Patent Application
20250012043
The present disclosure relates to a crawler-type work machine.
A crawler-type work machine (for example, a bulldozer) that is able to turn to the left and right by using a turning motor is known in the prior art (see US 2020/0247468).
While a situation in which a crawler-type work machine is provided with a work implement is not discussed in US 2020/0247468, when a crawler-type work machine is provided with a work implement, there is a possibility that the amount of hydraulic fluid that can be distributed to the work implement may be insufficient and the operability of the work implement may deteriorate when a hydraulic pressure supply unit for the turning motor is also used for the work implement.
An object of the present disclosure is to provide a crawler-type work machine with which a reduction in the operability of the work implement can be suppressed.
A crawler-type work machine according to one aspect of the present disclosure comprises left and right steering brakes, a turning motor, work implement cylinders, a hydraulic pressure supply unit, and a controller. The left and right steering brakes are configured to brake left and right output shafts. The turning motor is configured to produce a rotation speed difference between the left and right output shafts. The work implement cylinders are configured to drive a work implement attached to the vehicle body. The hydraulic pressure supply unit is configured to supply hydraulic fluid to the turning motor and the work implement cylinders. The controller controls the hydraulic pressure supply unit. The controller is configured to execute a hydraulic fluid amount control for reducing the hydraulic fluid amount supplied from the hydraulic pressure supply unit to the turning motor when the work implement cylinders are driven while the turning motor is rotating.
According to the feature of the present disclosure, there can be provided a crawler-type work machine with which a reduction in the operability of the work implement can be suppressed.
As illustrated in
The vehicle body 2 has a cab 4, an engine room 5, and a vehicle body frame (not illustrated). The cab 4 is disposed in a rear upper part of the vehicle body 2. The engine room 5 is disposed in front of the cab 4.
The work implement 3 is attached to the vehicle body 2. The work implement 3 has a blade 6, a frame 7, angle cylinders 8, and lift cylinders 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 surfaces of the vehicle body 2.
The blade 6 is driven by the angle cylinders 8 and the lift cylinders 9. The angle cylinders 8 and the lift cylinders 9 are each examples of “work implement cylinders” according to the present disclosure.
The front ends of the angle cylinders 8 are rotatably supported on the rear surface of the blade 6. The rear ends of the angle cylinders 8 are rotatably supported on the side surfaces of the vehicle body 2. The blade 6 tilts in the front-back direction due to the extension and contraction of the angle cylinders 8 by hydraulic pressure.
The lower ends of the lift cylinders 9 are rotatably supported on the upper surface of the frame 7. The middle sections of the lift cylinders 9 are rotatably supported on the side surfaces of the vehicle body 2. The blade 6 moves in the up-down direction due to the extension and contraction of the angle cylinders 9 by hydraulic pressure.
The pair of left and right crawler belt devices 1A are travel devices of the bulldozer 1. The pair of left and right crawler belt devices 1A are disposed on both sides of the vehicle body 2.
Each of the pair of left and right crawler belt devices 1A has a crawler belt 2A, a drive wheel (sprocket) 3A, an idler wheel (idler) 4A, and a track frame 5A.
The crawler belt 2A is configured in an annular shape (endless shape) and is wound onto the drive wheel 3A and the idler wheel 4A. The crawler belt 2A meshes with the drive wheel 3A and rotates due to the rotational power of the drive wheel 3A.
The drive wheel 3A and the track frame 5A are both attached to a side section of the vehicle body 2. The drive wheel 3A is disposed so as to allow for rotational driving at the rear of the track frame 5A. The left and right pair of drive wheels 3A are supported by belowmentioned left and right output shafts 60L, 60R. The idler wheel 4A is rotatably disposed at a front end section of the track frame 5A.
As illustrated in
The engine power transmitting section 20 transmits power from the engine 10 to the left and right planetary gear mechanisms 30L, 30R. The engine power transmitting section 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.
The power take-off device 21 distributes the power of the engine 10 to the torque converter 22 and a belowmentioned variable capacity pump 101. The torque converter 22 transmits the power of the engine 10 transmitted by the power take-off device 21 to the transmission 23 by means of a fluid. The transmission 23 has a plurality of velocity stage clutches for changing the rotation power transmitted from the torque converter 22, and a direction stage clutch for switching between forward travel and reverse travel. The transmission 23 is coupled to the pinion 24. The power from the transmission 23 is transmitted through the pinion 24 and the bevel gear 25 to the input shaft 26. The input shaft 26 extends in the left-right direction. The axial direction of the input shaft 26 has the same meaning as the left-right direction of the bulldozer 1.
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 respectively 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.
The left and right ring gears 31L, 31R are coupled to the input shaft 26. The left and right planetary gears 32L, 32R are respectively disposed on the inside of 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 respectively 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 respectively disposed on the inside of the left and right planetary gears 32L, 32R in the radial direction. The left and right sun gears 33L, 33R are respectively coupled to the left and right steering clutches 40L, 40R. The left and right sun gears 33L, 33R are able to separate from the motor power transmitting section 90 (specifically, belowmentioned left and right clutch gears 91L, 91R) by means of the left and right steering clutches 40L, 40R. The left and right carriers 34L, 34R are respectively coupled to the left and right planetary gears 32L, 32R and the left and right output shafts 60L, 60R.
The left and right steering clutches 40L, 40R are respectively disposed between the left and right planetary gear mechanisms 30L, 30R and the motor power transmitting section 90. The left and right steering clutches 40L, 40R respectively disengage from the left and right sun gears 33L, 33R of the left and right planetary gear mechanisms 30L, 30R and from the left and right clutch gears 91L, 91R of the motor power transmitting section 90.
The left and right steering clutches 40L, 40R are driven by the supply of hydraulic fluid. The left and right steering clutches 40L, 40R are configured by wet multiplate clutches that can be engaged and disengaged. 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 disengaged when hydraulic fluid is not supplied, are partially engaged when the pressure of the supplied hydraulic fluid is less than a predetermined value, and are completely engaged when the pressure of the supplied hydraulic fluid is equal to or greater than the predetermined value.
The pressure of the hydraulic fluid supplied to the left and right steering clutches 40L, 40R is controlled by the 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 instruction inputted from the controller 110.
The left and right steering clutches 40L, 40R switch between transmitting and blocking the rotational power from the input shaft 26 to the respective left and right output shafts 60L, 60R by means of the respective left and right planetary gear mechanisms 30L, 30R.
Specifically, the rotation of the input shaft 26 is transmitted through the left ring gear 31L, the left planetary gear 32L, and the left carrier 34L to the left output shaft 60L when the left steering clutch 40L is engaged. Conversely, when the left steering clutch 40L is disengaged, the left sun gear 33L enters a freely rotating state and the transmission of the rotation power from the input shaft 26 to the left output shaft 60L is blocked. Similarly, the transmission or blocking of the rotational power from the input shaft 26 to the right output shaft 60R is switched in response to the engagement or disengagement of the right steering clutch 40R.
The left and right steering clutches 40L, 40R are able to rotate about the input shaft 26. The left and right steering clutches 40L, 40R rotate in mutually opposite directions due to the rotational power from the turning motor 80 being transmitted through the motor power transmitting section 90.
For example, when the right steering clutch 40R rotates in reverse while the left steering clutch 40L rotates in the forward direction while the left and right steering clutches 40L, 40R are engaged, the rotation speed of the left output shaft 60L increases more than the rotation speed of the right output shaft 60R and the bulldozer 1 turns slowly to the right.
In the present description, slow turning signifies that forward travel or reverse travel occurs such that an arc is drawn with a relatively large turning radius due to the rotation speed difference being produced between the left and right output shafts 60L, 60R that rotate in the same direction.
In addition, when the left steering clutch 40L rotates in the forward direction while the left steering clutch 40L is engaged and the right steering clutch 40R is disengaged, the rotation of the right output shaft 60R is stopped and the left output shaft 60L rotates whereby the bulldozer 1 makes a pivot turn to the right. However, when the bulldozer 1 makes a pivot turn to the right, the right steering brake 50R brakes the right output shaft 60R as discussed below.
In the present description, a pivot turn signifies turning using the crawler belt on the other side as an axis due to one of the left and right output shafts 60L, 60R being substantially or completely stopped while the other is rotating.
As illustrated in
The clutch plates 41 are attached to a right clutch gear 91R. The clutch disks 42 are fixed to the right sun gear 33R. The clutch plates 41 and the clutch disks 42 are disposed alternately in the axial direction.
When the clutch piston 43 moves in the right direction accompanying the supply of hydraulic fluid, the clutch plates 41 and the clutch disks 42 are pressed together and the right steering clutch 40R is engaged. Consequently, the right sun gear 33R of the right planetary gear mechanism 30R and the right clutch gear 91R of the motor power transmitting section 90 are joined together.
When the clutch piston 43 moves in the left direction accompanying the discharge of hydraulic fluid, the clutch plates 41 and the clutch disks 42 separate and the right steering clutch 40R is disengaged. Consequently, the right sun gear 33R of the right planetary gear mechanism 30R and the right clutch gear 91R of the motor power transmitting section 90 move away from each other.
The left steering clutch 40L has the same configuration as the right steering clutch 40R.
The left and right steering brakes 50L, 50R are driven by the supply of hydraulic fluid. The left and right steering brakes 50L, 50R are configured by wet multiplate clutches that can be engaged and disengaged. In the present embodiment, the left and right steering brakes 50L, 50R are negative-type hydraulic brakes. The left and right steering brakes 50L, 50R are completely engaged when hydraulic fluid is not supplied, are partially engaged when the pressure of the supplied hydraulic fluid is less than a predetermined value, and are disengaged when the pressure of the supplied hydraulic fluid is equal to or greater than the predetermined value. When the left and right steering brakes 50L, 50R are engaged (complete engagement or partial engagement), a braking force is produced on the left and right steering brakes 50L, 50R.
The pressure of the hydraulic fluid 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 a brake hydraulic pressure instruction inputted from the controller 110.
The left and right steering brakes 50L, 50R respectively brake the rotation of the left and right output shafts 60L, 60R.
Specifically, when the left steering brake 50L is engaged, braking is applied to the rotation of the left output shaft 60L whereby the rotation of the left sprocket 2L is reduced. Conversely, when the right steering brake 50R is engaged, braking is applied to the rotation of the right output shaft 60R whereby the rotation of the right sprocket 2R is reduced.
As illustrated in
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 to the rotating member 51. The fixing plates 53 are attached to the brake housing 52. The brake disks 54 are fixed to the rotating member 51. The fixing plates 53 and the brake disks 54 are disposed alternately in the axial direction.
When the brake piston 55 moves in the left direction accompanying the filling of hydraulic fluid, the fixing plates 53 and the brake disks 54 separate and the right steering brake 50R is disengaged. Conversely, when the brake piston 55 moves in the right direction accompanying the discharge of hydraulic fluid, the fixing plates 53 and the brake disks 54 are pressed together and the braking force of the right steering brake 50R is produced.
The left steering brake 50L has the same configuration as the right steering brake 50R.
The turning motor 80 rotates due to pressure oil discharged from the variable capacity pump 101 driven by power from the engine 10. The turning motor 80 rotates in the forward rotating direction and the reverse rotating direction. The rotating direction and the rotation speed of the turning motor 80 are controlled by the controller 110. The rotation speed of the turning motor 80 changes from 0% to 100% (maximum value) in accordance with the power transmitted from the engine 10.
The rotation power of the turning motor 80 is transmitted through the motor power transmitting section 90 to the left and right steering clutches 40L, 40R. The turning motor 80 is used for producing a rotation speed difference between the left and right output shafts 60L, 60R. In the present embodiment, the turning motor 80 causes the left and right steering clutches 40L, 40R to rotate so that a rotation speed difference is produced between the left and right output shafts 60L, 60R. For example, when the bulldozer 1 turns slowly to the right, the turning motor 80 causes the left and right steering clutches 40L, 40R to rotate so that the rotation speed of the left output shaft 60L becomes higher than the rotation speed of the right output shaft 60R.
The motor power transmitting section 90 is disposed between the turning motor 80 and the left and right steering clutches 40L, 40R. The motor power transmitting section 90 transmits the rotational power of the turning motor 80 to the left and right steering clutches 40L, 40R.
The motor power transmitting section 90 has the left and right clutch gears 91L, 91R, a first transfer gear 92, an auxiliary shaft 93, a second transfer gear 94, an idler gear 95, and a pinion gear 96.
The left and right clutch gears 91L, 91R are able to separate from the left and right sun gears 33L, 33R by means of the left and right steering clutches 40L, 40R. The left and right clutch gears 91L, 91R are able to rotate about the axial direction of the input shaft 26. The left clutch gear 91L meshes with the idler gear 95. The right clutch gear 91R is coupled through the first transfer gear 92, the auxiliary shaft 93, and the second transfer gear 94 to the idler gear 95. The left and right clutch gears 91L, 91R rotate in opposite directions when the turning motor 80 rotates.
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 able to rotate about the axial direction of the input shaft 26.
The pinion gear 96 meshes with the idler gear 95. The pinion gear 96 is able to rotate about a pinion shaft 96a. The pinion gear 96 rotates due to the rotational power of the turning motor 80 that is transmitted through the pinion shaft 96a.
The hydraulic pressure supply unit 100 supplies hydraulic fluid to the angle cylinders 8, the lift cylinders 9, and the turning motor 80. The hydraulic pressure supply unit 100 has the variable capacity pump 101 and a control valve 102.
The variable capacity pump 101 is an example of a “hydraulic pump” according to the present disclosure. The variable capacity pump 101 is coupled to the power take-off device 21. The variable capacity pump 101 is driven by power from the engine 10 transmitted from the power take-off device 21.
The variable capacity pump 101 discharges hydraulic fluid to the control valve 102. The discharge amount from the variable capacity pump 101 is changed in accordance with the tilt angle of a skew plate provided inside the variable capacity pump 101. The tilt angle of the skew plate is controlled by the controller 110.
The control valve 102 is respectively connected to the variable capacity pump 101, the angle cylinders 8, the lift cylinders 9, and the turning motor 80 by means of pipes. The control valve 102 distributes hydraulic fluid discharged from the variable capacity pump 101 to the variable capacity pump 101, the angle cylinders 8, and the lift cylinders 9.
The amount of hydraulic fluid supplied from the control valve 102 to the angle cylinders 8 is changed in accordance with the position of an angle cylinder spool provided inside the control valve 102. The amount of hydraulic fluid supplied from the control valve 102 to the lift cylinders 9 is changed in accordance with the position of a lift cylinder spool provided inside the control valve 102. The amount of hydraulic fluid supplied from the control valve 102 to the turning motor 80 is changed in accordance with the position of a turning motor spool provided inside the control valve 102. The respective positions of the angle cylinder spool, the lift cylinder spool, and the turning motor spool are controlled by the controller 110.
The controller 110 controls the rotation speed of the engine 10 and the velocity stage clutches and the direction stage clutches of the transmission 23 in order to cause the bulldozer 1 to travel.
The controller 110 is connected to a work implement lever 35 used for a driving operation of the blade 6. An angle lever for tilting the blade 6 in the front-back direction and a lift lever for lifting the blade 6 in the up-down direction are included in the work implement lever 35. The controller 110 outputs control signals to the variable capacity pump 101 and the control valve 102 in response to the operating amount and the operating direction of the work implement lever 35.
The controller 110 is connected to a steering lever 36 used for steering operations of 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 capacity pump 101, and the control valve 102 in response to the operating amount of the steering lever 36.
The steering lever 36 can be operated in a left turning direction P2 or a right turning direction P3 using a neutral position P1 as a point of reference. 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 in response to the operating direction and the operating amount of the steering lever 36 thereby causing the bulldozer 1 to travel in any of a “straight travel mode,” a “slow turn mode,” and a “pivot turn mode.”
The controller 110 causes the bulldozer 1 to travel straight in the straight travel mode when the operating amount of the steering lever 36 is equal to or less than a first predetermined amount TH1. When the operating amount of the steering lever 36 is greater than the first predetermined amount TH1 and less than a second predetermined amount TH2, the controller 110 causes the bulldozer 1 to turn in the slow turn mode. When the operating amount of the steering lever 36 is equal to or greater than the second predetermined amount TH2, the controller 110 causes the bulldozer 1 to turn in the pivot turn mode.
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 even be zero.
In the straight travel mode, the controller 110 controls the left and right clutch control valves 27L, 27R to cause the left and right steering clutches 40L, 40R to completely engage.
In the straight travel mode, the controller 110 controls the left and right brake control valves 28L, 28R to cause the left and right steering brakes 50L, 50R to disengage.
In the straight travel mode, the controller 110 stops the turning motor 80.
In the slow turn mode, the controller 110 controls the left and right clutch control valves 27L, 27R to cause the left and right steering clutches 40L, 40R to engage (typically to be completely engaged).
In the slow turn mode, the controller 110 controls the left and right brake control valves 28L, 28R to cause the left and right steering brakes 50L, 50R to disengage.
In the slow turn mode, the controller 110 causes the turning motor 80 to be driven so that the rotation speed of an inside output shaft 60IN is lower than the rotation speed of an outside output shaft 60OUT in correspondence to an increase in the operating amount of the steering lever 36.
The inside output shaft 60IN is the output shaft corresponding to the operating direction (that is, the turning direction) of the steering lever 36 among the left and right output shafts 60L, 60R. The outside output shaft 60OUT is the output shaft opposite to the operating direction of the steering lever 36 among the left and right output shafts 60L, 60R.
The controller 110 increases the rotation speed of the turning motor 80 in correspondence to an increase in the operating amount of the steering lever 36. For example, the controller 110 may increase the rotation speed of the turning motor 80 gradually so as to be proportional to the operating amount of the steering lever 36, or may increase the rotation speed of the turning motor 80 in stages in response to the operating amount of the steering lever 36.
While the rotation speed of the turning motor 80 when the operating amount of the steering lever 36 is the second predetermined amount TH2 is not limited in particular so long as the value is sufficiently high, the rotation speed is preferably at least 90%, more preferably at least 95%, and most preferably 100% (maximum value).
In the pivot turn mode, the controller 110 controls the left and right clutch control valves 27L, 27R to cause an inside steering clutch 40IN to disengage and cause an outside steering clutch 40OUT to engage (typically to be completely engaged).
The inside steering clutch 40IN is the steering clutch corresponding to the operating direction of the steering lever 36 among the left and right steering clutches 40L, 40R. The outside steering clutch 40OUT is the steering clutch in the opposite direction to the operating direction of the steering lever 36 among the left and right steering clutches 40L, 40R.
In the pivot turn mode, the controller 110 controls the left and right brake control valves 28L, 28R to cause an inside steering brake 50IN to brake and cause an outside steering brake 50OUT to disengage.
The inside steering brake 50IN is the steering brake corresponding to the operating direction of the steering lever 36 among the left and right steering brakes 50L, 50R. The outside steering brake 50OUT is the steering brake in the opposite direction of the operating direction of the steering lever 36 among the left and right steering brakes 50L, 50R.
In the pivot turn mode, the controller 110 maintains the rotation speed of the turning motor 80 at about the same rotation speed as in the slow turn mode. While the rotation speed of the turning motor 80 is not limited in particular so long as the value is sufficiently high, the rotation speed is preferably at least 90%, more preferably at least 95%, and most preferably 100%.
When driving a work implement cylinder (at least one of the angle cylinders 8 and the lift cylinders 9) when rotating the turning motor 80, a “hydraulic fluid amount control” is executed for reducing the hydraulic fluid amount supplied from the hydraulic pressure supply unit 100 to the turning motor 80.
Specifically, the controller 110 outputs a control command to the control valve 102 to control the respective positions of the angle cylinder spool, the lift cylinder spool, and the turning motor spool thereby reducing the hydraulic fluid amount supplied from the control valve 102 to the turning motor 80. The controller 110 controls the angle cylinder spool, the lift cylinder spool, and the turning motor spool so as to be at previously set positions during the hydraulic fluid amount control. The controller 110 does not supply hydraulic fluid that exceeds a predetermined amount from the control valve 102 to the turning motor 80 even if the steering lever 36 is operated a large amount by the operator during the hydraulic fluid amount control.
According to such hydraulic fluid amount control, although the bulldozer 1 turns at a slow speed, a reduction in the operability (driving power and driving speed) of the blade 6 when the operator operates the work implement lever 35 can be suppressed.
The situation of the turning motor 80 being rotated signifies that the bulldozer 1 is turning in the slow turn mode or the pivot turn mode.
The controller 110 preferably increases the hydraulic fluid amount supplied from the hydraulic pressure supply unit 100 to the work implement cylinders in the hydraulic fluid amount control. As a result, the operability of the blade 6 can be improved because the hydraulic fluid amount necessary for driving the work implement cylinders can be assured.
The controller 110 may also set the hydraulic fluid amount supplied from the control valve 102 to the turning motor 80 to “0” in the hydraulic fluid amount control. While the turning speed of the bulldozer 1 decreases as the hydraulic fluid amount supplied from the control valve 102 to the turning motor 80 approaches “0,” the operability of the blade 6 may further improve.
In the present embodiment, the controller 110 detects the driving of the work implement cylinders in accordance with the tractive force of the bulldozer 1 exceeding a predetermined value.
Because the driving of the work implement cylinders can be detected in accordance with the tractive force of the bulldozer 21 exceeding a predetermined value in this way, the hydraulic fluid amount control can be executed automatically without relying on an operation by the operator.
While the method for deriving the tractive force of the bulldozer 1 is not limited in particular, the following three methods are preferred.
A first method is for deriving the tractive force on the basis of the rotation speed, etc., of the engine 10. Firstly, the output torque of the torque converter 22 is calculated from the torque converter characteristics of the torque converter 22 on the basis of the output shaft rotation speed of the torque converter 22 with respect to the rotation speed of the engine 10. Next, the tractive force is derived by multiplying the output torque of the torque converter 22 by a speed reduction ratio from the output shaft of the torque converter 22 to the drive wheels 3A.
A second method is for deriving the tractive force on the basis of the drive torque of the drive wheels 3A. The drive torque of the drive wheels 3A can be acquired by means of a drive torque sensor attached to the drive wheels 3A. The drive torque of the drive wheels 3A fluctuates in accordance with the tractive force of the bulldozer 1. Consequently, by using a relational expression of the drive torque and the tractive force, the tractive force can be derived from the drive torque acquired by means of the drive torque sensor.
A third method is for deriving the tractive force by using a learning model. Firstly, a learning model is constructed by causing a computer to learn drive torque regularities of the drive wheels 3A with respect to a plurality of sensor values that indicate states of the bulldozer 1. The sensor values may include, but are not limited to, the output rotation speed of the transmission 23, the force of the turning motor 80, the rotation speed of the crawler belt 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. The drive torque of the drive wheels 3A can be acquired by means of a drive torque sensor attached to the drive wheels 3A as explained in the second method. Next, the plurality of sensor values are inputted to the learning model and the drive torque of the drive wheels 3A is outputted. Consequently, by using a relational expression of the drive torque and the tractive force as explained in the second method, the tractive force can be derived from the drive torque acquired by means of machine learning.
The bulldozer 1a according to the second embodiment is provided with a differential gear 29 instead of the left and right planetary gear mechanisms 30L, 30R and the left and right steering clutches 40L, 40R and thus differs from the bulldozer 1 according to the first embodiment. The above difference will mainly be explained hereinbelow.
The bulldozer 1a comprises the differential gear 29. An output shaft 23a of the transmission 23 and an output shaft 80a of the turning motor 80 are coupled to the differential gear 29.
The differential gear 29 converts the rotation of the output shaft 23a of the transmission 23 to the rotations of the left and right output shafts 60L, 60R. The differential gear 29 contains therein a gear mechanism that is able to cause the left and right output shafts 60L, 60R to rotate at different rotation speeds.
The differential gear 29 changes the relative rotation speeds of the left and right output shafts 60L, 60R on the basis of the rotating direction and the rotation speed of the turning motor 80. The differential gear 29 causes the left output shaft 60L to rotate faster than the right output shaft 60R when the output shaft 80a of the turning motor 80 is rotating in one direction. The differential gear 29 causes the right output shaft 60R to rotate faster than the left output shaft 60L when the output shaft 80a of the turning motor 80 is rotating in the opposite direction.
In this way, the bulldozer 1a is able to turn to the right or left in accordance with the rotating direction of the turning motor 80 and the turning radius of the bulldozer 1a can be changed in accordance with the rotation speed of the turning motor 80. The rotating direction and the rotation speed of the turning motor 80 are controlled by the controller 110.
The controller 110 controls the left and right brake control valves 28L, 28R and the control valve 102 in response to the operating direction and the operating amount of the steering lever 36. The controller 110 causes the bulldozer 1a to travel straight when the operating amount of the steering lever 36 is equal to or less than a first predetermined amount TH1. When the operating amount of the steering lever 36 is greater than the first predetermined amount TH1 and less than a second predetermined amount TH2, the controller 110 causes the bulldozer 1a to turn due to the rotation of the turning motor 80 via the control valve 102. When the operating amount of the steering lever 36 is equal to or greater than the second predetermined amount TH2, the controller 110 causes the bulldozer 1a to pivot turn by braking one of the left and right steering brakes 50L, 50R via one of the left and right brake control valves 28L, 28R while rotating the turning motor 80 via the control valve 102.
Even in the bulldozer 1a according to the second embodiment, when the work implement cylinders are driven when the turning motor 80 is being rotated, the controller 110 performs a hydraulic fluid amount control to reduce the hydraulic fluid amount supplied from the hydraulic pressure supply unit 100 to the turning motor 80 as explained above in the first embodiment. Consequently, a reduction in the operability of the blade 6 can be suppressed.
The controller 110 preferably increases the hydraulic fluid amount supplied from the hydraulic pressure supply unit 100 to the work implement cylinders during the hydraulic fluid amount control. As a result, the operability of the blade 6 can be improved because the hydraulic fluid amount necessary for driving the work implement cylinders can be assured.
The present invention is not limited to the above embodiments and various changes and modifications may be made without departing from the spirit of the invention.
While a bulldozer is provided as an example of the crawler-type work machine in the first and second embodiments, the present invention can be widely applied to a crawler-type work machine having a crawler-type travel device such as a hydraulic excavator.
While a blade is provided as an example of the work implement in the first and second embodiments, the present invention is not limited thereto. For example, a ripper used for crushing work or excavating work can be provided as an example of the work implement.
The hydraulic pressure supply unit 100 in the first and second embodiments has the variable capacity pump 101 and the control valve 102, but is not limited thereto. For example as illustrated in
While the left and right steering clutches 40L, 40R are positive-type hydraulic clutches in the first and second embodiments, the left and right steering clutches 40L, 40R may also be negative-type hydraulic clutches.
While the left and right steering brakes 50L, 50R are negative-type hydraulic brakes in the above first and second embodiments, the left and right steering brakes 50L, 50R may also be positive-type hydraulic brakes.
While the controller 110 detects the driving of the work implement cylinders in accordance with the tractive force of the bulldozer 1 exceeding a predetermined value in the first and second embodiments, the present invention is not limited thereto.
For example as illustrated in
Moreover, the controller 110 may detect the driving of the work implement cylinders in accordance with the work implement lever 35 being operated. In this case, because the driving of the work implement cylinders is detected in accordance with the work implement lever 35 being operated by the operator, convenience is achieved because there is no need to calculate the tractive force or provide the work implement priority switch 37.
While the controller 110 in the first and second embodiments switches from the slow turn mode to the pivot turn mode in response to the operating amount of the steering lever 36 becoming equal to or greater than the second predetermined amount TH2, the present invention is not limited thereto. The controller 110 may switch from the slow turn mode to the pivot turn mode when the operating amount of the steering lever 36 is greater than the first predetermined amount TH1 and when the operator has switched a pivot turning button to the ON-state.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-014810 | Feb 2022 | JP | national |
This application is a U.S. National stage application of International Application No. PCT/JP2022/048256, filed on Dec. 27, 2022. This U.S. National stage application claims priority under 35 U.S.C. § 119 (a) to Japanese Patent Application No. 2022-014810, filed in Japan on Feb. 2, 2022, the entire contents of which are hereby incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/048256 | 12/27/2022 | WO |
