JP6483599B2 - Working machine - Google Patents

Description

  The present invention relates to a working machine such as a skid steer loader or a compact truck loader.

  Conventionally, in a working machine such as a skid steer loader or a compact truck loader, a technique shown in Patent Document 1 is known as a technique for preventing engine stall. In the working machine of Patent Document 1, an engine, an HST pump that is driven by power of the engine, a travel operation device that operates the HST pump, and a pressure control that controls a travel primary side pressure that is a primary pressure of the travel operation device. And a control device for controlling the pressure control valve.

  The control device controls the engine stall by controlling the pressure control valve based on a no-load characteristic line that is used when the load is unloaded and a drop characteristic line that is adopted when a load greater than a predetermined level is applied to the engine. It is preventing.

JP 2013-36274 A

  Now, when performing engine stall prevention, whether or not an engine stall occurs in advance is determined based on, for example, a drop amount that is a difference between the actual engine speed and the target engine speed. As the target engine speed, for example, an accelerator depression amount or the like is employed. However, in the calculation of the drop amount, when the state of the work machine changes, it may be difficult to adopt the accelerator depression amount that has been used conventionally as the target engine speed.

  The present invention has been made to solve the above-described problems of the prior art, and appropriately determines whether an engine stall may occur even when the state of the work machine changes. An object is to provide a working machine capable of performing the above.

The technical measures taken by the present invention to solve the technical problem are as follows.
An index value is determined based on a prime mover, a hydraulic pump that operates by power of the prime mover and discharges hydraulic oil, a detection unit that detects a state of the work implement, and a state of the work implement that is detected by the detection unit An index determination unit; a calculation unit that calculates a drop amount of the prime mover based on the index value determined by the index unit determination unit and the actual rotational speed of the prime mover; and the hydraulic pump when the drop amount is equal to or greater than a predetermined value An output reduction unit that reduces the output of the motor and a command member that commands a target rotational speed of the prime mover , wherein the detection unit is a measurement device that detects the temperature of the fluid flowing in the working machine, and the index determination unit Determines the rotational speed of the prime mover set corresponding to the fluid as the index value when the temperature of the fluid detected by the measuring device is equal to or lower than a predetermined value, and the temperature exceeds the predetermined value Before if The target revolution speed of the prime mover is commanded by a command member is determined as the index value.

The work machine includes a prime mover, a hydraulic pump that operates by the power of the prime mover and discharges hydraulic oil, a detection unit that detects a state of the work machine, and an index based on the state of the work machine detected by the detection unit An index determining unit that determines a value, an arithmetic unit that calculates a drop amount of the prime mover based on the index value determined by the index unit determining unit and the actual rotational speed of the prime mover, and the drop amount is greater than or equal to a predetermined amount And a command member for commanding a target rotational speed of the prime mover, and the index determination unit obtains an error of a device provided in the work machine. The rotational speed of the prime mover set corresponding to the error is determined as the index value, and the target rotational speed of the prime mover commanded by the command member when the error of the device is not acquired is used as the index value. Determined.

The working machine includes a command member that commands a target rotational speed of the prime mover, and the detection unit is a measuring device that can measure the temperature of either oil or cooling water that is a fluid flowing in the working machine, The index determination unit determines a preset number of revolutions of the prime mover as the index value when the temperature detected by the measurement device is equal to or higher than a predetermined value and the target rotational speed is equal to or higher than a predetermined value.
The work machine includes a command member that commands a target rotational speed of the prime mover, the detection unit is a first error detection unit that detects an error generated in the command member, and the index determination unit is the first determination unit When the error detection unit detects an error in the command member, a predetermined rotation speed of the prime mover is determined as the index value.

The work machine includes a control unit that sets the rotation number of the prime mover to a set rotation number that is a predetermined rotation number, and the detection unit is a second error detection unit that detects an error that has occurred in the control unit,
When the second error detection unit detects an error of the control unit, the index determination unit determines the rotation speed of the prime mover set according to the error as the index value.

  ADVANTAGE OF THE INVENTION According to this invention, even if the state of a working machine changes, it can be judged appropriately whether an engine stall may generate | occur | produce.

It is a figure which shows the hydraulic system (hydraulic circuit) of the traveling system of a working machine. It is a figure which shows the hydraulic system (hydraulic circuit) of the working system of a working machine. It is a figure which shows the relationship between an engine speed, driving | running | working primary pressure, and a control line. It is a figure which shows the flow of anti-stall control. It is a figure which shows the flow of the anti-stall control of a 1st modification. It is a figure which shows the relationship between temperature and an engine speed (2nd setting speed). It is a figure which shows the flow of the anti-stall control of a 2nd modification. It is a figure which shows the hydraulic system in a 3rd modification. It is a figure which shows the flow of the anti-stall control of a 3rd modification. It is a figure which shows the hydraulic system in a 4th modification. It is a figure which shows the flow of the anti-stall control of a 4th modification. It is a side view which shows the track loader which is an example of a working machine. It is a side view which shows a part of track loader of the state which raised the cabin.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a hydraulic system for a working machine and a working machine provided with the hydraulic system according to the invention will be described with reference to the drawings as appropriate.
First, the overall configuration of the work machine will be described.
As shown in FIGS. 12 and 13, the work machine 1 according to the present invention includes a machine frame 2, a work device 3 attached to the machine frame 2, and a traveling device 4 that supports the machine frame 2. . 12 and 13, a truck loader is shown as an example of a working machine. However, the working machine according to the present invention is not limited to a truck loader. For example, a tractor, a skid steer loader, a compact truck loader, a backhoe, etc. It may be. In the present invention, the front side (left side in FIG. 12) of the driver seated in the driver's seat of the work machine is front, the rear side (right side in FIG. 12) is rearward, and the left side of the driver (front side in FIG. 12). Side) is the left side, and the right side of the driver (the back side in FIG. 12) is the right side.

A cabin 5 is mounted on the upper part of the body frame 2 and in the front part. The rear portion of the cabin 5 is supported by the support bracket 11 of the body frame 2 so as to be swingable around the support shaft 12. The front part of the cabin 5 can be placed on the front part of the body frame 2.
A driver's seat 13 is provided in the cabin 5. A travel operation device 14 for operating the travel device 4 is disposed on one side (for example, the left side) of the driver seat 13.

The traveling device 4 is a crawler traveling device. The traveling device 4 is provided below the left side of the body frame 2 and below the right side of the body frame 2. The traveling device 4 includes a first traveling unit 21L and a second traveling unit 21R that operate by hydraulic drive, and can travel by the first traveling unit 21L and the second traveling unit 21R.
The work device 3 includes a pair of booms 22 including a boom 22 </ b> L and a boom 22 </ b> R, and a bucket 23 (work tool) attached to the tip of the boom 22. The boom 22L is disposed on the left side of the body frame 2. The boom 22R is disposed on the right side of the body frame 2. The boom 22L and the boom 22R are connected to each other by a connecting body. The boom 22L and the boom 22R are supported by the first lift link 24 and the second lift link 25. A lift cylinder 26 composed of a double-acting pressure cylinder is provided between the base side of the boom 22L and the boom 22R and the rear lower part of the body frame 2. By simultaneously expanding and contracting the lift cylinder 26, the boom 22L and the boom 22R swing up and down. A mounting bracket 27 is pivotally supported on the distal ends of the boom 22L and the boom 22R so as to be rotatable about the horizontal axis, and the back side of the bucket 23 is attached to the mounting brackets 27 provided on the left and right.

Further, a tilt cylinder 28 composed of a double-acting hydraulic cylinder is interposed between the mounting bracket 27 and the middle part of the boom 22L and the front end side of the boom 22R. The bucket 23 swings (squeeze / dump operation) by the expansion and contraction of the tilt cylinder 28.
The bucket 23 is detachable from the mounting bracket 27. By removing the bucket 23 and attaching various attachments (hydraulic drive work tools having a hydraulic actuator described later) to the mounting bracket 27, various work other than excavation (or other excavation work) can be performed. ing.

  A prime mover 29 is provided on the rear side on the bottom wall of the body frame 2, and a fuel tank and a hydraulic oil tank 31 are provided on the front side on the bottom wall of the body frame 2. The prime mover 29 is, for example, a diesel engine. The prime mover 29 may be an electric motor, or a diesel engine and an electric motor. A diesel engine is sometimes simply called an engine.

Next, a hydraulic system for a working machine according to the present invention will be described.
FIG. 1 shows an overall view of a traveling hydraulic system. FIG. 2 shows an overall view of a working hydraulic system.
First, a traveling hydraulic system will be described.
As shown in FIGS. 1 and 2, the hydraulic system (hydraulic circuit) includes a first hydraulic pump P1 and a second hydraulic pump P2. The first hydraulic pump P <b> 1 and the second hydraulic pump P <b> 2 are hydraulic pumps that are driven by the power of the prime mover 29 to discharge hydraulic oil, and are configured by, for example, constant capacity type gear pumps.

  The first hydraulic pump P <b> 1 (main pump) is used to drive a hydraulic actuator of an attachment attached to the lift cylinder 26, the tilt cylinder 28 or the tip side of the boom 22. The second hydraulic pump P2 (pilot pump, charge pump) is mainly used for supplying a control signal (pilot pressure). Hereinafter, for convenience of explanation, the hydraulic oil discharged from the second hydraulic pump P2 and the hydraulic fluid for the control signal may be referred to as pilot oil, and the pressure of the pilot oil may be referred to as pilot pressure.

  As shown in FIG. 1, a discharge oil passage 100a is connected to the second hydraulic pump P2. A first supply / discharge passage 100b and a second supply / discharge passage 100c are connected to the discharge oil passage 100a. A first drive circuit 32A and a second drive circuit 32B are connected to the first supply / discharge path 100b. A travel operation device 14 is connected to the second oil supply / discharge passage 100c. A proportional valve 45 is connected to the middle portion of the second supply / discharge oil passage 100c.

The first drive circuit 32A is a circuit that drives the first travel unit 21L provided on the left, and the second drive circuit 32B is a circuit that drives the second travel unit 21R provided on the right.
The first drive circuit 32A includes an HST pump (travel hydraulic pump) 66. The HST pump 66 is connected to the corresponding HST motors 57 of the first traveling portions 21L and 21R by a pair of speed change oil passages 100h and 100i. Note that the second drive circuit 32B has the same structure as the first drive circuit 32A, and a description thereof will be omitted.

The HST pump 66 is a swash plate type variable displacement axial pump driven by the power of the prime mover 29 and a pilot type hydraulic pump (swash plate type variable displacement hydraulic pump) in which the angle of the swash plate is changed by the pilot pressure. . Specifically, the HST pump 66 includes a forward pressure receiving portion 66a and a reverse pressure receiving portion 66b on which pilot pressure acts.
The angle of the swash plate is changed by the pilot pressure acting on the pressure receiving portions 66a and 66b. When the angle of the swash plate is changed, the discharge direction and the discharge amount of the hydraulic oil are changed, thereby changing the rotation outputs of the first traveling unit 21L and the second traveling unit 21R.

The first travel unit 21L includes a travel motor 57 (travel hydraulic motor), a swash plate switching cylinder 58, a brake mechanism 59, a flushing valve 60, and a flushing relief valve 61.
The traveling motor 57 is an HST motor, and is a hydraulic device that is operated by pilot oil (hydraulic oil). The traveling motor 57 is, for example, a swash plate type variable displacement axial motor that can shift to high and low speeds. The swash plate of the traveling motor 57 is provided with a telescopic swash plate switching cylinder 58. By the expansion and contraction of the swash plate switching cylinder 58, the angle of the swash plate of the traveling motor 57 can be changed. By changing the angle of the swash plate of the travel motor 57, the travel motor 57 is shifted to the first speed or the second speed.

  The first hydraulic pressure switching valve 63 is a two-position switching valve having a spool that can move between a first position 63a and a second position 63b in accordance with the pressure of the pilot oil (pilot pressure). When the pilot pressure reaches a predetermined pressure, the spool of the first hydraulic pressure switching valve 63 moves to the second position 63b, and the operating state changes. Further, the spool of the first hydraulic pressure switching valve 63 is returned to the first position 63a by the spring when the pilot pressure becomes less than a predetermined pressure, and the operating state is changed. When the spool of the first hydraulic pressure switching valve 63 is in the operating state moved to the first position 63a, the pilot oil is removed from the swash plate switching cylinder 58 and contracts, and the traveling motor 57 enters the first speed state. When the spool of the first hydraulic pressure switching valve 63 is in the operating state moved to the second position 63b, the pilot oil is supplied to the swash plate switching cylinder 58 and extends, and the traveling motor 57 enters the second speed state.

  The first hydraulic pressure switching valve 63 is switched by the second hydraulic pressure switching valve 62. The first hydraulic pressure switching valve 63 and the second hydraulic pressure switching valve 62 are connected by a third supply / discharge path 100d. The second hydraulic pressure switching valve 62 is a two-position switching valve having a spool that can move between a first position and a second position in accordance with the pressure of the pilot oil (pilot pressure). When the second hydraulic pressure switching valve 62 is in the first position, the first hydraulic pressure switching valve 63 is in the first position 63a. When the second hydraulic pressure switching valve 62 is in the second position, the first hydraulic pressure switching valve 63 is in the second position 63b. The switching of the second hydraulic pressure switching valve 62 can be performed by an electric signal, a pilot pressure, a machine operation, or the like. Therefore, the traveling motor 57 can be switched to the first speed or the second speed by switching the second hydraulic pressure switching valve 62 to the first position or the second position.

  The HST pump 66 and the travel motor 57 are operated by the travel operation device 14. The travel operation device 14 includes a plurality of remote control valves, a travel lever 40, and first to fourth shuttle valves 41, 42, 43, 44. The plurality of remote control valves include a remote control valve 36, a remote control valve 37, a remote control valve 38, and a remote control valve 39. The remote control valves 36, 37, 38 and 39 are operated in common, that is, by one traveling lever 40. The remote control valves 36, 37, 38, 39 change the pressure of the hydraulic oil according to the operation of the travel lever 40 (operation member).

  The travel lever 40 can tilt from the neutral position in the front-rear direction, the width direction orthogonal to the front-rear direction, and the oblique direction. By tilting the traveling lever 40, the remote control valves 36, 37, 38, 39 of the traveling operation device 14 are operated. Then, a pilot pressure proportional to the operation amount from the neutral position of the travel lever 40 is output from the secondary side ports of the remote control valves 36, 37, 38, 39.

  When the traveling lever 40 is tilted forward (in the direction of arrow A1 in FIG. 1), the remote control valve 36 is operated and pilot pressure is output from the remote control valve 36. The pilot pressure acts on the forward pressure receiving portion 66a of the first drive circuit 32A from the first shuttle valve 41 via the first flow path 46 and is second from the second shuttle valve 42 via the second flow path 47. It acts on the forward pressure receiver 66a of the drive circuit 32B. As a result, the output shafts 57a of the first traveling unit 21L and the second traveling unit 21R rotate forward (forward rotation) at a speed proportional to the tilting amount of the traveling lever 40, and the track loader 1 moves straight forward.

When the travel lever 40 is tilted rearward (in the direction of arrow A2 in FIG. 1), the remote control valve 37 is operated and pilot pressure is output from the remote control valve 37. The pilot pressure acts on the backward pressure receiving portion 66b from the third shuttle valve 43 via the third flow path 48 and the second drive pressure 32b from the fourth shuttle valve 44 via the fourth flow path 49. The drive circuit 32B acts on the reverse pressure receiving portion 66b. As a result, the output shafts 57a of the first traveling unit 21L and the second traveling unit 21R are reversely rotated (reversely rotated) at a speed proportional to the tilting amount of the traveling lever 40, and the track loader 1 moves straight backward.

  Further, when the traveling lever 40 is tilted to the right (in the direction of arrow A3 in FIG. 1), the remote control valve 38 is operated and pilot pressure is output from the remote control valve 38. This pilot pressure acts on the forward pressure receiving portion 66a of the first drive circuit 32A from the first shuttle valve 41 via the first flow path 46, and from the fourth shuttle valve 44 via the fourth flow path 49 to the second drive. The circuit 32B acts on the backward pressure receiving portion 66b. As a result, the output shaft 57a of the first traveling unit 21L rotates in the forward direction and the output shaft 57a of the second traveling unit 21R rotates in the reverse direction, so that the track loader 1 turns to the right.

  Further, when the traveling lever 40 is tilted to the left (in the direction of arrow A4 in FIG. 1), the remote control valve 39 is operated and pilot pressure is output from the remote control valve 39. This pilot pressure acts on the forward pressure receiving portion 66a of the second drive circuit 32B from the second shuttle valve 42 via the second flow path 47, and also from the third shuttle valve 43 via the third flow path 48 for the first drive. The circuit 32A acts on the reverse pressure receiving portion 66b. As a result, the output shaft 57a of the second traveling unit 21R rotates in the forward direction and the output shaft 57a of the first traveling unit 21L rotates in the reverse direction, so that the track loader 1 turns to the left.

Further, when the traveling lever 40 is tilted in the oblique direction, the first traveling portion 21L and the first traveling portion 21L and the differential pressure between the forward pressure receiving portion 66a and the reverse pressure receiving portion 66b of each of the first drive circuits 32A and 32B are caused. The rotation direction and rotation speed of the output shaft 57a of the second traveling unit 21R are determined, and the truck loader 1 turns right or left while moving forward or backward.
In other words, when the travel lever 40 is tilted to the left and forward, the track loader 1 turns left at a speed corresponding to the tilt angle of the travel lever 40, and when the travel lever 40 is tilted to the right and forward, the travel lever 40 is moved. When the track loader 1 turns right while moving forward at a speed corresponding to the tilt angle, and the travel lever 40 is tilted to the left rear side, the track loader 1 moves backward at a speed corresponding to the tilt angle of the travel lever 40. When turning left and tilting the traveling lever 40 to the right rear side, the truck loader 1 turns right while moving backward at a speed corresponding to the tilting angle of the traveling lever 40.

Next, a working hydraulic system will be described.
As shown in FIG. 2, a discharge oil passage 100e is connected to the first hydraulic pump P1. A plurality of control valves 70 are connected to the discharge oil passage 100e. The plurality of control valves 70 are a boom control valve 70A, a bucket control valve 70B, and a preliminary control valve 70C. The boom control valve 70A is a valve that controls the lift cylinder 26, the bucket control valve 70B is a valve that controls the tilt cylinder 28, and the preliminary control valve 70C is a valve that controls the hydraulic actuator of the preliminary attachment. is there. In the working hydraulic system, the lift cylinder 26, the tilt cylinder 28, the hydraulic actuator for the spare attachment, and the like are hydraulic devices.

  The boom 22 and the bucket 23 can be operated by an operation member 71 provided around the driver's seat 13. The operation member 71 is supported so as to be tiltable from the neutral position in the front-rear direction, the width direction orthogonal to the front-rear direction, and the oblique direction. By operating the operation member 71 to tilt, the remote control valves 72A, 72B, 72C, 72D provided at the lower part of the operation member 71 can be operated.

When the operation member 71 is tilted forward, the remote control valve 72A is operated and pilot pressure is output from the remote control valve 72A. The pilot pressure acts on the pressure receiving portion of the boom control valve 70A, and the boom 22 is lowered by supplying the hydraulic oil that has entered the boom control valve 70A to the rod side of the lift cylinder 26.
When the operation member 71 is tilted rearward, the remote control valve 72B is operated and pilot pressure is output from the remote control valve 72B. The pilot pressure acts on the pressure receiving portion of the boom control valve 70A, and the boom 22 is raised by supplying the hydraulic oil that has entered the boom control valve 70A to the bottom side of the lift cylinder 26.

That is, the boom control valve 70A is applied to the lift cylinder 26 in accordance with the hydraulic oil pressure (the pilot pressure set by the remote control valve 72A and the pilot pressure set by the remote control valve 72B) set by operating the operation member 71. The flow rate of the flowing hydraulic oil can be controlled.
When the operation member 71 is tilted to the right, the remote control valve 72C is operated, and the pilot oil acts on the pressure receiving portion of the bucket control valve 70B. As a result, the bucket control valve 70B operates in a direction in which the tilt cylinder 28 is extended, and the bucket 23 performs a dumping operation at a speed proportional to the tilting amount of the operation member 71.

When the operation member 71 is tilted to the left, the remote control valve 72D is operated, and the pilot oil acts on the pressure receiving portion of the bucket control valve 70B. As a result, the bucket control valve 70B operates in a direction to reduce the tilt cylinder 28, and the bucket 23 performs a squeeze operation at a speed proportional to the tilting amount of the operation member 71.
That is, the bucket control valve 70B is applied to the tilt cylinder 28 in accordance with the hydraulic oil pressure (the pilot pressure set by the remote control valve 72C, the pilot pressure set by the remote control valve 72D) set by operating the operation member 71. The flow rate of the flowing hydraulic oil can be controlled. That is, the remote control valves 72A, 72B, 72C, 72D change the pressure of the hydraulic oil according to the operation of the operation member 71 and supply the changed hydraulic oil to the boom control valve 70A and the bucket control valve 70B.

  The operation of the preliminary control valve 70C is performed by the first electromagnetic valve 73A and the second electromagnetic valve 73B. When the first electromagnetic valve 73A is opened, the pilot oil acts on one pressure receiving portion of the preliminary control valve 70C. When the second electromagnetic valve 73B is opened, pilot oil acts on the other pressure receiving portion of the preliminary control valve 70C. Therefore, when pilot oil acts on one pressure receiving portion or the other pressure receiving portion of the preliminary control valve 70C, the preliminary control valve 70C is switched, and the preliminary actuator of the preliminary attachment is operated by the hydraulic oil supplied from the preliminary control valve 70C. . The operation of the first electromagnetic valve 73A and the second electromagnetic valve 73B is performed by a second control unit 82 described later.

As shown in FIGS. 1 and 2, the track loader (work machine) 1 includes a control unit that performs control related to the work machine. The control unit includes a first control unit 81 and a second control unit 82. 1 and 2 show the second control unit 82, the second control unit 82 shown in FIG. 1 is the same as the second control unit 82 shown in FIG.
The first control unit 81 is a control device that controls the prime mover 29. When the prime mover 29 is an engine, the first control unit 81 is an engine control device. For convenience of explanation, it is assumed that the prime mover 29 is an engine.

  A command member 83 that commands a target engine speed (referred to as a target engine speed) is connected to the first controller 81. The command member 83 includes a pedal portion 83a and a sensor 83b that detects an operation amount of the pedal portion 83a. The pedal portion 83a is an accelerator lever supported in a swingable manner or an accelerator pedal supported in a swingable manner. The operation amount detected by the sensor 83 b is input to the first control unit 81. The operation amount detected by the sensor 83b is the target engine speed. The first control unit 81 is connected to a sensor 84 that detects an actual engine speed (referred to as an actual engine speed).

  The engine control of the first control unit 81 is general, and for example, a control signal indicating the fuel injection amount, the injection timing, and the fuel injection rate is output to the injector. The first control unit 81 outputs a signal indicating the fuel injection pressure and the like to the supply pump and the common rail. That is, the first control unit 81 controls the injector, the supply pump, and the common rail so that the actual engine speed becomes the target engine speed.

  The second control unit 82 is a control device that controls the hydraulic system. For example, the second control unit 82 controls the first electromagnetic valve 73A and the second electromagnetic valve 73B. A switch 74 provided around the driver's seat 13 is connected to the second control unit 82. The switch 74 is configured by, for example, a swingable seesaw type switch, a slide type switch that can slide, or a push type switch that can be pressed. The operation of the switch is input to the second control unit 82. By the operation of the switch 74, the first electromagnetic valve 73A or the second electromagnetic valve 73B is opened and closed. Therefore, the preliminary actuator can be operated under the control of the second control unit 82.

Now, the 2nd control part 82 performs control (anti-stall control) which prevents an engine stall. Specifically, the proportional valve 45 is connected to the second control unit 82. The second control unit 82 prevents engine stall by changing the opening of the proportional valve 45 based on the engine drop amount, which is the difference between the target engine speed and the actual engine speed. The second control unit 82 can acquire the actual engine speed and the target engine speed.

Hereinafter, the anti-stall control will be described in detail.
FIG. 3 shows the relationship between the engine speed, the traveling primary pressure, and the control lines L1 and L2.
The traveling primary pressure is the pressure (pilot pressure) of hydraulic oil in the oil passage from the proportional valve 45 to the remote control valve (remote control valves 36, 37, 38, 39) in the second supply / discharge oil passage 100c. That is, it is the primary pressure of the hydraulic oil that enters the remote control valve provided in the traveling lever 40 that performs the traveling operation. The control line L1 shows the relationship between the engine speed and the traveling primary pressure when the drop amount is less than a predetermined amount. The control line L2 shows the relationship between the engine speed and the traveling primary pressure when the drop amount is greater than or equal to a predetermined amount.

  When the drop amount is less than the predetermined value, the second control unit 82 adjusts the opening degree of the proportional valve 45 so that the relationship between the actual engine speed and the traveling primary pressure matches the control line L1. Further, the second control unit 82 adjusts the opening degree of the proportional valve 45 so that the relationship between the actual engine speed and the traveling primary pressure coincides with the control line L2 when the drop amount is equal to or larger than a predetermined amount. . In the control line L2, the traveling primary pressure for a predetermined engine speed is lower than the traveling primary pressure of the control line L1. That is, when attention is paid to the same engine speed, the traveling primary pressure of the control line L2 is lower than the traveling primary pressure of the control line L1. Therefore, the pressure (pilot pressure) of the hydraulic oil entering the remote control valve is kept low by the control based on the control line L2. As a result, the swash plate angle of the HST pump 66 of the HST pump (running hydraulic pump) 66 is adjusted, the load acting on the engine 29 is reduced, and the engine 29 can be prevented from stalling. In FIG. 3, one control line L2 is shown, but a plurality of control lines L2 may be provided. For example, the control line L2 may be set for each engine speed. Further, it is preferable that the second control unit 82 has data indicating the control lines L1 and L2, or control parameters such as functions.

  In the anti-stall control, control based on the state of the work machine is performed. The state of the work machine includes various devices, fluids, and the like provided in the work machine. The fluid state includes an engine oil temperature state, a hydraulic oil temperature state, a cooling water temperature state, and the like. In addition, the state of the device is the presence or absence of an error that is generated or detected by a sensor, a control device, an engine, or the like mounted on the work machine. The state of the work implement is detected by the detection unit 90.

First, anti-stall control based on oil temperature (oil temperature) will be described in detail as the state of the work implement.
In the work machine 1, the detection unit 90 is a measuring device that detects the temperature of oil. For example, the measuring device 90 measures the temperature of hydraulic fluid supplied to a hydraulic actuator (lift cylinder 26, tilt cylinder 28, spare actuator, etc.). Note that the measuring device 90 may be a device that measures the temperature of the engine oil instead of the temperature of the hydraulic oil. Hereinafter, for convenience of explanation, the hydraulic oil or the engine oil is referred to as “first oil temperature”. The first oil temperature can be input to the first control unit 81 and / or the second control unit 82.

  When the first oil temperature (hydraulic oil temperature) is equal to or lower than a predetermined value, the second control unit 82 fixes the target engine speed of the engine to a first set engine speed that is a predetermined engine speed. In other words, the second control unit 82 instructs the first control unit 81 that controls the engine speed to set the target engine speed to the first set speed. The first controller 81 sets the first set rotational speed commanded from the second controller 82 to the target rotational speed of the engine. The first set rotational speed is, for example, 1800 rpm. That is, when the first oil temperature (hydraulic oil temperature) is low, the second control unit 82 fixes the target engine speed of the engine to the first set engine speed (1800 rpm) to the hydraulic system (working apparatus). Protect the various devices provided. On the other hand, when the first oil temperature (the temperature of the hydraulic oil) is equal to or higher than a predetermined value, the second control unit 82 (when the first oil temperature rises and it is not necessary to protect various devices). Does not instruct the first controller 81 to set the target engine speed of the engine to the first set engine speed. Since there is no command from the first control unit 81, the second control unit 82 sets the engine speed commanded by the command member 83 to the target engine speed.

The second control unit 82 includes an index determination unit 82a, a calculation unit 82b, and an output reduction unit 82c. The index determination unit 82a, the calculation unit 82b, and the output reduction unit 82c are configured by a program, an electric / electronic circuit, an electric / electronic component, and the like incorporated in the second control unit 82.
The index determining unit 82a determines an index value (a value used when determining the engine drop amount) based on the first oil temperature (the temperature of the hydraulic oil). When the first oil temperature (hydraulic oil temperature) is low and the second control unit 82 sets the target engine speed of the engine to the first set speed, the index determination unit 82a uses the first set speed as the index value. To do. The calculation unit 82b calculates the engine drop amount based on the index value determined by the index unit determination unit 82a and the actual engine speed. That is, when the first oil temperature (hydraulic oil temperature) is low, the calculation unit 82b obtains the drop amount by “drop amount = first set rotation speed−actual engine rotation speed”. On the other hand, when the first oil temperature (hydraulic oil temperature) is high and the first control unit 81 sets the engine speed (accelerator value) commanded by the command member 83 to the target speed, the index determination unit 82a The accelerator value is used as an index value. When the first oil temperature is high, the calculation unit 82b obtains the drop amount by “drop amount = accelerator value−actual engine speed”.

The output reduction unit 82c reduces the output of the hydraulic pump (HST pump 66) when the drop amount is greater than or equal to a predetermined amount. As described above, when the drop amount is greater than or equal to the predetermined value, the output reduction unit 82c adjusts the opening of the proportional valve 45 so that the relationship between the actual engine speed and the traveling primary pressure matches the control line L2. adjust.
FIG. 4 shows a flow of setting of the engine speed and anti-stall control performed based on the temperature of the hydraulic oil (first oil temperature).

As shown in FIG. 4, after the engine is started, the second controller 82 determines whether or not the first oil temperature is low (S1). Note that the low temperature is a region where the viscosity of the oil becomes high and loads various devices, and is, for example, a state of zero degrees or less.
When the first oil temperature is low (S1, yes), the second control unit 82 fixes the target engine speed of the engine to the first set engine speed (S2). That is, it instructs the first control unit 81 to fix the target engine speed of the engine to the first set engine speed.

  On the other hand, when the first oil temperature is not low (S1, No), the second controller 82 does not instruct the first controller 82 to fix the target engine speed to the first set engine speed, The 1 control unit 81 sets the engine speed commanded by the command member 83 to the target speed (S3). When the target engine speed is the first set speed, the index determining unit 82a sets the first set speed as the index value (S4). On the other hand, when the target engine speed is not the first set engine speed, the index determination unit 82a sets the accelerator value as the index value (S5). When the index value is the first set rotation speed, the calculation unit 82b obtains the drop amount by “drop amount = first set rotation speed−actual engine rotation speed” (S6). When the index value is the accelerator value, the calculation unit 82b obtains the drop amount by “drop amount = accelerator value−actual engine speed” (S6). When the drop amount is greater than or equal to the predetermined amount, the output reduction unit 82c performs control based on the control line L2 (S7).

  As described above, when the oil temperature is low and the target rotation speed is fixed to the first set rotation speed, the second control unit 82 sets the index value for calculating the drop amount in the anti-stall control to the first set rotation speed. decide. When the oil temperature is low, the second control unit 82 determines whether or not the engine stall state is approaching by using the difference between the first set engine speed and the actual engine speed as a drop amount. However, anti-stall control can be performed appropriately. When the oil temperature is low and the difference between the accelerator value and the actual engine speed is used as the drop amount, the engine stall condition is approached due to the fact that the first set engine speed is fixed. Although it is not, it is judged that it is approaching the state of engine stall.

In the above-described embodiment, the first set rotational speed set by the second control unit 82 based on the first oil temperature (hydraulic oil temperature) is used as the index value, but instead, the first oil temperature (hydraulic oil) The target engine speed determined according to the temperature) may be used as an index value (Modification 1).
FIG. 5 shows an anti-stall control flow in the first modification. In the first modification, the description will be continued assuming that the oil temperature can be acquired by the second control unit 82. That is, the first oil temperature shown in FIG. 5 is the temperature of the hydraulic oil.

As shown in FIG. 5, the second control unit 82 acquires the oil temperature (first oil temperature) (S11).
When the first oil temperature is equal to or lower than the predetermined value (low temperature) (S12, Yes), the index determination unit 82a sets the engine speed (second set speed) set in accordance with the oil temperature as the index value. (S13). For example, as shown in FIG. 6, the second control unit 82 has a relationship between the first oil temperature and the engine speed (second set speed). The index determination unit 82a refers to the relationship between the first oil temperature and the engine speed (second set speed), and sets the engine speed (second set speed) corresponding to the first oil temperature as the index value. To do. The calculation unit 82b obtains the drop amount by “drop amount = second set rotational speed−actual engine rotational speed” (S13). When the drop amount is greater than or equal to the predetermined amount, the output reduction unit 82c performs control based on the control line L2 (S14).

Further, when the first oil temperature is high, the index value may be changed (Modification 2). FIG. 7 shows an anti-stall control flow in the second modification. In the second modification, the description will be continued assuming that the oil temperature can be acquired by the second control unit 82.
As shown in FIG. 7, the second controller 82 acquires the first oil temperature (S21). The index determining unit 82a determines whether or not the first oil temperature is equal to or higher than a predetermined value (high temperature) and is close to overheating (S22). The index determining unit 82a refers to the accelerator value and determines whether or not the accelerator value is 1800 rpm or more (whether or not it is the first threshold value or more) (S23). When the accelerator value is 1800 rpm or more, the index determining unit 82a determines 1800 rpm as the index value (S24). The computing unit 82b obtains the drop amount by “drop amount = first threshold−actual engine speed” (S25). On the other hand, when the first oil temperature is not equal to or higher than the predetermined value (high temperature) (S22, No), or the accelerator value is not equal to or higher than the first threshold (S23, No), the index determination unit 82a determines the accelerator value. Is set as an index value (S26). The calculation unit 82b obtains the drop amount by “drop amount = accelerator value−actual engine speed” (S27). When the drop amount is greater than or equal to the predetermined amount, the output reduction unit 82c performs control based on the control line L2 (S28).

  As described above, the index value may be determined based on the temperature of the hydraulic oil, but instead, the index value may be changed based on the temperature of the engine oil. When the index value is changed based on the temperature of the engine oil, the first control unit 81 performs setting of the target engine speed (setting of the first set speed or the second set speed). Moreover, the 1st control part 81 may have the parameter | index determination part 82a and the calculating part 82b instead of the 2nd control part 82. FIG.

Further, the index value may be changed when an error of a device provided in the work machine is acquired. Modification 3 in which the index value is changed based on the state of the command member 83 that is one of the devices will be described.
As shown in FIG. 8, the detection unit 91 is a part that detects the state of the command member 83, and is provided in the second control unit 82. The detection unit 91 includes a program, an electric / electronic circuit, an electric / electronic component, and the like provided in the second control unit 82. The detection unit 91 is a first error detection unit that detects an error that has occurred in the command member 83. The first error detection unit 91 detects, for example, a failure that has occurred in the pedal unit 83a as an error, or detects a failure that has occurred in the sensor 83b as an error. That is, the first error detecting unit 91 detects a case where the command value of the sensor 83b cannot be accurately read, a case where the sensor 83b indicates an abnormal value, and the like as a failure. The error detected by the first error detection unit 91 can be acquired by the first control unit 81.

FIG. 9 shows an anti-stall control flow in the third modification.
As shown in FIG. 9, the second control unit 82 monitors the state of the command member 83 in a state where the engine is operating (driven), and determines whether or not the sensor 83b has failed (S31). . When the first error detection unit 91 detects an error in which the sensor 83b has failed, that is, when an error indicating a failure in the sensor 83b has occurred (S31, yes), the index determination unit 82a performs engine idling. The rotational speed is determined as an index value (S32). The computing unit 82b obtains the drop amount by “drop amount = idling rotational speed−actual engine rotational speed” (SS33). On the other hand, when the first error detection unit 91 does not detect an error in which the sensor 83b is broken, that is, when an error indicating a failure in the sensor 83b does not occur (
(S31, No), the index determination unit 82a sets the accelerator value as the index value (S34). The calculation unit 82b obtains the drop amount by “drop amount = accelerator value−actual engine speed” (S35). When the drop amount is greater than or equal to the predetermined amount, the output reduction unit 82c performs control based on the control line L2 (S36).

  Moreover, you may change an index value based on the state of the 1st control part 81 which is one of the apparatuses mounted in the working machine (modification 4). As shown in FIG. 10, the detection unit 92 is a part that detects the state of the first control unit 81, and is provided in the first control unit 81. The detection unit 92 includes a program, an electric / electronic circuit, an electric / electronic component, and the like provided in the first control unit 81. The detection unit 92 is a second error detection unit that detects an error that has occurred in the first control unit 81. When the second error detection unit 92 detects an error in the first control unit 81, the index determination unit 82a determines the engine speed set according to the error as an index value.

FIG. 11 shows an anti-stall control flow in the fourth modification.
The first control unit 81 monitors its own state in a state where the engine is operating (driven), and determines whether or not an error is detected (S41). When the second error detection unit 92 detects an error, the first control unit 81 determines a level to be limited based on the content of the error (S42). In this embodiment, the error level is divided into three stages, and the error that can lead to equipment failure (engine failure, running device failure, working device failure) in the shortest period is the most. Although the level is a “high severity error” and it is difficult to directly connect to the failure of the equipment, the error that needs to be notified to the operator is the lowest level “minor error”, which is an error between a severe error and a minor error. Is a “medium error”.

  When the error is a serious error (S43, yes), the index determining unit 82a determines whether or not the accelerator value is equal to or higher than the idling speed (S44). When the accelerator value is equal to or higher than the idling speed (S44, yes), the index determining unit 82a determines the idling speed as the index value (S45). The computing unit 82b obtains the drop amount by “drop amount = idling speed−engine actual speed” (S46). On the other hand, even if it is a severe error, the index determination unit 82a sets the accelerator value as the index value when the accelerator value is less than the idling speed (S44, No) (S47). The calculation unit 82b obtains the drop amount by “drop amount = accelerator value−actual engine speed” (S48). When the drop amount is greater than or equal to the predetermined amount, the output reduction unit 82c performs control based on the control line L2 (S50).

  When the error is not a severe error (S43, No), the index determining unit 82a determines whether or not it is a moderate error (S51). In the case of a medium error, the index determining unit 82a determines whether or not the accelerator value is 1800 rpm or more (first threshold or more) (S52). When the accelerator value is equal to or greater than the first threshold value (S52, yes), the index determination unit 82a determines the first threshold value as the index value (S53). The calculation unit 82b obtains the drop amount by “drop amount = first threshold−actual engine speed” (S54). On the other hand, even if it is a moderate error, the index determination unit 82a sets the accelerator value as the index value when the accelerator value is less than the idling speed (S52, No) (S55). The calculation unit 82b obtains the drop amount by “drop amount = accelerator value−actual engine speed” (S56). When the drop amount is greater than or equal to the predetermined amount, the output reduction unit 82c performs control based on the control line L2 (S50).

  The index determination unit 82a determines whether the accelerator value is 2280 rpm or more (second threshold or more) when the error is not a medium error (No in S51) and is a minor error (S61). When the accelerator value is greater than or equal to the second threshold value (S61, yes), the index determination unit 82a determines the second threshold value as the index value (S62). The computing unit 82b obtains the drop amount by “drop amount = second threshold−actual engine speed” (S63). On the other hand, even if it is a minor error, the index determination unit 82a sets the accelerator value as the index value when the accelerator value is less than the second threshold (S61, No) (S64). The calculation unit 82b obtains the drop amount by “drop amount = accelerator value−actual engine speed” (S65). When the drop amount is greater than or equal to the predetermined amount, the output reduction unit 82c performs control based on the control line L2 (S50).

In the above-described embodiment, the index value is changed based on the error of the first control unit 81, but the error of the second control unit 82 may be used. Further, the first control unit 81 and the second control unit 82 are not limited to the failure of the control unit, and may be anything as long as these are detected work machine errors. For example, in the work machine, an error notifying the lack of urea or an error notifying the lack of fuel may be used. Therefore, even when various errors occur in the work machine, the anti-stall control can be accurately performed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. In the embodiment described above, the first operating valve 61 and the second operating valve 62 are two-position switching valves, but may be proportional valves instead. In the above-described embodiment, the traveling motor 51 and the brake mechanism 52 have been described as the hydraulic equipment. However, the hydraulic equipment may be anything as long as it operates with the pressure of hydraulic oil. The traveling motor is a motor that switches to the first speed or the second speed (the traveling state changes), but the number of switching stages of the traveling motor is not limited to the first speed and the second speed.

  In the above-described embodiment, the control (HST control) of the HST pump (travel hydraulic pump) 66 and the travel motor 57 is performed by hydraulic oil (pilot oil), but is not limited to this. For example, the control is electrically performed. You may go. That is, in HST control, swash plate control such as a traveling pump or traveling motor may be performed by an electromagnetic proportional valve or the like, or may be performed by other methods.

DESCRIPTION OF SYMBOLS 1 Working machine 29 Motor | power_engine 82 Control part 82a Index determination part 82b Calculation part 82c Output reduction part 90,91,92 Detection part

Claims (5)

Prime mover,
A hydraulic pump that operates by the power of the prime mover and discharges hydraulic oil;
A detection unit for detecting the state of the work implement;
An index determination unit that determines an index value based on the state of the work implement detected by the detection unit;
A calculation unit that calculates the drop amount of the prime mover based on the index value determined by the indicator part determination unit and the actual rotational speed of the prime mover;
An output reduction unit that reduces the output of the hydraulic pump when the drop amount is equal to or greater than a predetermined amount;
A command member for commanding a target rotational speed of the prime mover;
With
The detection unit is a measuring device that detects the temperature of the fluid flowing in the working machine,
The index determination unit determines a rotational speed of a prime mover set corresponding to the fluid as the index value when the temperature of the fluid detected by the measuring device is equal to or lower than a predetermined value, and the temperature is a predetermined value A working machine that determines the target rotational speed of the prime mover commanded by the command member as the index value when the command member is exceeded .   The index determination unit determines a preset number of revolutions of a prime mover as the index value when a temperature detected by the measuring device is equal to or higher than a predetermined value and the target rotational speed is equal to or higher than a predetermined value. The working machine according to 1. Prime mover,
A hydraulic pump that operates by the power of the prime mover and discharges hydraulic oil;
A detection unit for detecting the state of the work implement;
An index determination unit that determines an index value based on the state of the work implement detected by the detection unit;
A calculation unit that calculates the drop amount of the prime mover based on the index value determined by the indicator part determination unit and the actual rotational speed of the prime mover;
An output reduction unit that reduces the output of the hydraulic pump when the drop amount is equal to or greater than a predetermined amount;
A command member for commanding a target rotational speed of the prime mover;
With
The index determination unit determines the rotation speed of the prime mover set corresponding to the error as the index value when the error of the device provided in the work machine is acquired, and does not acquire the error of the device In this case, the working machine determines the target rotational speed of the prime mover commanded by the command member as the index value . The detection unit is a first error detection unit that detects an error that has occurred in the command member;
The work machine according to claim 3, wherein the index determination unit determines a predetermined rotation speed of the prime mover as the index value when the first error detection unit detects an error of a command member. A controller for setting the rotational speed of the prime mover to a set rotational speed that is a predetermined rotational speed;
The detection unit is a second error detection unit that detects an error that has occurred in the control unit,
5. The index determination unit according to claim 4, wherein when the second error detection unit detects an error of the control unit, the index determination unit determines a rotation speed of the prime mover set according to the error as the index value. Work machine.

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