Tracked work machine

Abstract

To provide a crawler-type work machine capable of suppressing deterioration in operability of the work machine.SOLUTION: In a bulldozer 1, when an angle cylinder 8 and an elevation cylinder 9 are driven while a swing motor 80 is being rotated, a controller 110 executes hydraulic oil amount control to reduce the amount of hydraulic oil supplied from a hydraulic pressure supply unit 100 to the swing motor 80.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a track-type work machine. [Background technology]

[0002] BACKGROUND ART Conventionally, a crawler-type work machine (for example, a bulldozer) that can turn left and right using a turning motor is known (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2020 / 0247468 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 does not consider the case where a track-type work machine is equipped with a work implement, but when the track-type work machine is equipped with a work implement, if the hydraulic supply unit for the swing motor is also used for the work implement, the amount of hydraulic oil that can be distributed to the work implement may be insufficient, resulting in a decrease in the operability of the work implement.

[0005] An object of the present disclosure is to provide a track-type work machine that is capable of suppressing a decrease in the operability of the work implement. [Means for solving the problem]

[0006] A track-type work machine according to one aspect of the present disclosure includes left and right steering brakes, a swing motor, a work implement cylinder, a hydraulic supply unit, and a controller. The left and right steering brakes brake the left and right output shafts. The swing motor generates a difference in rotation speed between the left and right output shafts. The work implement cylinder drives a work implement attached to the vehicle body. The hydraulic supply unit supplies hydraulic oil to each of the swing motor and the work implement cylinder. The controller controls the hydraulic supply unit. When the work implement cylinder is driven while the swing motor is rotating, the controller performs hydraulic oil amount control to reduce the amount of hydraulic oil supplied to the swing motor from the hydraulic supply unit. [Effects of the Invention]

[0007] According to the technology disclosed herein, it is possible to provide a track-type work machine that is capable of suppressing a decrease in the operability of the work implement. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a bulldozer according to a first embodiment. [Figure 2] FIG. 1 is a cross-sectional configuration diagram of a power transmission system of a bulldozer according to a first embodiment. [Figure 3] 1 is a schematic system configuration diagram of a power transmission system of a bulldozer according to a first embodiment. [Figure 4] FIG. 10 is a schematic system configuration diagram of a power transmission system of a bulldozer according to a second embodiment. [Figure 5] FIG. 11 is a schematic system configuration diagram of a power transmission system of a bulldozer according to a third modified example. [Figure 6] FIG. 13 is a schematic system configuration diagram of a power transmission system of a bulldozer according to a sixth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] 1. First embodiment

[0010] (External configuration of Bulldozer 1) FIG. 1 is a perspective view of a bulldozer 1, which is an example of a track-type working machine.

[0011] As shown in FIG. 1, a bulldozer 1 includes a vehicle body 2, a work implement 3, and a pair of left and right crawler units 1A.

[0012] The vehicle body 2 has a cab 4, an engine compartment 5, and a vehicle body frame (not shown). The cab 4 is disposed at the upper rear part of the vehicle body 2. The engine compartment 5 is disposed in front of the cab 4.

[0013] The work implement 3 is attached to the vehicle body 2. The work implement 3 has a blade 6, a frame 7, an angle cylinder 8, and a lifting cylinder 9. The blade 6 is an example of a "work implement" according to the present disclosure. The blade 6 is disposed in front of the vehicle body 2. The blade 6 is supported by the frame 7. The front end of the frame 7 is rotatably attached to the rear surface of the blade 6. The rear end of the frame 7 is rotatably supported on the side of the vehicle body 2.

[0014] The blade 6 is driven by an angle cylinder 8 and a lifting cylinder 9. The angle cylinder 8 and the lifting cylinder 9 are each an example of a "work machine cylinder" according to the present disclosure.

[0015] The front end of the angle cylinder 8 is rotatably supported on the rear surface of the blade 6. The rear end of the angle cylinder 8 is rotatably supported on the side of the vehicle body 2. The angle cylinder 8 expands and contracts hydraulically, causing the blade 6 to tilt in the front-rear direction.

[0016] The lower end of the lift cylinder 9 is rotatably supported on the upper surface of the frame 7. The middle part of the lift cylinder 9 is rotatably supported on the side of the vehicle body 2. The lift cylinder 9 extends and retracts hydraulically, causing the blade 6 to move up and down.

[0017] The pair of left and right track devices 1A are travel devices of the bulldozer 1. The pair of left and right track devices 1A are arranged so as to sandwich the vehicle body 2 therebetween.

[0018] Each of the pair of left and right crawler belt devices 1A has crawler belts 2A, driving wheels (sprockets) 3A, idler wheels 4A, and track frames 5A.

[0019] The crawler belt 2A is formed in an annular (endless) shape and is wound around the drive wheel 3A and the idler wheel 4A. The crawler belt 2A is engaged with the drive wheel 3A and rotates when the drive wheel 3A is rotated.

[0020] The drive wheels 3A and the track frame 5A are attached to the sides of the vehicle body 2. The drive wheels 3A are arranged behind the track frame 5A so that they can be rotated. The pair of left and right drive wheels 3A are supported by left and right output shafts 60L, 60R, which will be described later. The idler wheel 4A is rotatably arranged at the front end of the track frame 5A.

[0021] (Bulldozer 1 internal structure) 2 is a cross-sectional configuration diagram of the power transmission system of the bulldozer 1. FIG. 3 is a schematic system configuration diagram of the power transmission system of the bulldozer 1.

[0022] As shown in Figures 2 and 3, the bulldozer 1 has an engine 10, an engine power transmission unit 20, left and right planetary gear mechanisms 30L, 30R, left and right steering clutches 40L, 40R, left and right steering brakes 50L, 50R, left and right output shafts 60L, 60R, a swing motor 80, a motor power transmission unit 90, a hydraulic pressure supply unit 100, and a controller 110.

[0023] [Engine power transmission section] The engine power transmission unit 20 transmits power from the engine 10 to the left and right planetary gear mechanisms 30L, 30R. The engine power transmission unit 20 includes a power take-off device (power take-off) 21, a torque converter 22, a transmission 23, a pinion 24, a bevel gear 25, and an input shaft 26.

[0024] The power take-off device 21 distributes the power of the engine 10 to the torque converter 22 and a variable displacement pump 101 (described later). The torque converter 22 transmits the power of the engine 10 transmitted from the power take-off device 21 to the transmission 23 via a fluid. The transmission 23 has a plurality of speed-stage clutches for changing the speed of the rotational power transmitted from the torque converter 22, and a direction-stage clutch for switching between forward and reverse. The transmission 23 is connected to a pinion 24. The power from the transmission 23 is transmitted to an input shaft 26 via the pinion 24 and a bevel gear 25. The input shaft 26 extends in the left-right direction. The axial direction of the input shaft 26 is synonymous with the left-right direction of the bulldozer 1.

[0025] [Planetary gear mechanism] The left and right planetary gear mechanisms 30L, 30R are disposed between the input shaft 26 and the left and right output shafts 60L, 60R. The left and right planetary gear mechanisms 30L, 30R include 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.

[0026] The left and right ring gears 31L, 31R are connected to the input shaft 26. The left and right planetary gears 32L, 32R are arranged 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 mesh 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 to the input shaft 26. The left and right sun gears 33L, 33R are arranged inside the left and right planetary gears 32L, 32R in the radial direction. The left and right sun gears 33L, 33R are connected to the left and right steering clutches 40L, 40R. The left and right sun gears 33L, 33R can be connected to and disconnected from the motor power transmission unit 90 (specifically, left and right clutch gears 91L, 91R, which will be described later) via the left and right steering clutches 40L, 40R. The left and right carriers 34L, 34R are connected to the left and right planetary gears 32L, 32R and the left and right output shafts 60L, 60R.

[0027] [Steering clutch] The left and right steering clutches 40L, 40R are disposed between the left and right planetary gear mechanisms 30L, 30R and the motor power transmission unit 90. The left and right steering clutches 40L, 40R connect and disconnect 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 unit 90.

[0028] The left and right steering clutches 40L, 40R are driven by the supply of hydraulic oil. The left and right steering clutches 40L, 40R are configured as wet multi-plate clutches that can be engaged and disengaged. In this embodiment, the left and right steering clutches 40L, 40R are positive-type hydraulic clutches. The left and right steering clutches 40L, 40R are disengaged when no hydraulic oil is supplied, partially engaged when the hydraulic oil pressure supplied is below a predetermined value, and fully engaged when the hydraulic oil pressure supplied is equal to or greater than the predetermined value.

[0029] The hydraulic pressure of the hydraulic oil supplied to the left and right steering clutches 40L, 40R is controlled by left and right clutch control valves 27L, 27R. The left and right clutch control valves 27L, 27R are driven in response to a clutch hydraulic pressure command input from a controller 110.

[0030] The left and right steering clutches 40L, 40R switch between transmitting and cutting off rotational power from the input shaft 26 to the left and right output shafts 60L, 60R by the left and right planetary gear mechanisms 30L, 30R.

[0031] 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 disengaged, the left sun gear 33L enters a free rotation state, and the transmission of rotational power from the input shaft 26 to the left output shaft 60L is cut off. Similarly, the right steering clutch 40R switches between transmitting and cutting off rotational power from the input shaft 26 to the right output shaft 60R depending on whether it is engaged or disengaged.

[0032] Here, the left and right steering clutches 40L, 40R are rotatable around the input shaft 26. The left and right steering clutches 40L, 40R rotate in opposite directions to each other by the rotational power from the swing motor 80 transmitted via the motor power transmission unit 90.

[0033] For example, when the left and right steering clutches 40L, 40R are engaged and the left steering clutch 40L rotates forward while the right steering clutch 40R rotates reversely, the rotation speed of the left output shaft 60L becomes higher than the rotation speed of the right output shaft 60R, causing the bulldozer 1 to make a gentle turn to the right.

[0034] In this specification, gentle turning means moving forward or backward in an arc with a relatively large turning radius by generating a difference in rotation speed between the left and right output shafts 60L, 60R that rotate in the same direction.

[0035] Furthermore, when the left steering clutch 40L rotates forward while the left steering clutch 40R is engaged and the right steering clutch 40R is released, the rotation of the right output shaft 60R stops and the left output shaft 60L rotates, causing the bulldozer 1 to make a right pivot turn. However, when the bulldozer 1 makes a right pivot turn, the right steering brake 50R brakes the right output shaft 60R, as will be described later.

[0036] In this specification, pivot turning means turning around the crawler belt on the other side as an axis by rotating one of the left and right output shafts 60L, 60R while substantially or completely stopping the other.

[0037] As shown in FIG. 2, the right steering clutch 40R has a plurality of clutch plates 41, a plurality of clutch discs 42, and a clutch piston 43.

[0038] Each clutch plate 41 is attached to the right clutch gear 91R. Each clutch disc 42 is fixed to the right sun gear 33R. The clutch plates 41 and the clutch discs 42 are arranged alternately in the axial direction.

[0039] When the clutch piston 43 moves rightward in response to the supply of hydraulic oil, the clutch plates 41 and clutch discs 42 are pressed together, engaging the right steering clutch 40R. This brings the right sun gear 33R of the right planetary gear mechanism 30R and the right clutch gear 91R of the motor power transmission unit 90 into engagement.

[0040] On the other hand, when the clutch piston 43 moves leftward as the hydraulic oil is discharged, the clutch plates 41 and the clutch discs 42 separate, and the right steering clutch 40R is released. As a result, the right sun gear 33R of the right planetary gear mechanism 30R and the right clutch gear 91R of the motor power transmission unit 90 separate from each other.

[0041] The left steering clutch 40L has the same configuration as the right steering clutch 40R.

[0042] [Steering brake] The left and right steering brakes 50L, 50R are driven by the supply of hydraulic oil. The left and right steering brakes 50L, 50R are configured as wet multi-plate clutches that can be engaged and disengaged. In this embodiment, the left and right steering brakes 50L, 50R are negative-type hydraulic brakes. The left and right steering brakes 50L, 50R are fully engaged when no hydraulic oil is supplied, partially engaged when the hydraulic pressure of the supplied hydraulic oil is below a predetermined value, and disengaged when the hydraulic pressure of the supplied hydraulic oil is equal to or higher than the predetermined value. When the left and right steering brakes 50L, 50R are engaged (fully engaged or partially engaged), braking force is generated in the left and right steering brakes 50L, 50R.

[0043] The hydraulic pressure of the hydraulic oil supplied to the left and right steering brakes 50L, 50R is controlled by left and right brake control valves 28L, 28R. The left and right brake control valves 28L, 28R are driven in response to brake hydraulic pressure commands input from a controller 110.

[0044] The left and right steering brakes 50L, 50R brake the rotation of the left and right output shafts 60L, 60R.

[0045] Specifically, when the left steering brake 50L is engaged, the rotation of the left output shaft 60L is braked, thereby reducing the rotation of the left sprocket 2L. On the other hand, when the right steering brake 50R is engaged, the rotation of the right output shaft 60R is braked, thereby reducing the rotation of the right sprocket 2R.

[0046] As shown in FIG. 2, the right steering brake 50R includes a rotating member 51, a brake housing 52, a plurality of fixed plates 53, a plurality of brake discs 54, and a brake piston 55.

[0047] The rotating member 51 is fixed to the right output shaft 60R and rotates together with the right output shaft 60R. The brake housing 52 is fixed to the rotating member 51. Each fixed plate 53 is attached to the brake housing 52. Each brake disc 54 is fixed to the rotating member 51. The each fixed plate 53 and each brake disc 54 are arranged alternately in the axial direction.

[0048] When the brake piston 55 moves leftward as hydraulic oil is filled, the fixed plates 53 and the brake discs 54 separate, releasing the right steering brake 50R. On the other hand, when the brake piston 55 moves rightward as hydraulic oil is discharged, the fixed plates 53 and the brake discs 54 are pressed together, generating a braking force in the right steering brake 50R.

[0049] The left steering brake 50L has the same configuration as the right steering brake 50R.

[0050] [Slewing motor] The swing motor 80 is rotated by pressurized oil discharged from a variable displacement pump 101 driven by the power of the engine 10. The swing motor 80 rotates in either a forward rotation direction or a reverse rotation direction. The rotation direction and rotation speed of the swing motor 80 are controlled by a controller 110. The rotation speed of the swing motor 80 varies from 0% to 100% (maximum value) depending on the power transmitted from the engine 10.

[0051] The rotational power of the swing motor 80 is transmitted to the left and right steering clutches 40L, 40R via a motor power transmission unit 90. The swing motor 80 is used to generate a rotation speed difference between the left and right output shafts 60L, 60R. In this embodiment, the swing motor 80 rotates the left and right steering clutches 40L, 40R so as to generate a rotation speed difference between the left and right output shafts 60L, 60R. For example, when the bulldozer 1 swings to the right, the swing motor 80 rotates the left and right steering clutches 40L, 40R so that the rotation speed of the left output shaft 60L is higher than the rotation speed of the right output shaft 60R.

[0052] [Motor power transmission section] The motor power transmission unit 90 is disposed between the swing motor 80 and the left and right steering clutches 40L, 40R. The motor power transmission unit 90 transmits the rotational power of the swing motor 80 to the left and right steering clutches 40L, 40R.

[0053] The motor power transmission unit 90 includes left and right clutch gears 91L and 91R, a first transfer gear 92, a countershaft 93, a second transfer gear 94, an idler gear 95, and a pinion gear 96.

[0054] The left and right clutch gears 91L, 91R can be engaged with and disengaged from 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 can rotate around the axial direction of the input shaft 26. The left clutch gear 91L meshes with an idler gear 95. The right clutch gear 91R is connected to the idler gear 95 via a first transfer gear 92, a countershaft 93, and a second transfer gear 94. When the swing motor 80 rotates, the left and right clutch gears 91L, 91R rotate in opposite directions.

[0055] The idler gear 95 meshes with the left clutch gear 91L, the second transfer gear 94, and the pinion gear 96. The idler gear 95 is rotatable around the axial direction of the input shaft 26.

[0056] The pinion gear 96 meshes with the idler gear 95. The pinion gear 96 is rotatable about a pinion shaft 96a. The pinion gear 96 is rotated by the rotational power of the swing motor 80 transmitted via the pinion shaft 96a.

[0057] [Hydraulic supply unit] The hydraulic pressure supply unit 100 supplies hydraulic oil to the angle cylinder 8, the lifting cylinder 9, and the swing motor 80. The hydraulic pressure supply unit 100 includes a variable displacement pump 101 and a control valve .

[0058] The variable displacement pump 101 is an example of a "hydraulic pump" according to the present disclosure. The variable displacement pump 101 is connected to the power take-off device 21. The variable displacement pump 101 is driven by the power of the engine 10 transmitted from the power take-off device 21.

[0059] The variable displacement pump 101 discharges hydraulic oil to the control valve 102. The discharge amount from the variable displacement pump 101 is changed according to the tilt angle of a swash plate provided in the variable displacement pump 101. The tilt angle of the swash plate is controlled by a controller 110.

[0060] The control valve 102 is connected via pipes to the variable displacement pump 101, the angle cylinder 8, the lifting cylinder 9, and the swing motor 80. The control valve 102 distributes the hydraulic oil discharged from the variable displacement pump 101 to each of the variable displacement pump 101, the angle cylinder 8, and the lifting cylinder 9.

[0061] The amount of hydraulic oil supplied from the control valve 102 to the angle cylinder 8 is changed according to the position of the angle cylinder spool provided in the control valve 102. The amount of hydraulic oil supplied from the control valve 102 to the lift cylinder 9 is changed according to the position of the lift cylinder spool provided in the control valve 102. The amount of hydraulic oil supplied from the control valve 102 to the swing motor 80 is changed according to the position of the swing motor spool provided in the control valve 102. The positions of the angle cylinder spool, the lift cylinder spool, and the swing motor spool are controlled by a controller 110.

[0062] [controller] The controller 110 controls the rotation speed of the engine 10 and the speed stage clutch and direction stage clutch of the transmission 23 in order to make the bulldozer 1 travel.

[0063] The controller 110 is connected to a work equipment lever 35 used to drive the blade 6. The work equipment lever 35 includes an angle lever for tilting the blade 6 in the forward and backward directions, and a lifting lever for raising and lowering the blade 6 in the up and down directions. The controller 110 outputs control signals to the variable displacement pump 101 and the control valve 102 according to the amount and direction of operation of the work equipment lever 35.

[0064] The controller 110 is connected to the steering lever 36 used to steer the bulldozer 1. The controller 110 outputs control signals to the left and right clutch control valves 27L, 27R, the left and right brake control valves 28L, 28R, the variable displacement pump 101, and the control valve 102 in accordance with the amount of operation of the steering lever 36.

[0065] The steering lever 36 can be operated in a left turning direction P2 and a right turning direction P3 with respect to a neutral position P1. The controller 110 controls the left and right steering clutches 40L, 40R, the left and right steering brakes 50L, 50R, and the turning motor 80 according to the direction and amount of operation of the steering lever 36, thereby causing the bulldozer 1 to travel in one of a "straight mode," a "gentle turning mode," or a "pivot turning mode."

[0066] When the operation amount of the steering lever 36 is equal to or less than the first predetermined amount TH1, the controller 110 moves the bulldozer 1 straight in the straight-ahead mode. When the operation amount of the steering lever 36 is greater than the first predetermined amount TH1 and less than the second predetermined amount TH2, the controller 110 turns the bulldozer 1 in the gentle turn mode. When the operation amount of the steering lever 36 is equal to or greater than the second predetermined amount TH2, the controller 110 turns the bulldozer 1 in the pivot turn mode.

[0067] The second predetermined amount TH2 is greater than the first predetermined amount TH1. The first and second predetermined amounts TH1 and TH2 can be set to desired values. The first predetermined amount TH1 may be "0."

[0068] Straight line mode In the straight ahead mode, the controller 110 controls the left and right clutch control valves 27L, 27R to fully engage the left and right steering clutches 40L, 40R.

[0069] In the straight ahead mode, the controller 110 controls the left and right brake control valves 28L, 28R to release the left and right steering brakes 50L, 50R.

[0070] In the straight ahead mode, the controller 110 stops the swing motor 80 .

[0071] Gentle turning mode In the gentle turning mode, the controller 110 controls the left and right clutch control valves 27L, 27R to engage (typically, fully engage) the left and right steering clutches 40L, 40R.

[0072] In the gentle turning mode, the controller 110 controls the left and right brake control valves 28L, 28R to release the left and right steering brakes 50L, 50R.

[0073] In the gentle turning mode, the controller 110 controls the inner output shaft 60 as the operation amount of the steering lever 36 increases. IN The rotation speed of the outer output shaft is 60 OUT The rotation motor 80 is driven so that the rotation speed is lower than that of the rotation speed of the swivel motor 80.

[0074] Inner output shaft 60 IN The outer output shaft 60 is the output shaft of the left and right output shafts 60L, 60R that corresponds to the operation direction of the steering lever 36 (i.e., the turning direction). OUT This refers to the output shaft of the left and right output shafts 60L, 60R that is opposite to the operating direction of the steering lever 36.

[0075] The controller 110 increases the rotation speed of the swing motor 80 as the amount of operation of the steering lever 36 increases. For example, the controller 110 may gradually increase the rotation speed of the swing motor 80 in proportion to the amount of operation of the steering lever 36, or may increase the rotation speed of the swing motor 80 in stages according to the amount of operation of the steering lever 36.

[0076] The rotation speed of the swing motor 80 when the operation amount of the steering lever 36 is the second predetermined amount TH2 is not particularly limited as long as it is sufficiently high, but 90% or more is preferable, 95% or more is more preferable, and 100% (maximum value) is particularly preferable.

[0077] Pivot turn mode In the pivot turn mode, the controller 110 controls the left and right clutch control valves 27L, 27R to operate the inside steering clutch 40. IN releases the outer steering clutch 40 OUT are engaged (typically fully engaged).

[0078] Inner steering clutch 40 IN The outer steering clutch 40 is one of the left and right steering clutches 40L, 40R that corresponds to the operating direction of the steering lever 36. OUT This refers to the steering clutch of the left and right steering clutches 40L, 40R that is opposite to the operating direction of the steering lever 36.

[0079] In the pivot turn mode, the controller 110 controls the left and right brake control valves 28L, 28R to apply the inside steering brake 50. IN brake the outside steering brake 50 OUT Release it.

[0080] Inside steering brake 50 IN The outer steering brake 50 is one of the left and right steering brakes 50L, 50R that corresponds to the operating direction of the steering lever 36. OUTThis refers to the steering brake of the left and right steering brakes 50L, 50R that is opposite to the operating direction of the steering lever 36.

[0081] In the pivot turn mode, the controller 110 maintains the rotation speed of the swing motor 80 at approximately the same level as the rotation speed in the gentle turn mode. The rotation speed of the swing motor 80 is not particularly limited as long as it is sufficiently high, but is preferably 90% or higher, more preferably 95% or higher, and particularly preferably 100%.

[0082] - Hydraulic oil volume control during turning When the controller 110 drives the work implement cylinder (at least one of the angle cylinder 8 and the lifting cylinder 9) while the swing motor 80 is rotating, it performs "hydraulic oil amount control" to reduce the amount of hydraulic oil supplied from the hydraulic supply unit 100 to the swing motor 80.

[0083] Specifically, the controller 110 outputs a control command to the control valve 102 to control the positions of the angle cylinder spool, the lift cylinder spool, and the swing motor spool, thereby reducing the amount of hydraulic oil supplied from the control valve 102 to the swing motor 80. In hydraulic oil amount control, the controller 110 controls the angle cylinder spool, the lift cylinder spool, and the swing motor spool to predetermined positions. During hydraulic oil amount control, the controller 110 does not supply more than a predetermined amount of hydraulic oil from the control valve 102 to the swing motor 80, even if the steering lever 36 is operated greatly by the operator.

[0084] This type of hydraulic oil amount control allows the bulldozer 1 to turn at a low speed, but it is possible to prevent a decrease in the operability (driving force and driving speed) of the blade 6 when the operator operates the work equipment lever 35.

[0085] The case where the swing motor 80 is rotating means the case where the bulldozer 1 is swinging in the gentle swing mode or the pivot swing mode.

[0086] In controlling the amount of hydraulic oil, the controller 110 preferably increases the amount of hydraulic oil supplied to the work equipment cylinder from the hydraulic pressure supply unit 100. This ensures the amount of hydraulic oil necessary to drive the work equipment cylinder, thereby improving the operability of the blade 6.

[0087] In controlling the amount of hydraulic oil, the controller 110 may set the amount of hydraulic oil supplied from the control valve 102 to the swing motor 80 to "0." As the amount of hydraulic oil supplied from the control valve 102 to the swing motor 80 approaches "0," the swing speed of the bulldozer 1 becomes slower, while the operability of the blade 6 can be further improved.

[0088] In this embodiment, the controller 110 detects the driving of the work implement cylinder in response to the tractive force of the bulldozer 1 exceeding a predetermined value.

[0089] In this way, the driving of the work equipment cylinder is detected in response to the tractive force of the bulldozer 1 exceeding a predetermined value, so that hydraulic oil amount control can be performed automatically without relying on the operation of the operator.

[0090] Although the method for calculating the tractive force of the bulldozer 1 is not particularly limited, the following three methods are preferable.

[0091] The first method is a method of calculating the tractive force based on the rotation speed of the engine 10. First, the output torque of the torque converter 22 is calculated from the torque converter characteristics of the torque converter 22 based on the ratio of the rotation speed of the output shaft of the torque converter 22 to the rotation speed of the engine 10. Next, the tractive force is calculated by multiplying the output torque of the torque converter 22 by the reduction ratio from the output shaft of the torque converter 22 to the drive wheels 3A.

[0092] The second method is to calculate the tractive force based on the drive torque of the drive wheel 3A. The drive torque of the drive wheel 3A can be obtained by a drive torque sensor attached to the drive wheel 3A. The drive torque of the drive wheel 3A varies depending on the tractive force of the bulldozer 1. Therefore, by using the relational expression between the drive torque and the tractive force, the tractive force can be calculated from the drive torque obtained by the drive torque sensor.

[0093] The third method is a method of calculating tractive force using a learning model. First, a learning model is constructed by having a computer learn the regularity of the drive torque of the drive wheels 3A relative to multiple sensor values ​​indicating the state of the bulldozer 1. Examples of sensor values ​​include, but are not limited to, the output speed of the transmission 23, the pressure of the swing motor 80, the speed of the crawler 2A, the inlet pressure of the torque converter 22, the outlet pressure of the torque converter 22, the pitch angle of the bulldozer 1, and the fuel injection amount of the engine 10. As described in the second method, the drive torque of the drive wheels 3A can be acquired by a drive torque sensor attached to the drive wheels 3A. Next, when the multiple sensor values ​​are input into the learning model, the drive torque of the drive wheels 3A is output. Then, as described in the second method, the tractive force can be calculated from the drive torque acquired by the learning model by using the relational expression between the drive torque and the tractive force.

[0094] 2. Second embodiment 4 is a schematic system configuration diagram of a power transmission system of a bulldozer 1a, which is an example of a track-type work machine. In FIG. 4, the same members as those shown in FIG. 3 are assigned the same numbers.

[0095] The bulldozer 1a according to the second embodiment differs from the bulldozer 1 according to the first embodiment in that it is equipped with a differential device 29 instead of the left and right planetary gear mechanisms 30L, 30R and the left and right steering clutches 40L, 40R. These differences will be mainly described below.

[0096] The bulldozer 1a is equipped with a differential gear 29. To the differential gear 29, an output shaft 23a of the transmission 23 and an output shaft 80a of the swing motor 80 are connected.

[0097] The differential 29 converts the rotation of the output shaft 23a of the transmission 23 into the rotation of each of the left and right output shafts 60L, 60R. The differential 29 incorporates a gear mechanism that can rotate the left and right output shafts 60L, 60R at different rotational speeds.

[0098] The differential 29 changes the relative rotational speed of the left and right output shafts 60L, 60R based on the rotational direction and rotational speed of the swing motor 80. When the output shaft 80a of the swing motor 80 rotates in one direction, the differential 29 rotates the left output shaft 60L faster than the right output shaft 60R. When the output shaft 80a of the swing motor 80 rotates in the opposite direction, the differential 29 rotates the right output shaft 60R faster than the left output shaft 60L.

[0099] In this way, the bulldozer 1a can turn left and right depending on the rotation direction of the swing motor 80, and the turning radius of the bulldozer 1a changes depending on the rotation speed of the swing motor 80. The rotation direction and rotation speed of the swing motor 80 are controlled by the controller 110.

[0100] The controller 110 controls the left and right brake control valves 28L, 28R and the control valve 102 according to the direction and amount of operation of the steering lever 36. When the amount of operation of the steering lever 36 is equal to or less than a first predetermined amount TH1, the controller 110 moves the bulldozer 1a straight. When the amount of operation of the steering lever 36 is greater than the first predetermined amount TH1 and less than a second predetermined amount TH2, the controller 110 rotates the swing motor 80 via the control valve 102 to turn the bulldozer 1a. When the amount of operation of the steering lever 36 is equal to or greater than the second predetermined amount TH2, the controller 110 rotates the swing motor 80 via the control valve 102 while applying one of the left and right steering brakes 50L, 50R via one of the left and right brake control valves 28L, 28R, to make a pivot turn of the bulldozer 1a.

[0101] In the bulldozer 1a according to the second embodiment, as described in the first embodiment, the controller 110 also executes hydraulic oil amount control to reduce the amount of hydraulic oil supplied from the hydraulic pressure supply unit 100 to the swing motor 80 when driving the work equipment cylinder while the swing motor 80 is rotating. This makes it possible to prevent the operability of the blade 6 from decreasing.

[0102] In controlling the amount of hydraulic oil, the controller 110 preferably increases the amount of hydraulic oil supplied to the work equipment cylinder from the hydraulic pressure supply unit 100. This ensures the amount of hydraulic oil necessary to drive the work equipment cylinder, thereby improving the operability of the blade 6.

[0103] (Modification of the embodiment) The present invention is not limited to the above-described embodiments, and various modifications and alterations are possible without departing from the scope of the present invention.

[0104] (Variation 1) In the above first and second embodiments, a bulldozer has been used as an example of a track-type working machine, but the present invention is widely applicable to track-type working machines having track-type traveling devices, such as hydraulic excavators.

[0105] (Variation 2) In the first and second embodiments, a blade has been described as an example of a work implement, but the present invention is not limited to this. Examples of work implements include a ripper used for crushing work and excavation work.

[0106] (Variation 3) In the first and second embodiments, the hydraulic pressure supply unit 100 has the variable displacement pump 101 and the control valve 102, but is not limited to this. For example, as shown in Fig. 5, the hydraulic pressure supply unit 100 may separately have a swing motor hydraulic pump 103 that supplies hydraulic oil to the swing motor 80, and a work machine hydraulic pump 104 that supplies hydraulic oil to the angle cylinder 8 and the lift cylinder 9. In this case, the controller 110 can control the amount of hydraulic oil by controlling the swash plate of the swing motor hydraulic pump 103 to reduce the amount of hydraulic oil supplied from the swing motor hydraulic pump 103 to the swing motor 80, and by increasing the amount of hydraulic oil supplied from the work machine hydraulic pump 104 to the angle cylinder 8 and the lift cylinder 9 via the control valve 105.

[0107] (Variation 4) In the first and second embodiments, the left and right steering clutches 40L, 40R are positive type hydraulic clutches, but they may also be negative type hydraulic clutches.

[0108] (Variation 5) In the first and second embodiments, the left and right steering brakes 50L, 50R are negative type hydraulic brakes, but they may also be positive type hydraulic brakes.

[0109] (Variation 6) In the first and second embodiments, the controller 110 detects the driving of the work implement cylinder in response to the tractive force of the bulldozer 1 exceeding a predetermined value, but the present invention is not limited to this.

[0110] For example, as shown in FIG. 6 , if the bulldozer 1 is equipped with a work implement priority switch 37, the controller 110 may detect the actuation of the work implement cylinder in response to the work implement priority switch 37 being turned on. The work implement priority switch 37 is connected to the controller 110. When the operator operates the work implement lever 35 to actuate the work implement cylinder while the bulldozer 1 is swinging, the operator turns the work implement priority switch 37 on. The operator may turn the work implement priority switch 37 on before operating the work implement lever 35, or may turn the work implement priority switch 37 on while operating the work implement lever 35. The controller 110 detects the actuation of the work implement cylinder in response to the work implement priority switch 37 being turned on. Therefore, hydraulic oil amount control can be executed at a desired timing based on the operator's intention.

[0111] Furthermore, the controller 110 may detect the actuation of the work implement cylinder in response to the operation of the work implement lever 35. In this case, the actuation of the work implement cylinder is detected in response to the operation of the work implement lever 35 by the operator, which is simple and eliminates the need to calculate traction force or provide a work implement priority switch 37.

[0112] (Variation 7) In the first and second embodiments, the controller 110 switches from the gentle turn mode to the pivot turn mode when the operation amount of the steering lever 36 becomes equal to or greater than the second predetermined amount TH2, but this is not limited to this. The controller 110 may also switch from the gentle turn mode to the pivot turn mode when the operation amount of the steering lever 36 is greater than the first predetermined amount TH1 and the operator turns on the pivot turn button. [Explanation of symbols]

[0113] 1,1a Bulldozer 10 Engine 20 Engine power transmission section 26 Input shaft 29 Differential gear 30L, 30R left and right planetary gear mechanism 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 Swing motor 90 Motor power transmission section 100 Hydraulic supply unit 110 Controller

Claims

1. Left and right steering brakes that brake the left and right output shafts; a rotation motor that generates a difference in rotation speed between the left and right output shafts; a work machine cylinder that drives a work machine attached to the vehicle body; a hydraulic pressure supply unit that supplies hydraulic oil to each of the swing motor and the work machine cylinder; a controller for controlling the hydraulic pressure supply unit; Equipped with the controller executes hydraulic oil amount control to reduce the amount of hydraulic oil supplied from the hydraulic pressure supply unit to the swing motor when driving the work machine cylinder while the swing motor is rotating. Tracked work machine.

2. The hydraulic pressure supply unit includes a hydraulic pump that is driven by engine power and discharges hydraulic oil, and a control valve that distributes the hydraulic oil discharged from the hydraulic pump to each of the swing motor and the work machine cylinder, The controller reduces the amount of hydraulic oil supplied from the control valve to the swing motor in the hydraulic oil amount control.

2. The track-type work machine according to claim 1.

3. the hydraulic pressure supply unit includes a swing motor hydraulic pump that supplies hydraulic oil to the swing motor, and a work machine hydraulic pump that supplies hydraulic oil to the work machine cylinder, The controller reduces the amount of hydraulic oil supplied from the swing motor hydraulic pump to the swing motor in the hydraulic oil amount control.

2. The track-type work machine according to claim 1.

4. The controller increases the amount of hydraulic oil supplied from the hydraulic pressure supply unit to the work machine cylinder in the hydraulic oil amount control.

4. A track-type working machine according to claim 1.

5. Further equipped with a work equipment priority switch, The controller detects the driving of the work machine cylinder in response to the work machine priority switch being turned on.

5. A track-type working machine according to claim 1.

6. the controller detects the actuation of the work implement cylinder in response to a tractive force of the track-type work machine exceeding a predetermined value.

5. A track-type working machine according to claim 1.

7. Further provided is a work machine lever for operating the work machine, The controller detects the actuation of the work implement cylinder in response to the operation of the work implement lever.

5. A track-type working machine according to claim 1.

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