JP2016138507A - Engine control device for work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine control device for a work vehicle, capable of suppressing engine noise and achieving low fuel consumption during composite operation of work and traveling while securing work efficiency and travel efficiency.SOLUTION: An engine control device 50 for controlling a work vehicle having a diesel engine 34, a travel device 1, and a work device 2 includes a controller 35 for setting a target engine speed of a diesel engine 34 on the basis of an operator's instruction, a pressure switch 37 as travel state detection means with which the work device 2 detects a travel state, and a pressure switch 30 as work state detection means with which the work device 2 detects a work state. The controller 35 executes isochronous control for making the engine speed of the diesel engine 34 constant when composite operation for jointly performing travel of the travel device 1 and work by the work device 2 is determined by the pressure switch 37 and the pressure switch 30.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an engine control device for a work vehicle.

  2. Description of the Related Art Conventionally, a traveling work machine including an engine control device that detects the traveling of a vehicle body and switches engine control (droop / isochronous control) is known (for example, see Patent Document 1).

  In Patent Document 1, a first engine control unit that sets a target rotational speed based on an instruction from an operator, and a second engine that controls a fuel injection amount based on the target rotational speed and controls the rotational speed of the engine. Control means and travel detection means for detecting the travel of the vehicle body, and the first engine control means determines whether the vehicle body is not traveling based on the detection result of the travel detection means, and the second engine control When the vehicle is not running, the engine is instructed so that the engine rotation characteristic becomes an isochronous characteristic, and when the vehicle is running, the engine rotation characteristic is instructed to become a droop characteristic, and the fuel injection amount control characteristic is switched. In this way, the engine rotational speed corresponding to the traveling state and working state of the work machine is being realized.

Japanese Patent No. 4437771

  However, in the technique described in Patent Document 1, when traveling operation is required during excavation / turning or the like, engine control becomes droop control. It is conceivable that the operability is lowered due to changes in speed and traveling speed. further. Since the droop control is performed at the time of such a combined operation of work and traveling, the engine speed increases at a light load, the engine noise increases, and the fuel consumption deteriorates.

  In order to take measures against the above problems (for example, to reduce shock of the vehicle body due to fluctuations in engine speed), the technique described in Patent Document 1 switches droop control / isochronous control during combined operation of work and travel. Is gradually changing. However, in this case, various sensors, a controller for controlling the various sensors, and the like are required as means for instructing the composite degree of the combined operation of work and travel, leading to an increase in cost.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an engine control device for a work vehicle that suppresses engine noise and achieves low fuel consumption during combined operation of work and travel while ensuring work performance and travel performance.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

That is, the invention according to claim 1
Engine,
A traveling device that travels by receiving the power of the engine;
An engine control device for controlling a work vehicle comprising: a work device driven by receiving power from the engine;
A controller for setting a target engine speed based on an instruction from an operator;
A traveling state detecting means for detecting a traveling state by the working device;
A working state detecting means for detecting the working state of the working device;
The controller is
Isochronous control for making the engine speed constant when it is determined by the running state detecting means and the working state detecting means that the running of the running device and the work by the working device are combined. To do.

  According to a second aspect of the present invention, in the engine control device for a work vehicle according to the first aspect of the present invention, means for detecting the load of the engine and, when there is no load, a means for setting the minimum unloaded speed of the engine. It is supposed to be prepared.

  As effects of the present invention, the following effects can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, while ensuring work performance and driving | running | working performance, it can suppress an engine noise and implement | achieve low fuel consumption at the time of the composite operation | work of work and driving | running | working.

The figure which shows the whole structure of the turning working vehicle by which the engine control apparatus which concerns on one Embodiment of this invention is mounted. The performance curve figure of a diesel engine. The figure which shows the structure of an engine control apparatus. The figure which shows the control flow of an engine control apparatus. The performance curve figure which shows the control aspect in the case of performing isochronous control and droop control which concern on this embodiment. (A) Performance curve diagram showing control mode when isochronous control is performed in working state, (b) Performance curve diagram showing control mode when droop control is performed in running state. The performance curve figure which shows the control aspect in the case of performing isochronous control in the combined operation state of work and traveling. Schematic of iso-fuel consumption line at the time of droop control.

  First, the overall configuration of a turning work vehicle 100 that is a work vehicle equipped with an engine control device 50 according to an embodiment of the present invention will be described with reference to FIG. However, the engine control device 50 can be mounted not only on the turning work vehicle 100 but also on an agricultural work vehicle or other work vehicles.

  As shown in FIG. 1, the turning work vehicle 100 mainly includes a traveling device 1, a working device 2, and a turning device 3 included in the working device 2.

  The traveling device 1 is driven by the power of the diesel engine 34 and causes the turning work vehicle 100 to travel. The traveling device 1 includes a pair of left and right crawlers 11 and 11, hydraulic motors 12 and 12, and the like. The hydraulic motors 12 and 12 drive the left and right crawlers 11 and 11 so that the turning work vehicle 100 can move forward and backward. It is said. Further, the turning work vehicle 100 can be turned by the hydraulic motors 12 and 12 independently driving the left and right crawlers 11 and 11.

  The work device 2 is driven by the power of the diesel engine 34 to perform excavation work such as earth and sand. The work device 2 includes a boom 21, an arm 22, a bucket 23, and the like, and enables excavation work by driving them independently.

  More specifically, the boom 21 is pivoted by a boom cylinder 21a that has one end supported by the front portion of the turning device 3 and is movable in a telescopic manner. Further, one end of the arm 22 is supported by the other end of the boom 21 and is rotated by an arm cylinder 22a that is movable in a telescopic manner. The bucket 23 is rotated by a bucket cylinder 23a that is supported at one end by the other end of the arm 22 and is movable in a telescopic manner. That is, the work device 2 forms an articulated structure that excavates earth and sand using the bucket 23.

  In addition, although this turning work vehicle 100 is set as the specification which attaches the bucket 23 and performs excavation work, for example, the specification which attaches a hydraulic breaker and performs crushing work may be sufficient, and it is not limited to this.

  In addition, the work device 2 includes a turning device 3. The turning device 3 turns the work device 2. The turning device 3 includes a turning table 31 and a hydraulic motor 32 for turning the turning table 31. The hydraulic motor 32 drives the turning table 31 to turn the work device 2. The turning device 3 is also provided with a control unit 33, a diesel engine 34, and an engine control device 50 that controls the diesel engine 34. The work device 2 and the turning device 3 are driven by pressure oil from a hydraulic pump driven by the diesel engine 34.

Further, a boom cylinder 21a for driving the boom 21, an arm cylinder 22a for driving the arm 22, a bucket cylinder 23a for driving the bucket 23, and a hydraulic motor 32 for turning the swivel base 31 are used for excavation and turning hydraulics related to excavation and turning. Actuator. The hydraulic oil for excavation / turning is operated by operating a working (excavation / turning) operation tool 332b, so that pressure oil flows in, and the working device 2 and the turning device 3 operate to perform excavation / turning work. .
The work state in the present embodiment includes a turning operation by the turning device 3 in addition to the work by the working device 2.

Specifically, the control unit 33 includes a control seat 331, an operation tool 332 (travel operation tool 332a, work operation tool 332b), a control panel, and the like. The diesel engine 34 is controlled by operating the operating tool 332, the control panel, etc. Further, the operator controls the hydraulic motors 12 and 32 by operating the operation tool 332 and the like. Further, the operator sets the engine speed N of the diesel engine 34 by operating an accelerator dial 36 (see FIG. 3) arranged on the control panel. At this time, as will be described in detail later, the target engine speed indicated by the accelerator dial 36 (also simply referred to as the accelerator instruction speed) is instructed to the controller 35 as the target engine speed of the diesel engine 34. Thus, the operator controls the turning work vehicle 100. The hydraulic motor 12 that drives the crawler 11 is provided with a pressure switch 37 as first traveling state detection means. The pressure switch 37 is disposed in the traveling motor drive oil passage of the hydraulic circuit in the hydraulic motor 12 and can detect that the traveling operation has been performed by the operator.
The configuration of the traveling state detection unit and the arrangement position of the traveling state detection unit are not limited, and rotation of the axle may be detected by a rotation sensor.

  The accelerator dial 36 and the diesel engine 34 are electrically connected via a controller 35. The controller 35 creates a control signal based on the electrical signal from the accelerator dial 36 and outputs the created control signal. Output to the diesel engine 34. That is, the controller 35 is a device that controls the output of the diesel engine 34. That is, the controller 35 controls the engine speed N of the diesel engine 34 based on the operation of the accelerator dial 36 by the operator.

In order to drive the excavation / swivel hydraulic actuator described above, a pressure switch 30 is disposed as a work state detection means in the hydraulic path. The pressure switch 30 can detect whether or not a work operation by the work device 2 or the turning device 3 is performed by an operator.
In the present embodiment, the configuration using the pressure switch 30 as a working state detection unit that detects whether or not the turning work vehicle 100 is in a working state will be specifically described, but is not particularly limited. For example, instead of the pressure switch 30, work state detection means such as a displacement sensor that detects whether or not the operation position of the operation tool 332b for operating the work device 2 or the turning device 3 is in the work state may be used. Further, the configuration of the work state detection unit and the arrangement position of the work state detection unit are not limited.

  The operation tool 332 and the diesel engine 34 are electrically connected via a controller 35. The controller 35 creates a control signal based on the electrical signal from the operation tool 332, and outputs the created control signal. Output to the diesel engine 34. That is, the controller 35 is a device that controls the output of the diesel engine 34. That is, the controller 35 controls the engine speed N of the diesel engine 34 based on the operation of the operation tool 332 by the operator.

  Although the above is the whole structure of the turning work vehicle 100, the control aspect of the diesel engine 34 is demonstrated below.

  First, the performance curve diagram showing the relationship between the engine speed N of the diesel engine 34 and the engine torque T will be described with reference to FIG.

  As shown in FIG. 2, the engine speed N of the diesel engine 34 can be arbitrarily changed from a low idle engine speed Nmin to a high idle engine speed Nmax. The diesel engine 34 can be freely operated within a range surrounded by a torque curve Tcurve formed by connecting the maximum torque points set for each engine speed N.

  The engine torque T of the diesel engine 34 becomes maximum at the maximum torque point at the engine speed Nm (maximum torque point Tm). In other words, in the diesel engine 34, the torque curve Tcurve is formed so as to have the maximum engine torque Tmax at the maximum torque point Tm at the engine speed Nm.

  Further, the engine output as a function of the engine speed N and the engine torque T of the diesel engine 34 becomes maximum at the maximum torque point (engine torque Te) at the engine speed Ne. In other words, in the diesel engine 34, the torque curve Tcurve is formed so that the maximum engine output is obtained at the maximum torque point (engine torque Te) at the engine speed Ne.

  Further, the engine speed N of the diesel engine 34 becomes the high idle engine speed Nmax at the maximum engine speed Nh when the diesel engine 34 is not loaded. In other words, the torque curve Tcurve is formed in the diesel engine 34 so that the maximum engine speed Nh when the diesel engine 34 is not loaded becomes the high idle engine speed Nmax.

  Next, the control mode when the droop control is performed and the control mode when the isochronous control is performed will be described with reference to FIG.

  The isochronous control is a control pattern in which the engine speed N is constant regardless of the increase or decrease of the load applied to the diesel engine 34. Here, assuming that the diesel engine 34 is operating at the engine torque Tx at the engine speed Nx (see the X1 point in the figure), the engine control device 50 is instructed when the load on the diesel engine 34 increases. The engine torque T is increased while maintaining the engine speed Nx of the diesel engine 34 constant (see point Xa2 in the figure).

  Further, when the load applied to the diesel engine 34 is reduced, the engine control device 50 reduces the engine torque T while keeping the engine speed Nx of the diesel engine 34 constant (see point Xa3 in the figure).

  As described above, in the isochronous control, the engine speed N can be made constant regardless of the increase or decrease of the load applied to the diesel engine 34, and therefore, the power of the diesel engine 34 can be stably transmitted to the traveling device 1 or the like. Is possible.

  On the other hand, the droop control is a control pattern in which the engine speed N is changed in accordance with an increase or decrease in the load applied to the diesel engine 34. Here, assuming that the diesel engine 34 is operating at the engine torque Tx at the engine rotational speed Nx (see the point X1 in the figure), the controller 35 is configured such that when the load on the diesel engine 34 increases, The engine torque T is increased while gradually decreasing the engine speed N of 34 (see point Xd2 in the figure).

  Further, when the load applied to the diesel engine 34 is reduced, the controller 35 decreases the engine torque T while gradually increasing the engine speed N of the diesel engine 34 (see point Xd3 in the figure).

  Thus, in the droop control, the engine speed N changes according to the increase or decrease of the load applied to the diesel engine 34.

  The above is the control mode when the droop control and the isochronous control are performed as the control pattern of the diesel engine 34. Next, referring to FIG. 3, the engine control device 50 for controlling the engine speed N of the diesel engine 34. The configuration of will be described.

  As shown in FIG. 3, the engine control device 50 includes a controller 35, an accelerator dial 36, a pressure switch 37 that is a travel state detection unit, a pressure switch 30 that is a work state detection unit, and an engine rotation of the diesel engine 34. It is mainly composed of a switching relay 38 which is a switching means for controlling the number N. A battery 39 that is a DC power supply is connected to the controller 35, and power is supplied from the battery 39 to the controller 35, the switching relay 38, and the like via the fuse 40.

  The controller 35 sets a target rotational speed (target engine rotational speed) of the diesel engine 34 based on an instruction from the operator. The controller 35 is for performing control of the engine speed N of the diesel engine 34 and other various controls, and mainly includes a central processing unit (CPU) 26, storage means (RAM, ROM) 27, selection means 28, and the like. Consists of. The controller 35 is electrically connected to an accelerator dial 36, a pressure switch 37 that is a traveling state detection means, a pressure switch 30 that is a work state detection means, a switching relay 38, and the like. The controller 35 creates a control signal based on electric signals input from the accelerator dial 36, the pressure switch 30, the pressure switch 37, and the like. The switching relay 38 is electrically connected to an actuator 34 a that is an engine speed control unit of the diesel engine 34. The actuator 34a is an actuator that is turned on and off by the switching relay 38, and the engine speed N is controlled by changing the fuel injection amount and the injection timing of the diesel engine 34 by the actuator. In this way, the controller 35 outputs the created control signal to the diesel engine 34.

  The storage means (RAM, ROM) 27 stores a plurality of control patterns in isochronous control and control patterns in droop control in order to control the diesel engine 34 in response to an operator request. And the selection means 28 which the controller 35 has selects the optimal control pattern according to work content, a driving | running state, etc. from these control patterns, creates a control signal based on the selected control pattern, and generates a diesel engine 34. The controller 35 controls the engine speed N of the diesel engine 34 in accordance with a control flow to be described later, and at a predetermined engine speed N, the diesel engine is based on a control pattern for isochronous control or a control pattern for droop control. 34 is controlled. By doing so, the controller 35 realizes the operation of the diesel engine 34 requested by the operator.

  The accelerator dial 36 is an instruction device that instructs the controller 35 about the target engine speed of the diesel engine 34. The accelerator dial 36 is a dial type (rotary type) switch that allows the operator to set the target engine speed by manually turning the dial, and for operating and adjusting the target engine speed of the diesel engine 34. That is, the accelerator dial 36 is for setting the target value (maximum output magnitude) of the engine speed N of the diesel engine 34 to a magnitude according to the work content and the like. The dial position (predetermined angle position) set by the accelerator dial 36 is output to the controller 35 as an electrical signal. When the operator operates the accelerator dial 36 to achieve a desired engine speed N, the controller 35 sets the engine speed N so that the controller 35 can provide an output corresponding to the traveling state and working state of the turning work vehicle 100. Is done. For example, when the accelerator dial 36 is operated by the operator, the operation content (target engine speed set by the operator) is instructed to the controller 35, and the controller 35 performs control based on the control flow according to the control flow described later. A signal is transmitted to the diesel engine 34, and the output of the diesel engine 34 is controlled.

  The accelerator dial 36 is arranged on a control panel provided in the control unit 33 so that an operator can operate the seat while sitting on the control seat 331.

The pressure switch 37 serving as a traveling state detection unit is disposed in the hydraulic motor 12 of the traveling device 1 and detects the traveling state of the traveling device 1. In the present embodiment, the pressure switch 37 detects the traveling state of the traveling device 1 by grasping the driving state of the hydraulic motor 12.
The travel state detection means is a position sensor that is configured by a rotary potentiometer or the like instead of the pressure switch 37 and detects the drive state of the travel device 1 by grasping the operation position of the travel operation tool 332a. The present invention is not particularly limited to this embodiment.

  The pressure switch 30 serving as a work state detecting means is disposed in a predetermined hydraulic path for driving the excavation / turning hydraulic actuator described above, and detects the work state of the work device 2. The pressure switch 30 detects whether the working device 2 is in the working state by grasping the driving state of the excavating / turning hydraulic actuator. The controller 35 determines whether or not the turning work vehicle 100 is in the working state by the pressure switch 30 that is the working state detecting means.

  The switching relay 38 is electrically connected to an actuator 34 a that is an engine speed control unit of the diesel engine 34. The switching relay 38 is used to control the maximum engine speed N in accordance with a control signal output from the controller 35. The controller 35 drives the actuator 34a of the diesel engine 34 by the switching relay 38 to control the fuel injection amount and the injection timing of the diesel engine 34, and the engine rotation according to the working state and traveling state of the turning work vehicle 100. The maximum number of revolutions of the number N is controlled.

  The above is the configuration of the engine control device 50 that controls the diesel engine 34. Next, the control flow of the engine control device 50 will be described with reference to FIG. FIG. 5 is a performance curve diagram showing a control mode when performing isochronous control and droop control according to the present embodiment. FIG. 6A is a performance curve diagram showing a control mode when isochronous control is performed in a working state. FIG. 6B is a performance curve diagram showing a control mode when the droop control is performed in the traveling state. FIG. 7 is a performance curve diagram showing a control mode when isochronous control is performed in the combined operation state (work + running).

First, in step S101, the controller 35 determines in what state the accelerator dial 36 that instructs the controller 35 to indicate the target engine speed. That is, the controller 35 grasps the target engine speed indicated by the accelerator dial 36, and the target engine speed exceeds the predetermined low idle engine speed or is equal to or lower than the predetermined low idle engine speed. Make a decision.
The means for instructing the target engine speed to the controller 35 is not limited to the accelerator dial 36. Further, step S101 is not an essential step in the control flow of the engine control device 50 shown in FIG.

  If the controller 35 determines that the target engine speed indicated by the accelerator dial 36 (also simply referred to as the accelerator instruction speed) exceeds a predetermined low idle engine speed, the controller 35 proceeds to step S102. If it is determined that the target engine speed is equal to or lower than the predetermined low idle engine speed, the process proceeds to step S103.

  In step S103, the controller 35 uses the selection means 28 to select a predetermined control pattern for isochronous control, and controls the diesel engine 34 based on the predetermined control pattern. Specifically, in step S103, the controller 35 selects a predetermined control pattern for isochronous control from the control patterns stored in the controller 35, and creates a control signal based on the selected control pattern. Then, the controller 35 outputs the created control signal to the diesel engine 34. In this case, because of the isochronous control, the engine speed N does not increase, and there is an advantage in terms of noise and fuel consumption compared to the droop control even at light loads.

  In step S102, the controller 35 operates the operational state of the turning work vehicle (this machine) 100 by the pressure switch 30 as the work state detection means and the pressure switch 37 as the travel state detection means (the travel device 1 and the work device 2 are operated). It is determined whether at least one of them is in operation) or on standby (for example, the diesel engine 34 is driven but the traveling device 1 and the work device 2 are stopped).

  If the controller 35 determines that the turning work vehicle 100 is in operation, the controller 35 proceeds to step S104. If the controller 35 determines that the turning work vehicle 100 is on standby, the controller 35 proceeds to step S105.

  In step S105, the controller 35 selects a predetermined control pattern in the droop control by the selection unit 28, and controls the diesel engine 34 based on the predetermined control pattern. Specifically, in step S105, the controller 35 selects a predetermined control pattern for droop control from the control patterns stored in the controller 35, and creates a control signal based on the selected control pattern. Then, the controller 35 outputs the created control signal to the diesel engine 34.

  In step S104, the controller 35 determines whether the operation state of the turning work vehicle (this machine) 100 is in operation (including the combined operation state in which the working device 2 is in the traveling state and the traveling device 1 is in the traveling state) or only traveling. Determine whether. Specifically, the controller 35 determines whether the turning work vehicle 100 is in a combined operation state and a traveling state by the pressure switch 30 as the working state detecting unit and the pressure switch 37 as the traveling state detecting unit. Make a decision.

  When the controller 35 determines that the turning work vehicle 100 is working (including the combined operation), the controller 35 proceeds to step S107, and determines that the turning work vehicle 100 is not in a working state but in a traveling state. If so, the process proceeds to step S106.

  In step S106, the controller 35 selects the control pattern P2 in the droop control shown in FIG. 6B by the selection means 28, and controls the diesel engine 34 based on the control pattern P2. Specifically, in step S106, the controller 35 selects a droop control pattern P2 from the control patterns stored in the controller 35, and creates a control signal based on the selected control pattern P2. Then, the controller 35 outputs the created control signal to the diesel engine 34. In the state where the traveling device 1 is only traveling in the turning work vehicle 100, it is important to ensure the vehicle speed and to know the climbing / downhill conditions, and therefore droop control in which the engine speed N changes is effective.

  In step S107, the controller 35 selects the control pattern P3 for isochronous control shown in FIG. 7 by the selection means 28, and controls the diesel engine 34 based on the control pattern P3. Specifically, in step S107, the controller 35 selects a control pattern P3 for isochronous control from the control patterns stored in the controller 35, and creates a control signal based on the selected control pattern P3. Then, the controller 35 outputs the created control signal to the diesel engine 34. That is, the controller 35 determines that the traveling of the traveling device 1 and the operation of the working device 2 are combined by the pressure switch 30 serving as the working state detecting unit and the pressure switch 37 serving as the traveling state detecting unit. In this case, isochronous control is performed to keep the rotational speed of the diesel engine 34 constant. In the case of a combined operation state of work and traveling, delicate work may be required, and the engine speed N does not fluctuate depending on the work load, and isochronous control in which the excavation / turning operation speed and travel speed do not change is effective. . In the case of a working state that does not involve a traveling state, the controller 35 selects a control pattern P1 for isochronous control from the control patterns stored in the controller 35, and a control signal based on the selected control pattern P1. The control pattern P1 is in the same control mode as the control pattern P3. By performing isochronous control at the time of the combined operation of operation and traveling or during operation, the engine speed N does not increase and low noise and low fuel consumption operation can be performed. Also, by performing isochronous control even during light load and combined operation, there is an advantage in terms of noise and fuel consumption compared to droop control.

  As described above, in this embodiment, the control pattern P1 of isochronous control applied in the working state shown in FIG. 6A and the control of droop control applied in the traveling state shown in FIG. 6B. The pattern P2 and the control pattern P3 of isochronous control to be applied in the combined operation state of work and travel shown in FIG. 7 are stored in advance in the storage means 27 of the controller 35. Select or instruct one.

The control pattern P1 for isochronous control shown in FIG. 6A is a control pattern used when the working device 2 of the turning work vehicle 100 is in operation (including when the turning device 3 is turned). In the case of the control pattern P1 of the isochronous control, the diesel engine 34 connects an isochronous line (a line where the engine speed N is constant even if the torque changes) and a maximum torque point set for each engine speed N. It is possible to operate freely within the range surrounded by the torque curve Tcurve. For example, in the case of this control pattern P1, there are four isochronous lines a1 to a4 indicated by dotted lines in FIG. 6A, and these isochronous lines a1 to a4 have an engine speed N from a high speed to a low speed. The case of four stages is shown, and the controller 35 can be appropriately changed according to the situation at the time of work.
In the present embodiment and FIG. 6A, four isochronous lines a1 to a4 are illustrated and described as a plurality of isochronous lines, but are not particularly limited. For example, the control pattern has a plurality of isochronous lines intermittently or continuously, and the plurality of isochronous lines are configured so that the engine speed N can be appropriately changed from a high speed to a low speed. You can also.
Further, the isochronous line a1 in FIG. 4 is the same as the isochronous line a1 in FIG.

Further, the droop control control pattern P2 shown in FIG. 6B is a control pattern used when the traveling device 1 of the turning work vehicle 100 is traveling. In the case of the control pattern P2 of the droop control, the diesel engine 34 has a droop line (a line inclined to the right where the engine speed N also changes when the torque changes) and the maximum torque set for each engine speed N. It is possible to operate freely within a range surrounded by a torque curve Tcurve formed by connecting points. For example, in the case of this control pattern P2, it has five droop lines b1 to b5 shown in FIG. 6B, and these droop lines b1 to b5 have five stages in which the engine speed N is high to low. In this case, the controller 35 can be changed as appropriate according to the situation during travel.
In addition, in this embodiment and FIG.6 (b), although five droop lines b1-b5 are illustrated and demonstrated as a some droop line, it does not specifically limit. For example, the control pattern has a plurality of droop lines intermittently or continuously, and the plurality of droop lines is configured so that the engine speed N can be appropriately changed from a high speed to a low speed in multiple stages. You can also.
Further, the droop line b1 in FIG. 4 is the same as the droop line b1 in FIG. 6B, and is given the same reference numerals.

The control pattern P3 for isochronous control shown in FIG. 7 is a control pattern used when the work device 2 of the turning work vehicle 100 is in the combined operation (work + running state). In the case of this control pattern P3 of isochronous control, the diesel engine 34 connects an isochronous line (a line where the engine speed N is constant even if the torque changes) and a maximum torque point set for each engine speed N. It is possible to operate freely within the range surrounded by the torque curve Tcurve. For example, in the case of the control pattern P3, there are four isochronous lines c1 to c4 indicated by dotted lines in FIG. In this case, the controller 35 can be changed as appropriate according to the situation during the combined operation.
In the present embodiment and FIG. 7, four isochronous lines c1 to c4 are illustrated and described as a plurality of isochronous lines, but are not particularly limited. For example, the control pattern has a plurality of isochronous lines intermittently or continuously, and the plurality of isochronous lines are configured so that the engine speed N can be appropriately changed from a high speed to a low speed. You can also.
Further, the isochronous line c1 in FIG. 4 is the same as the isochronous line c1 in FIG.

  In the control flow described above, droop control is performed when not working (step S106) and when not traveling (step S105), so there are problems in terms of noise and fuel consumption compared to isochronous control. When the load is detected and there is no load, the engine control device 50 is further equipped with a means for achieving a no-load minimum speed of the diesel engine 34, that is, a so-called auto-decel function, to solve the problem. Is possible. The auto-decel function is a function of so-called automatic low-speed control, which is intended to reduce fuel consumption and noise by automatically lowering the engine speed to a low idle speed under predetermined conditions in a working machine such as a hydraulic excavator. That is. For example, the auto-decel function is a function for reducing the engine speed N to a low idle speed when the operating tool 332b for operating the work device 2 is not operated for a predetermined time (when not working).

FIG. 8 is a schematic diagram of iso-fuel consumption lines during droop control. The schematic diagram of the iso-fuel consumption line is a graph showing the relationship between the engine output torque (N · m) on the vertical axis and the engine speed (min ⁻¹ ) on the horizontal axis. A curve indicated by a solid line in FIG. 8 is a curve (equal fuel consumption curve) connecting points having the same fuel consumption rate. In an internal combustion engine including a diesel engine, in general, the portion having an elliptical shape in the center of the graph has better fuel efficiency, and the fuel efficiency becomes worse as the distance from the elliptical portion is increased. In the droop control control pattern (engine output torque characteristic) indicated by the solid line in FIG. 8, if the engine speed characteristic decreases from the rated torque point T1 on the droop line b1, the fuel efficiency deteriorates. Is shown.

  In the engine control apparatus 50 configured as described above, (1) the diesel engine 34 is driven, but when the work and running are stopped, the droop control is applied, and the droop control and the auto-decel function described above are applied. In combination, fuel consumption and noise can be suppressed. In addition, (2) when the vehicle is traveling, droop control is applied, and traveling performance is improved. In addition, (3) when only during work, isochronous control is applied, workability is good, and fuel consumption and noise are suppressed. (4) In the combined operation of work and travel, isochronous control is applied, the workability is good, and fuel consumption and noise are suppressed. On the other hand, in the prior art (Patent Document 1), droop control is applied in the case of a combined operation of work and traveling, so workability, fuel consumption, and noise are inferior compared to the case of (4) above. .

  Specifically, in the case of the above (2), that is, in the case of only traveling, it is important to secure the vehicle speed and to understand the climbing / downhill situation, so the droop control is effective. On the other hand, in the case of the above (4), that is, in the case of a combined operation of work and traveling, a delicate work may be required, and the engine speed N does not fluctuate depending on the work load. Isochronous control that does not change becomes effective. In addition, by using isochronous control during combined operation, there is an advantage in terms of noise and fuel consumption compared to droop control even during light load and combined operation. In the case of (1), that is, droop control when not working and not running, there are problems in terms of noise and fuel consumption compared to isochronous control, but the problem is solved by installing an auto-decel function. Is possible.

  As described above, according to the present invention, it is possible to suppress engine noise and achieve low fuel consumption during combined operation and travel while ensuring work performance and travel performance.

1 traveling device 2 working device 34 diesel engine 35 controller 36 accelerator dial 30 pressure switch (working state detecting means)
37 Pressure switch (traveling state detection means)
50 Engine control device 100 Turning work vehicle

Claims (2)

Engine,
A traveling device that travels by receiving the power of the engine;
An engine control device for controlling a work vehicle comprising: a work device driven by receiving power from the engine;
A controller for setting a target engine speed based on an instruction from an operator;
A traveling state detecting means for detecting a traveling state by the working device;
A working state detecting means for detecting the working state of the working device;
The controller is
Isochronous control for making the engine speed constant when it is determined by the running state detecting means and the working state detecting means that the running of the running device and the work by the working device are combined. An engine control device for a work vehicle, characterized in that: In the engine control device for a work vehicle according to claim 1,
An engine control device for a work vehicle, further comprising means for detecting a load of the engine and, when there is no load, a means for setting the engine to a minimum unloaded speed.

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