WO2016129196A1

WO2016129196A1 - Engine control device for working vehicle

Info

Publication number: WO2016129196A1
Application number: PCT/JP2015/086490
Authority: WO
Inventors: 田中　剛; 講介鬼束
Original assignee: ヤンマー株式会社
Priority date: 2015-02-09
Filing date: 2015-12-28
Publication date: 2016-08-18
Also published as: JP2016145566A

Abstract

Provided is an engine control device for a working vehicle, with which the necessary engine speed is achieved during work, and the desired output is achieved without complicated switching operations when the load on the engine is high during travel. An engine control device (50) equipped with a pressure switch (37), a controller (35), and an acceleration dial (36) for indicating the target engine speed of a diesel engine (34) to the controller (35), wherein: the controller (35) controls the engine speed according to the target engine speed when the pressure switch (37) detects that the working vehicle is traveling; and when the working vehicle is not traveling, the controller controls the engine speed according to the target engine speed while the target engine speed is equal to or less than an engine speed upper limit value set in advance, but controls the engine speed to be fixed at the engine speed upper limit value when the target engine speed is indicated to be greater than the engine speed upper limit value.

Description

Engine control device for work vehicle

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

In recent years, construction machines (work machines) such as hydraulic excavators have been required to have low noise and low fuel consumption, and work with the minimum required engine output to reduce the rotational noise and fuel consumption of the engine itself and accessories. The maximum engine speed tends to be suppressed to the necessary level so that the machine can perform work.

On the other hand, when the work machine is traveling, in order to achieve both traveling speed and driving force, a large hydraulic output may be required as compared to during work. For example, a construction machine including a device that increases or decreases the maximum discharge amount of a hydraulic pump as means for increasing or decreasing the hydraulic output when necessary is known (for example, see Patent Document 1).

In Patent Document 1, a variable displacement hydraulic pump driven by an engine and a device for controlling the movable swash plate of the hydraulic pump having a sufficient discharge amount to increase or decrease the discharge flow rate of the hydraulic pump are provided. It is equipped with a rotation speed control device and a work state detection device, and an operator is trying to realize driving of the actuator in accordance with the work state by selecting a combination of the maximum engine speed and the variable displacement hydraulic pump.

Japanese Patent Publication No. 05-17387

However, as in the technique described in Patent Document 1, in order to cope with a high hydraulic output, it is possible to cope by increasing the volume of the hydraulic system (pump) or increasing the pressure of the system. For this reason, there is a restriction on the mountability of equipment to be added to the vehicle, and there is a disadvantage in terms of manufacturing cost, so it cannot be easily handled. That is, with the technique described in Patent Document 1, a large increase in cost is caused by mounting a large-capacity pump, a variable pressure mechanism, a detection device, and the like, and in addition, there is a problem in mounting properties on these vehicles. In addition, the operator needs to select the optimal combination from among the above-mentioned combinations, and it is difficult to always select the optimal combination in a series of operations. It's not easy. In addition, there is a problem that a combination must be selected one by one when the load is high during driving and a powerful work is desired. In other words, there is a need for an engine control device for a work vehicle that can obtain the engine speed required when working with the work vehicle and can obtain a desired engine output without performing a troublesome switching operation when the engine is heavily loaded during traveling. Yes.

The present invention provides an engine control device for a work vehicle that can obtain an engine speed necessary for work and can obtain a desired engine output without performing troublesome switching work when the engine is heavily loaded during travel. It is aimed.

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

That is, the present invention
An engine,
A traveling device driven by the power of the engine;
Mounted on a work vehicle comprising a working device driven by the power of the engine,
In an engine control device for a work vehicle that controls the engine,
Traveling state detecting means for detecting a traveling state of the traveling device;
A controller for controlling the rotational speed of the engine;
An instruction device for instructing the target engine speed of the engine to the controller,
The controller is
If it is determined by the running state detecting means that the work vehicle is in a running state, the engine rotational speed of the engine is arbitrarily controlled according to the target engine rotational speed instructed to the controller by the instruction device,
On the other hand, when it is determined by the traveling state detection means that the work vehicle is not in the traveling state, if the target engine speed is less than a preset upper limit value of the engine speed, the engine engine according to the target engine speed is set. Control the rotation speed arbitrarily,
When the target engine speed is instructed to be greater than or equal to the upper limit value of the engine speed of the engine, control is performed so that the engine speed of the engine is fixed to the upper limit value of the engine speed.

The present invention relates to the engine control device,
The controller is
When it is determined by the traveling state detection means that the work vehicle is in a traveling state,
Control is arbitrarily performed below a preset upper limit value of the engine speed higher than the upper limit value of the engine speed.

In the engine control device according to the present invention, the pointing device is an accelerator dial.

As the effects of the present invention, the following effects are obtained.

According to the present invention, when the work vehicle is working, the engine speed at which the necessary engine output can be obtained is provided as the upper limit value, so that it is possible to prevent wasteful fuel consumption with low noise. On the other hand, when the engine is heavily loaded during traveling, a desired engine output can be obtained without troublesome switching work.

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 an accelerator dial. 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 the isochronous control which concerns on this embodiment. The performance curve figure which shows the control aspect in the case of performing droop control concerning this embodiment. (A) Performance curve diagram showing control mode when performing isochronous control from droop control, (b) Performance curve diagram showing control mode when performing droop control from isochronous control. The figure which shows the relationship between an engine speed and an accelerator opening sensor value.

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.
In addition, the turning operation | movement in the turning apparatus 3 can be mentioned as an example of a working state as operation | movement accompanying excavation work, for example.

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 working 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, one end of the boom 21 is supported by the front portion of the turning device 3, and is rotated by a boom cylinder 21a that 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.

The turning device 3 turns the work device 2. The swivel device 3 includes a swivel base 31, a hydraulic motor 32, and the like, and the hydraulic motor 32 drives the swivel base 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.

More specifically, the control unit 33 includes a control seat 331, an operation tool 332, a control panel, and the like. An operator sits on the control seat 331 and operates the operation tool 332, the control panel, and the like. To control the diesel engine 34. 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. 4) 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. A second traveling state detection means (not shown) configured by a switch or the like is disposed at the rotation base of the operation tool 332 to detect that the traveling operation has been performed.
The configuration of the traveling state detection unit and the arrangement position of the traveling state detection unit are not limited, and may be detected by a rotation sensor that detects the rotation of the axle. In the present embodiment, the configuration using the pressure switch 37 as the traveling state detection unit will be described in detail. However, a configuration using the second traveling state detection unit instead of the pressure switch 37 may be used. .

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.

The above is the overall configuration of the turning work vehicle 100, and the control mode of the diesel engine 34 will be described below.

First, a 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, which is a function of the engine speed N of the diesel engine 34 and the engine torque T, 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.

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

As shown in FIG. 2, 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 point X1 in FIG. 2), the engine control device 50 determines that the load on the diesel engine 34 has increased. The engine torque T is increased while maintaining the engine speed Nx of the diesel engine 34 constant (see point Xa2 in FIG. 2).

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 FIG. 2).

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 according to 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 rotational speed Nx (see the point X1 in FIG. 2), the controller 35 detects the diesel engine 34 when the load on the diesel engine 34 increases. The engine torque T is increased while gradually decreasing the engine speed N of the engine 34 (see point Xd2 in FIG. 2).

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 FIG. 2).

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

As shown in FIG. 3, the engine control device 50 is a switching unit for controlling a controller 35, an accelerator dial 36, a pressure switch 37 that is a traveling state detection unit, and an engine speed N of the diesel engine 34. A switching relay 38 is mainly provided. 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 is for performing control of the engine speed N of the diesel engine 34 and various other controls, and is mainly composed of a central processing unit, a storage device, and the like. The controller 35 is electrically connected to an accelerator dial 36, a pressure switch 37 that is a traveling state detection means, a switching relay 38, and the like, and based on an electrical signal input from the accelerator dial 36, the pressure switch 37, or the like. Create a control signal. 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 controller 35 receives output signals from various sensors such as an accelerator opening sensor (not shown) for performing various controls of the diesel engine 34.

The controller 35 stores a plurality of control patterns for isochronous control and control patterns for droop control in order to control the diesel engine 34 in response to an operator request. Then, the controller 35 selects an optimal control pattern from these control patterns according to the situation such as the work content and the running state, creates a control signal based on the selected control pattern, and outputs it to the diesel engine 34. To do. 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 for instructing the target engine speed of the diesel engine 34 to the controller 35. As shown in FIG. 4, the accelerator dial 36 can be set by the operator to manually rotate the dial 36 a to set the target engine speed, and the dial type (for adjusting the target engine speed of the diesel engine 34 ( This is a rotary switch. 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. A mechanical rotation angle as shown in FIG. 4 is set in advance in the accelerator dial 36 as an angle range in which the dial can be mechanically rotated manually by an operator. The position of the dial 36a set by the accelerator dial 36 (a predetermined angular position of the mechanical rotation angle) is output to the controller 35 as an electrical signal. Further, the accelerator dial 36 is electrically detected with an engine rotation speed “B” that is narrower than the mechanical rotation angle and smaller than the maximum value of the engine rotation speed N due to the mechanical rotation angle as an upper limit value. The electrical rotation angle to be performed is set in advance. As described above, in the present embodiment, the accelerator dial 36 has a predetermined angular difference between the mechanical rotation angle and the electrical rotation angle. In the electrical rotation angle, an engine speed “A” smaller than the engine speed “B” is also set in advance. Although details will be described later, when the operator operates the accelerator dial 36 to achieve a desired engine speed N, the controller 35 can obtain an output according to the traveling state and working state of the turning work vehicle 100. An engine speed N is set. For example, when the accelerator dial 36 is operated by the operator, the operation content (target engine speed set by the operator) is transmitted to the controller 35, and the controller 35 performs control based on the control flow according to a predetermined control flow. A signal is transmitted to the diesel engine 34, and the output of the diesel engine 34 is controlled.

The accelerator dial 36 is disposed 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 driving 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 may be 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 operation tool 332. The present embodiment is not particularly limited.

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 controls 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. Control the maximum number of revolutions N.
Note that the switching relay 38 is not an essential component in the engine control device 50, and is appropriately used as necessary.

The above is the configuration of the engine control apparatus 50 that controls the diesel engine 34. Next, the control flow of the engine control apparatus 50 will be described with reference to FIG. FIG. 6 is a performance curve diagram showing a control mode when performing isochronous control according to the present embodiment.

First, in step S101, the controller 35 determines whether the traveling device 1 of the turning work vehicle (this machine) 100 is in a traveling state or in a state other than traveling (for example, a stopped state). That is, the controller 35 determines whether or not the turning work vehicle 100 is traveling by the pressure switch 37 that is the traveling state detecting means.

Specifically, in step S101, the controller 35 determines whether the hydraulic pressure of the

hydraulic motors

12 and 12 is in a traveling state or a state other than traveling by using the pressure switch 37, and according to each of the states, the controller 35 It is determined how to set the engine speed N of the diesel engine 34.

When the controller 35 determines that the traveling device 1 is in a traveling state by the pressure switch 37, that is, the turning work vehicle 100 is traveling, the controller 35 proceeds to step S105, and the traveling device 1 is in a state other than traveling. For example, when it is determined that the traveling device 1 is stopped, the process proceeds to step S102.

In step S105, the controller 35 controls the engine speed N of the diesel engine 34 in accordance with the target engine speed instructed to the controller 35 by the accelerator dial 36. Specifically, in step S105, the controller 35 drives the diesel engine 34 according to an arbitrary target engine speed instructed to the controller 35 by the accelerator dial 36 when the engine speed N is equal to or lower than the engine speed “B”. Control to do. That is, the controller 35 changes the upper limit value of the engine speed N to the engine speed “B” only in the running state in order to ensure the running speed and driving force necessary for running. The controller 35 creates a control signal in accordance with the target engine speed designated by the accelerator dial 36 within the angle range of the electrical rotation angle (see FIG. 4) where the engine speed “B” is the upper limit value, and the created control. A signal is output to the diesel engine 34.

Specifically, in step S105, the controller 35 selects, from the control pattern stored in the controller 35, a second control pattern, which will be described later, for example, isochronous control with the engine speed “B” as an upper limit value. A control signal is generated based on the selected second control pattern. Then, the controller 35 outputs the created control signal to the diesel engine 34.

As a result, as shown in FIG. 6, in the traveling state of the traveling device 1 (YES in step S101), the second control pattern of the diesel engine 34 is selected, and the engine regardless of the increase or decrease of the load applied to the diesel engine 34. The isochronous control is performed so that the rotational speed N is constant, and the upper limit value of the engine rotational speed N of the diesel engine 34 is the engine rotational speed “B”.

Here, the second control pattern of the diesel engine 34 in which the engine speed “B” shown in FIG. 6 is the upper limit value is a control pattern used when the traveling device 1 of the turning work vehicle 100 is in the traveling state. . In the case of this second control pattern, the diesel engine 34 has an isochronous line b (a line where the engine speed N becomes the engine speed “B” even if the torque changes) and the maximum set for each engine speed N. Operation can be arbitrarily performed within a range surrounded by a torque curve Tcurve formed by connecting torque points. In the case of this second control pattern, the engine output becomes maximum at the maximum torque point at the engine speed “B” (maximum torque point on the isochronous line b: second rated output point). In other words, in the case of this second control pattern, the torque curve Tcurve is formed so that the diesel engine 34 has the maximum engine output at the maximum torque point at the engine speed “B”. For example, when the traveling device 1 of the turning work vehicle 100 shifts from a state other than traveling to a traveling state, the controller 35 changes the isochronous line a to the isochronous line b as shown in FIG. The upper limit value of the engine speed N is increased from the engine speed “A” to the engine speed “B”.

On the other hand, when it is determined that the traveling device 1 is not in the traveling state and the process proceeds to step S102, the following control flow is performed.

In step S102, the controller 35 determines in what state the position of the dial 36a by the accelerator dial 36, which is an instruction device for instructing the target engine speed. In other words, the controller 35 grasps the target engine speed indicated by the accelerator dial 36 and determines whether the target engine speed is equal to or higher than the engine speed “A” or lower than the engine speed “A”. To do.
In the present embodiment, the first control pattern of isochronous control with the engine speed “A” as the upper limit value and the isochronous control with the engine speed “B” higher than the engine speed “A” as the upper limit value. The second control pattern is stored in advance in the controller 35, and the controller 35 selects and instructs one of them according to the application conditions.

If the controller 35 determines that the target engine speed indicated by the accelerator dial 36 (simply referred to as the accelerator instruction speed) is equal to or higher than the engine speed “A”, the controller 35 proceeds to step S104. When it is determined that the engine speed is less than the engine speed “A”, the process proceeds to step S103.

In step S103, the controller 35 arbitrarily controls the engine speed N of the diesel engine 34 according to the target engine speed when the target engine speed is less than the engine speed “A” that is a preset upper limit value of the engine speed. To do. That is, in step S103, the controller 35 controls the diesel engine 34 to be driven at an arbitrary target engine speed that is less than the engine speed “A” and instructed by the accelerator dial 36. That is, the controller 35 normally controls the engine speed N so that the engine speed increases only to a necessary and sufficient engine speed “A” when working on the work device 2. The controller 35 creates a control signal in accordance with the target engine speed designated by the accelerator dial 36 within the angle range of the electrical rotation angle (see FIG. 4) where the engine speed “A” is the upper limit value, and the created control. A signal is output to the diesel engine 34. Thus, by providing the engine speed “A” as the upper limit value of the engine speed N that is necessary and sufficient at the time of work, low-noise and fuel-efficient work can be performed.

Specifically, in step S103, the controller 35 uses the control pattern stored in the controller 35 to perform the first control with the engine speed “A” as an upper limit, for example, isochronous control, as will be described in detail later. A pattern is selected, and a control signal is created based on the selected first control pattern. Then, the controller 35 outputs the created control signal to the diesel engine 34.

As a result, as shown in FIG. 6, when the traveling device 1 is in a state other than traveling (NO in step S101) and the target engine speed is less than the engine speed “A” (NO in step S102), the diesel engine The first control pattern 34 is selected, and isochronous control is performed in which the engine speed N is constant regardless of the increase or decrease in the load applied to the diesel engine 34. The upper limit value of the engine speed N of the diesel engine 34 is the engine speed. “A”.

Here, the first control pattern of the diesel engine 34 in which the engine speed “A” shown in FIG. 6 is an upper limit value is a state (for example, a stopped state) in which the traveling device 1 of the turning work vehicle 100 is not traveling. It is a control pattern used in the case. In the case of this first control pattern, the diesel engine 34 has an isochronous line a (a line where the engine speed N becomes the engine speed “A” even if the torque changes) and the maximum set for each engine speed N. Operation can be arbitrarily performed within a range surrounded by a torque curve Tcurve formed by connecting torque points. In the case of this first control pattern, the engine output becomes maximum at the maximum torque point at the engine speed “A” (maximum torque point on the isochronous line a: first rated output point). In other words, in the case of this first control pattern, the torque curve Tcurve is formed so that the diesel engine 34 has the maximum engine output at the maximum torque point at the engine speed “A”.

In step S104, when the target engine speed is instructed to be equal to or higher than the engine speed “A” that is the upper limit value of the engine speed N of the diesel engine 34, the controller 35 sets the engine speed “A” to the engine speed “A”. The engine speed N is controlled to be fixed. That is, the controller 35 is necessary when working on the work device 2 when the target engine speed designated by the accelerator dial 36 becomes the engine speed “A” and exceeds the engine speed “A”. The engine speed N is controlled so as to be fixed at a sufficient engine speed “A”. In step S <b> 104, the controller 35 creates a control signal so that the engine speed “A” becomes the target engine speed, and outputs the created control signal to the diesel engine 34. As described above, by controlling to prevent the engine speed “A” from exceeding the engine speed “A” as the upper limit value of the engine speed N that is necessary and sufficient at the time of work, the control is performed to fix the engine speed “A”. Work can be done.

Specifically, in step S104, the controller 35 selects and selects, from the control pattern stored in the controller 35, a first control pattern that is, for example, isochronous control and has the engine speed “A” as an upper limit value. A control signal is generated based on the isochronous line a of the first control pattern. Then, the controller 35 outputs the created control signal to the diesel engine 34.

As a result, as shown in FIG. 6, in a state other than traveling of the traveling device 1 (NO in step S101) and the target engine speed is equal to or higher than the engine speed “A” (YES in step S102), the diesel engine The first control pattern 34 is selected, and isochronous control is performed in which the engine speed N is constant regardless of the increase or decrease in the load applied to the diesel engine 34. The engine speed N of the diesel engine 34 is the engine speed “A”. Fixed to.
In the present embodiment, the first control pattern and the second control pattern of the isochronous control shown in FIG. 6 are described as examples of the control pattern, but the control pattern is not particularly limited. For example, instead of isochronous control, droop control is used, and as shown in FIG. 7, a first control pattern (with engine speed “A” as the upper limit value) and second control pattern (engine speed “B”). "B">"A"), the engine speed N of the diesel engine 34 can be controlled according to the control flow of the engine control device 50 described above. Specifically, for example, when the traveling device 1 of the turning work vehicle 100 shifts from a state other than traveling to a traveling state, the controller 35 changes the droop line a ₁ to the droop line b ₁ as shown in FIG. The upper limit value of the engine speed N is increased from the engine speed “A” to the engine speed “B” with the droop control.

Further, as shown in FIG. 8A, the first control pattern for droop control (engine speed “A” is set as the upper limit value) and the second control pattern for isochronous control (engine speed “B” is set as the upper limit value). It is also possible to control the engine speed N of the diesel engine 34 according to the control flow of the engine control device 50 described above as “B”> “A”). Specifically, for example, when the traveling device 1 of the turning work vehicle 100 shifts from a state other than traveling to a traveling state, as illustrated in FIG. 8A, the controller 35 performs droop control to isochronous control (droop control). The line a ₂ is changed to the isochronous line b ₂ ), and the upper limit value of the engine speed N is increased from the engine speed “A” to the engine speed “B”. By controlling in this way, it is possible to greatly increase the traveling speed.

Further, as shown in FIG. 8B, the first control pattern of isochronous control (engine speed “A” is the upper limit value) and the second control pattern of droop control (engine speed “B” is the upper limit value). It is also possible to control the engine speed N of the diesel engine 34 according to the control flow of the engine control device 50 described above as “B”> “A”). Specifically, for example, when the traveling device 1 of the turning work vehicle 100 shifts from a state other than traveling to a traveling state, as illustrated in FIG. 8B, the controller 35 performs droop control (isochronous control) from the isochronous control. The line a ₃ is changed to the droop line b ₃ ), and the upper limit value of the engine speed N is increased from the engine speed “A” to the engine speed “B”. By adopting such a control mode, even when the operator selects the droop control in which the load detection of the travel load is easy, the decrease in travel speed is reduced by increasing the engine speed.

Next, a specific control example of isochronous control (high idle control) of the diesel engine 34 during traveling by the engine control device 50 described above will be described with reference to FIG. FIG. 9 is a diagram showing the relationship between the engine speed and the accelerator opening sensor value, where the vertical axis is the engine speed (min ⁻¹ ) and the horizontal axis is the accelerator opening sensor value (V).
An accelerator opening sensor (not shown) includes an accelerator dial 36 and an accelerator operation lever that can be manually operated for setting a target engine speed of the engine speed N (that is, a fuel injection amount corresponding to the target engine speed). And the like, and is electrically connected to the controller 35. The accelerator opening sensor is configured to detect an operation amount of the accelerator operating member as an accelerator opening, and to input the detection signal to the controller 35 as an engine load.

The engine control device 50 normally sets the upper limit value of the engine speed N to the engine speed “A” described above, but the upper limit value of the engine speed N is set to the engine speed “B” described above when the traveling device 1 is traveling. To improve the running performance. When traveling, the engine speed “A” is assigned when the engine speed N corresponding to the accelerator opening sensor value a0 (V) is low idle and the accelerator opening sensor value a2 (V) is high idle. Above the voltage (accelerator opening sensor value a1 (V)), the engine speed N increases according to the accelerator opening. Further, this control is not performed when the other mode is valid. If this control example is made to correspond to the control mode described above, the upper limit value of the engine speed N is set to the engine speed “B” during traveling (in the case of YES in step S101). That is, when the accelerator opening sensor value is a1 to a2 (V), the engine speed N can be changed between the engine speed N of “A” to “B” min− ¹ . When the traveling device 1 is traveling, the upper limit value of the engine speed N is raised to the engine rotational speed “B”, while when the traveling device 1 is not traveling (NO in step S101), the engine The upper limit value of the rotational speed N is limited to the engine rotational speed “A”.

By adopting the control configuration of the engine control device 50 as described above, the engine speed is normally increased so that the engine speed only increases to a necessary and sufficient engine speed “A” when working on the work device 2 (a state other than traveling). By providing an upper limit to the number N, low noise and low fuel consumption work can be performed. Further, the upper limit value of the target engine speed is changed to the engine speed “B” higher than the engine speed “A” only in the running state. Thereby, the turning work vehicle 100 can ensure the traveling speed and driving force required for traveling.

Further, the engine control device 50 provides a difference between the mechanical rotation angle and the electric rotation angle of the accelerator dial 36, and sets the engine rotation speed “A” set before the maximum mechanical rotation angle during normal operation as an upper limit. Yes. Further, in the engine control device 50, only when the traveling state of the traveling device 1 is detected by the pressure switch 37 which is the traveling state detecting means and the electrical rotation angle of the accelerator dial 36 is larger than the engine rotational speed “A”, the engine rotation speed is increased. The target engine speed is instructed by the accelerator dial 36 with the number “B” as an upper limit. Thus, the engine control device 50 performs control to change the upper limit value of the engine speed N to an appropriate value according to the operation state (running state or working state) of the turning work vehicle 100.

Specifically, when the operator wants the traveling speed or driving force of the turning work vehicle 100 and appropriately operates the accelerator dial 36, the engine control device 50 sets the engine speed N as a preferred value. Can be changed. According to the present embodiment, control is performed so that the engine speed is increased to “B” as the upper limit value of the engine speed N of the diesel engine 34 only when high output is required, such as during travel. It is possible to provide an engine control device 50 that does not require such a large-capacity pump or the like, is inexpensive, can be easily operated by an operator, and can meet high output demands.

As described above, according to the present invention, since the engine speed at which the required engine output can be obtained when the work vehicle is working is provided as the upper limit value, it is possible to prevent wasteful fuel consumption with low noise. On the other hand, a desired engine output can be obtained without a troublesome switching operation at a high load during traveling, the vehicle can be driven powerfully, the traveling speed is high, and the operation can be performed without stress.

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

Claims

An engine,
A traveling device driven by the power of the engine;
Mounted on a work vehicle comprising a working device driven by the power of the engine,
In an engine control device for a work vehicle that controls the engine,
Traveling state detecting means for detecting a traveling state of the traveling device;
A controller for controlling the rotational speed of the engine;
An instruction device for instructing the target engine speed of the engine to the controller,
The controller is
If it is determined by the running state detecting means that the work vehicle is in a running state, the engine rotational speed of the engine is arbitrarily controlled according to the target engine rotational speed instructed to the controller by the instruction device,
On the other hand, when it is determined by the traveling state detection means that the work vehicle is not in the traveling state, if the target engine speed is less than a preset upper limit value of the engine speed, the engine engine according to the target engine speed is set. Control the rotation speed arbitrarily,
The work vehicle is controlled to fix the engine speed of the engine to the upper limit value of the engine speed when the target engine speed is instructed to be equal to or higher than the upper limit value of the engine speed of the engine. Engine control device.
The controller is
When it is determined by the traveling state detection means that the work vehicle is in a traveling state,
2. The engine control device for a work vehicle according to claim 1, wherein the control is arbitrarily performed below a preset upper limit value of the engine speed higher than the upper limit value of the engine speed.
3. The engine control device for a work vehicle according to claim 1, wherein the instruction device is an accelerator dial.