer 1 the straight travel mode in a case where the amount of operation of the direction lever 35 is equal to or smaller than a first prescribed amount TH1. The controller 100 makes the travel mode of the bulldozer 1 the gentle turning mode in a case where the amount of operation of the direction lever 35 is larger than the first prescribed amount TH1 and smaller than a second prescribed amount TH2. The controller 100 makes the travel mode of the bulldozer 1 the quasi-omnidirectional turning mode in a case where the amount of operation of the direction lever 35 is equal to or larger than the second prescribed amount TH2 and smaller than a third prescribed amount TH3. The controller 100 makes the travel mode of the bulldozer 1 the omnidirectional turning mode in a case where the amount of operation of the direction lever 35 is equal to or larger than the third prescribed amount TH3.

[0071] The second prescribed amount TH2 is larger than the first prescribed amount TH1. The third prescribed amount TH3 is larger than the second prescribed amount TH2. Each of the first to third prescribed amounts TH1 to TH3 can be set to a desired value. The first prescribed amount TH1 can also be "0".

[0072] In the present specification, the "quasi-omnidirectional turning mode" and the "omnidirectional turning mode" are sometimes collectively referred to as the "sharp turning mode".

[0073] • Straight travel mode

[0074] In the straight travel mode, the controller 100 controls the left and right clutch control valves 27L, 27R so as to cause the left and right steering clutches 40L, 40R to engage. The engagement rates of the left and right steering clutches 40L, 40R are set to 100%.

[0075] In the straight travel mode, the controller 100 controls the left and right brake control valves 28L, 28R so as to cause the left and right steering brakes 50L, 50R to release. The brake forces of the left and right steering brakes 50L, 50R are set to 0%.

[0076] In the straight travel mode, the controller 100 stops the turning motor 80. The number of revolutions of the turning motor 80 is set to 0%.

[0077] • Gentle turning mode

[0078] In the gentle turning mode, the controller 100 controls the left and right clutch control valves 27L, 27R so as to cause the left and right steering clutches 40L, 40R to engage. The engagement rates of the left and right steering clutches 40L, 40R are each required to be a sufficiently high value, and are not particularly limited, but are preferably 90% or more, more preferably 95% or more, and particularly preferably 100%.

[0079] In the gentle turning mode, the controller 100 controls the left and right brake control valves 28L, 28R to cause the left and right turning brakes 50L, 50R to be released. The braking force of the left and right turning brakes 50L, 50R is set to 0%.

[0080] In the gentle turning mode, the controller 100 causes the inner output shaft 60 IN to be driven at a lower number of revolutions than the outer output shaft 60 OUT as the amount of operation of the direction operating lever 35 increases.

[0081] The inner output shaft 60 IN is the output shaft among the left and right output shafts 60L, 60R that corresponds to the direction of operation of the direction operating lever 35, that is, the turning direction. The outer output shaft 60 OUT is the output shaft among the left and right output shafts 60L, 60R that is opposite to the direction of operation of the direction operating lever 35.

[0082] The controller 100 increases the number of revolutions of the turning motor 80 as the amount of operation of the direction operating lever 35 increases. For example, the controller 100 can gradually increase the number of revolutions of the turning motor 80 in proportion to the amount of operation of the direction operating lever 35, or can increase the number of revolutions of the turning motor 80 in stages according to the amount of operation of the direction operating lever 35.

[0083] The number of revolutions of the turning motor 80 when the amount of operation of the direction operating lever 35 is the second prescribed amount TH2 is not particularly limited as long as it is sufficiently high, but is preferably 90% or more, more preferably 95% or more, and particularly preferably 100% (the maximum value).

[0084] • The quasi-stationary turning mode

[0085] In the quasi-stationary turning mode, the controller 100 controls the left and right clutch control valves 27L, 27R to cause the engagement rate of the inner turning clutch 40 IN to be lower than in the gentle turning mode, and to maintain the engagement rate of the outer turning clutch 40 OUT at the same level as in the gentle turning mode.

[0086] The inner turning clutch 40 IN is the turning clutch among the left and right turning clutches 40L, 40R that corresponds to the direction of operation of the direction operating lever 35. The outer turning clutch 40 OUT is the turning clutch among the left and right turning clutches 40L, 40R that is opposite to the direction of operation of the direction operating lever 35.

[0087] The inner turning clutch 40 INThe target engagement rate only needs to be sufficiently low and is not particularly limited, but is preferably below 50%, more preferably below 10%, and particularly preferably 0%. The controller 100 can inversely proportionally to the amount of operation of the direction control lever 35 to engage the inner steering clutch 40. IN The engagement rate gradually decreases to the target value, or the inner steering clutch 40 can be engaged according to the amount of operation of the steering lever 35. IN The engagement rate decreases in stages. Alternatively, the controller 100 can also engage the inner steering clutch 40 when the steering lever 35 is operated at a second predetermined amount TH2. IN The binding rate was reduced to the target value.

[0088] Outer steering clutch 40 OUT The engagement rate only needs to be high enough and is not particularly limited, but it is preferably 90% or more, more preferably 95% or more, and particularly preferably 100%.

[0089] In the near-stationary turning mode, the controller 100 controls the control valves 28L and 28R of the left and right brakes, causing the inner steering brake 50 to engage. IN Braking, applying the outer steering brake 50 degrees. OUT release.

[0090] Inner steering brake 50 IN It refers to the steering brake among the left and right steering brakes 50L and 50R that corresponds to the operating direction of the steering lever 35. The outer steering brake 50... OUT It is the steering brake among the left and right steering brakes 50L and 50R that has the opposite operating direction to the steering lever 35.

[0091] Preferably, the controller 100 increases the inner steering brake 50 as the amount of operation of the steering lever 35 increases. IN The braking force. The controller 100 can increase the inner steering brake 50 proportionally to the amount of operation of the steering lever 35. IN The braking force can also be increased in stages by adjusting the amount of operation of the steering lever 35 on the inner steering brake 50. IN Braking force.

[0092] When the steering lever 35 is operated to the third specified amount TH3, the inner steering brake 50 IN The braking force only needs to be sufficiently high and is not particularly limited, but is preferably 90% or higher, more preferably 95% or higher, and particularly preferably 100%. Outer steering brake 50 OUT The braking force is the same as in the smooth turning mode, which is 0%.

[0093] In the quasi-spot turn mode, the controller 100 maintains the number of revolutions of the turn motor 80 to the same degree as that of the gentle turn mode. The number of revolutions of the turn motor 80 is not particularly limited as long as it is sufficiently high, but is preferably 90% or more, more preferably 95% or more, and particularly preferably 100%.

[0094] • Spot turn mode

[0095] In the spot turn mode, the controller 100 controls the left and right clutch control valves 27L, 27R to maintain the engagement rates of the inner and outer steering clutches 40 IN and 40 OUT , respectively, to the same degrees as those of the quasi-spot turn mode. The engagement rate of the inner steering clutch 40 IN is lower than that of the gentle turn mode.

[0096] The target value of the engagement rate of the inner steering clutch 40 IN is not particularly limited as long as it is sufficiently low, but is preferably 50% or less, more preferably 10% or less, and particularly preferably 0%. The engagement rate of the outer steering clutch 40 OUT is not particularly limited as long as it is sufficiently high, but is preferably 90% or more, more preferably 95% or more, and particularly preferably 100%.

[0097] In the spot turn mode, the controller 100 controls the left and right brake control valves 28L, 28R to fully engage the inner steering brake 50 IN and release the outer steering brake 50 OUT . The braking force of the inner steering brake 50 IN is 100%, and the braking force of the outer steering brake 50 OUT is 0%.

[0098] In the spot turn mode, the controller 100 maintains the number of revolutions of the turn motor 80 to the same degree as that of the quasi-spot turn mode. The number of revolutions of the turn motor 80 is not particularly limited as long as it is sufficiently high, but is preferably 90% or more, more preferably 95% or more, and particularly preferably 100%.

[0099] (Turn control method)

[0100] Next, the case where the amount of operation of the direction operating lever 35 gradually increases from 0 will be described with respect to the turn control method executed by the controller 100.

[0101] Figure 4 is a flowchart for explaining the turn control method. Figure 5 is a graph showing one example of the state of the bulldozer 1.

[0102] In step S1, when the amount of operation of the direction control lever 35 is less than or equal to a first predetermined amount TH1, the controller 100 causes the bulldozer 1 to travel in straight-line mode.

[0103] Specifically, the controller 100 engages the left and right steering clutches 40L and 40R, releases the left and right steering brakes 50L and 50R, and stops the steering motor 80. As a result, the bulldozer 1 moves straight.

[0104] In step S2, when the amount of operation of the direction control lever 35 is greater than the first predetermined amount TH1 and less than the second predetermined amount TH2, the controller 100 causes the bulldozer 1 to turn in the direction of operation of the direction control lever 35 in a smooth turning mode.

[0105] Specifically, controller 100 engages the left and right steering clutches 40L and 40R, releases the left and right steering brakes 50L and 50R, and engages the inner output shaft 60. IN The rotational speed increases with the increase in the amount of operation of the direction control lever 35 compared to the outer output shaft 60. OUT The low rotation speed drives the turning motor 80. This allows the bulldozer 1 to turn smoothly in the direction of the steering lever 35.

[0106] It should be noted that, in Figure 5 In the example shown, the rotation speed of the steering motor 80 is proportional to the amount of operation of the steering lever 35, gradually increasing from 0% to 100%.

[0107] In step S3, when the amount of operation of the direction control lever 35 is greater than or equal to the second predetermined amount TH2 and less than the third predetermined amount TH3, the controller 100 causes the bulldozer 1 to turn in the direction of operation of the direction control lever 35 in a quasi-stationary turning mode.

[0108] Specifically, controller 100 activates the inner steering clutch 40. IN The engagement rate decreases, causing the inner steering brake 50 IN Brake, and make the inner output shaft 60 IN The rotational speed ratio of the outer output shaft is 60. OUT The low rotation speed drives the turning motor 80. Thus, the bulldozer 1 turns precisely in the direction of the direction control lever 35.

[0109] It should be noted that, in Figure 5 In the example shown, the inner steering clutch 40 IN The engagement rate decreases from 100% to 0% in two stages based on the amount of operation of the steering lever 35, and the inner steering brake 50. IN The braking force increases from 0% to 100% in two stages, depending on the amount of operation of the direction control lever 35.

[0110] In step S4, the controller 100 turns the bulldozer 1 in the direction of operation of the direction lever 35 in the pivot turn mode in a case where the operation amount of the direction lever 35 is the third prescribed amount TH3 or more.

[0111] Specifically, the controller 100 maintains the engagement rates of the inner side turning clutch 40 IN and the outer side turning clutch 40 OUT at the same levels as those in the quasi-pivot turn mode, fully engages the inner side turning brake 50 IN , and releases the outer side turning brake 50 OUT . Further, the controller 100 maintains the number of revolutions of the turning motor 80 at the same level as that in the quasi-pivot turn mode. Thus, the bulldozer 1 turns in place in the direction of operation of the direction lever 35.

[0112] (Features) [1]

[0114] The controller 100 engages the left and right turning clutches 40L, 40R, releases the left and right turning brakes 50L, 50R, and drives the turning motor 80 with the number of revolutions of the inner side output shaft 60 IN being lower than that of the outer side output shaft 60 OUT as the operation amount of the direction lever 35 increases in a case where the operation amount of the direction lever 35 is larger than the first prescribed amount TH1 and smaller than the second prescribed amount TH2. Thus, the bulldozer 1 turns gently in the direction of operation of the direction lever 35.

[0115] The controller 100 reduces the engagement rate of the inner side turning clutch 40 IN and brakes the inner side turning brake 50 IN in a case where the operation amount of the direction lever 35 is the second prescribed amount TH2 or more. Thus, the bulldozer 1 turns sharply (in place or quasi-in place) in the direction of operation of the direction lever 35.

[0116] Thus, both gentle turning and sharp turning can be performed by controlling the left and right turning clutches 40L, 40R, the left and right turning brakes 50L, 50R, and the turning motor 80.

[0117] During gentle turning, since the left and right turning brakes 50L, 50R are released, power loss of the engine 10 can be suppressed as compared with a case where gentle turning is performed using the braking force of the left and right turning brakes 50L, 50R. Further, since the left and right turning brakes 50L, 50R are not used during gentle turning, the service life of the left and right turning brakes 50L, 50R can be extended. [2]

[0119] The controller 100 preferably sets the rotation speed of the steering motor 80 to 100% (maximum value) when the operation amount of the steering lever 35 is greater than or equal to the second predetermined amount TH2. This further suppresses the decrease in the center speed of the bulldozer 1 during sharp turns. [3]

[0121] Preferably, when the amount of operation of the steering lever 35 is greater than or equal to a second predetermined amount TH2 and less than a third predetermined amount TH3, the controller 100 increases the inner steering brake 50 as the amount of operation of the steering lever 35 increases. IN The braking force. Therefore, because there is a quasi-stationary turn between a gentle turn and a stationary turn, the controllability of the bulldozer 1 can be improved when switching from a gentle turn to a stationary turn. [4]

[0123] The controller 100 preferably activates the inner steering brake 50 when the steering lever 35 is operated to a third predetermined amount TH3. IN The braking force is 100% (maximum). This allows for a wider adjustment range of the turning radius for near-stationary turns. [5]

[0125] The controller 100 preferably engages the inner steering clutch 40 when the operation amount of the steering lever 35 is greater than or equal to the second predetermined amount TH2. IN The engagement rate is 0%. Therefore, the turning radius can be further reduced during sharp turns (especially near-stationary turns). [6]

[0127] Because the controller 100 drives the turning motor 80 during a sharp turn, it can reduce the turning radius of the bulldozer 1 during a sharp turn.

[0128] (Modifications of the implementation method)

[0129] This invention is not limited to the embodiments described above. Various modifications or variations can be made without departing from the scope of this invention.

[0130] (First variation)

[0131] In the above embodiment, in the quasi-stationary turning mode, the controller 100 increases the inner steering brake 50 as the amount of operation of the steering lever 35 increases. IN The braking force is limited, but the inner steering brake can also be applied at 50 degrees. IN The braking force is maintained at a specified value greater than 0%.

[0132] (Second variation)

[0133] In the above embodiment, the controller 100 allows the quasi-stationary turning mode to exist between the smooth turning mode and the stationary turning mode. However, the quasi-stationary turning mode may not exist, and the smooth turning mode and the stationary turning mode may be directly continuous. In this case, a sharp turn only indicates a stationary turn.

[0134] (Third variation)

[0135] In the above embodiments, the controller 100 switches from a gentle turning mode to a sharp turning mode (quasi-stationary turning mode and stationary turning mode) based on the amount of operation of the direction control lever 35, but is not limited thereto. The controller 100 may also switch from a gentle turning mode to a sharp turning mode if the amount of operation of the direction control lever 35 is greater than the first predetermined amount TH1 and a sharp turning instruction is received from the operator.

[0136] Here, Figure 6 This is a schematic diagram of the power transmission system of the bulldozer 1a in this modified example. Except for the sharp turn button 36, the bulldozer 1a has the same structure as the bulldozer 1 in the above embodiment.

[0137] The sharp turn button 36 is connected to the controller 100. The sharp turn button 36 receives sharp turn instructions from the operator. When the operator presses the sharp turn button 36, it sends a sharp turn instruction to the controller 100. The sharp turn button 36 can also send sharp turn instructions to the controller 100 while it is being pressed by the operator, or it can continuously send sharp turn instructions to the controller 100 until the operator presses it again.

[0138] When the amount of operation of the direction control lever 35 is less than or equal to a first predetermined amount TH1, the controller 100 sets the bulldozer 1 to a straight-line mode as described in the above embodiment.

[0139] When the amount of operation of the direction control lever 35 is greater than the first predetermined amount TH1 and no sharp turn instruction is received, the controller 100 sets the bulldozer 1 to a smooth turn mode. In the smooth turn mode, the controller 100 operates as described in the above embodiment.

[0140] However, in the above embodiment, a sharp turn mode is triggered when the operation amount of the direction control lever 35 is greater than or equal to the second predetermined amount TH2. But in this modified example, even if the operation amount of the direction control lever 35 is greater than or equal to the second predetermined amount TH2, a sharp turn mode is not triggered. Therefore, in this modified example, the direction control lever 35 is only used to make the bulldozer 1 turn smoothly.

[0141] The controller 100 makes the travel mode of the bulldozer 1 the sharp turn mode when the operation amount of the direction lever 35 is larger than the first prescribed amount TH1 and the sharp turn instruction is received. The control of the controller 100 in the sharp turn mode is as described in the above embodiment.

[0142] Note that, in the above embodiment, the operation amount of the direction lever 35 is used to switch from the quasi-pan turn mode to the pan turn mode, but in this modification, the controller 100 makes it the quasi-pan turn mode for a prescribed time after the sharp turn instruction is received, and makes it the pan turn mode after the prescribed time elapses. However, in this modification, the controller 100 can not have the quasi-pan turn mode, but can make the gentle turn mode and the pan turn mode directly continuous.

[0143] (Fourth Modification)

[0144] In the above embodiment, the left and right steering clutches 40L, 40R are active hydraulic clutches, but can be passive hydraulic clutches.

[0145] (Fifth Modification)

[0146] In the above embodiment, the left and right steering brakes 50L, 50R are passive hydraulic brakes, but can be active hydraulic brakes.

[0147] (Sixth Modification)

[0148] In the above embodiment, the left and right output shafts 60L, 60R are connected to the left and right sprockets 2L, 2R, but left and right final reduction devices can be provided between the left and right output shafts 60L, 60R and the left and right sprockets 2L, 2R.

[0149] (Seventh Modification)

[0150] In the above embodiment, the controller 100 drives the turning motor 80 in the sharp turn mode (the quasi-pan turn mode and the pan turn mode), but is not limited to this. The controller 100 can not drive the turning motor 80 in the quasi-pan turn mode, and can not drive the turning motor 80 in the pan turn mode.

[0151] Explanation of Reference Numerals

[0152] 1 bulldozer; 10 engine; 20 engine power transmission part; 26 input shaft; 30L, 30R left and right planetary gear mechanisms; 31L, 31R left and right ring gears; 32L, 32R left and right planetary gears; 33L, 33R left and right sun gears; 34L, 34R left and right carriers; 40L, 40R left and right steering clutches; 50L, 50R left and right steering brakes; 60L, 60R left and right output shafts; 80 turning motor; 90 motor power transmission part; 91L, 91R left and right clutch gears; 92 first transmission gear; 93 countershaft; 94 second transmission gear; 95 idler gear; 96 pinion gear; 98 fixed member; 99 turning motor; 100 controller.

Claims

1. A tracked operating machine, characterized in that, have: The left and right planetary gear mechanism is configured between the input shaft and the left and right output shafts; The left and right steering clutches are rotatable about the input shaft, and switch the transmission and disconnection of rotational power from the input shaft to the left and right output shafts by the left and right planetary gear mechanisms. Left and right steering brakes, which brake the left and right output shafts; A steering motor that causes a speed difference between the left and right output shafts, thereby rotating the left and right steering clutches; The steering lever can be operated in the left and right turning directions with the neutral position as a reference. The controller controls the left and right steering clutches, the left and right steering brakes, and the steering motor according to the operating direction and amount of the steering lever; When the operation amount is greater than the first predetermined amount and less than the second predetermined amount, the controller engages the left and right steering clutches, releases the left and right steering brakes, and drives the steering motor such that the rotation speed of the inner output shaft corresponding to the operation direction is lower than the rotation speed of the outer output shaft opposite to the operation direction as the operation amount increases. When the operation amount is greater than or equal to the second predetermined amount, the controller reduces the engagement rate of the inner steering clutch corresponding to the operation direction among the left and right steering clutches, brakes the inner steering brake corresponding to the operation direction among the left and right steering brakes, and keeps the steering motor constantly driven.

2. The tracked work machinery as described in claim 1, characterized in that, When the operation amount is greater than or equal to the second specified amount, the controller sets the rotation speed of the turning motor to the maximum value.

3. The tracked work machinery as described in claim 1, characterized in that, When the operation amount is greater than the second specified amount and less than the third specified amount, the controller increases the braking force of the inner steering brake as the operation amount increases.

4. The tracked work machinery as described in claim 3, characterized in that, When the operation amount is the third predetermined amount, the controller sets the braking force of the inner steering brake to the maximum value.

5. The tracked work machinery as described in claim 1, characterized in that, When the operation amount is greater than or equal to the second predetermined amount, the controller sets the engagement rate of the inner steering clutch to 0%.

6. A tracked operating machine, characterized in that, have: The left and right planetary gear mechanism is configured between the input shaft and the left and right output shafts; The left and right steering clutches are rotatable about the input shaft, and switch the transmission and disconnection of rotational power from the input shaft to the left and right output shafts by the left and right planetary gear mechanisms. Left and right steering brakes, which brake the left and right output shafts; A steering motor that causes a speed difference between the left and right output shafts, thereby rotating the left and right steering clutches; The steering lever can be operated in the left and right turning directions with the neutral position as a reference. The controller controls the left and right steering clutches, the left and right steering brakes, and the steering motor according to the operating direction and amount of the steering lever; When the operation amount is greater than the first predetermined amount and no sharp turn instruction is received from the operator, the controller engages the left and right steering clutches, releases the left and right steering brakes, and drives the steering motor such that the rotation speed of the inner output shaft corresponding to the operation direction is lower than the rotation speed of the outer output shaft opposite to the operation direction as the operation amount increases. When the operation amount is greater than the first specified amount and the sharp turn instruction is received, the controller reduces the engagement rate of the inner steering clutch corresponding to the operation direction among the left and right steering clutches, brakes the inner steering brake corresponding to the operation direction among the left and right steering brakes, and keeps the turning motor constantly driven.

7. The tracked work machinery as described in claim 6, characterized in that, When the operation amount is greater than the first specified amount and the sharp turn instruction is received, the controller sets the rotation speed of the turning motor to the maximum value.

8. The tracked work machinery as described in claim 6, characterized in that, When the operation amount is greater than the first predetermined amount and the sharp turn instruction is received, the controller sets the braking force of the inner steering brake to the maximum value.

9. The tracked work machinery as described in claim 6, characterized in that, When the operation amount is greater than the first predetermined amount and the sharp turn instruction is received, the controller sets the engagement rate of the inner steering clutch to 0%.

10. The tracked work machinery as described in claim 6, characterized in that, It has a sharp turn button that receives the sharp turn instruction from the operator.

11. The tracked work machine as described in any one of claims 1 to 10, characterized in that, Each of the left and right planetary gear mechanisms has: A gear ring, which is connected to the input shaft; The sun gear, which is rotatably mounted on the input shaft, is connected to the steering clutch; A planetary gear, disposed between the ring gear and the sun gear; Planetary carrier, which is connected to the planetary gears and the output shaft.

12. The tracked work machinery as described in claim 11, characterized in that, have: The left and right clutch gears can be disengaged / engaged from the sun gears of the left and right planetary gear mechanisms via the left and right steering clutches, and rotate in opposite directions. The idler gear transmits the rotational power of the turning motor to the left and right clutch gears.

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