JP4437771B2 - Engine control device for traveling work machine - Google Patents

Description

  The present invention relates to an engine control device for a traveling work machine, and more particularly to an engine control device for a traveling work machine such as a wheel loader or a wheel excavator that uses both excavation and traveling work to the same extent.

  Construction machines such as hydraulic excavators and other traveling work machines generally include a diesel engine as a power source. In this diesel engine, a hydraulic pump is driven to rotate, and a hydraulic actuator is driven by the discharged oil to perform various operations. A diesel engine is provided with a fuel injection device, and the fuel injection amount is controlled by the fuel injection device to control the engine speed and output torque.

  The fuel injection device includes a mechanical control system called a mechanical governor and an electronic control system using an electronic governor. In an electronic control system using an electronic governor, an engine controller is used to control the electronic governor. The engine controller sets a target rotational speed based on an instruction from the operator, controls the fuel injection amount based on the target rotational speed, and controls the engine rotational speed and output torque.

  In addition, there is a controller that divides the engine controller into two controllers, an electronic governor controller and a vehicle body controller. In this case, the vehicle body controller sets a target rotational speed based on an operator's instruction and sends the signal to the electronic governor controller. The electronic governor controller controls the fuel injection amount based on the target rotational speed, and controls the engine rotational speed and the output torque.

  The engine output torque characteristic controlled in this way is divided into a fuel control region (partial load region) in which the fuel injection amount is controlled according to the load torque and a full load region in which the fuel injection amount is maximum. The characteristics of the control region (hereinafter referred to as engine rotation characteristics as appropriate) are usually set to droop characteristics. This droop characteristic simulates the characteristics of a mechanical governor, and is represented by a straight line with a constant slope that slopes downward from the maximum torque point (maximum fuel injection amount point) in the fuel control region in the engine torque characteristic diagram. The In this droop characteristic, the engine output torque increases along the straight line as the load torque increases, and the engine speed decreases as the engine output torque increases.

  On the other hand, in recent years, it has been proposed to set the engine rotation characteristic to a characteristic other than droop. A typical example of characteristics other than droop is isochronous characteristics. The isochronous characteristic is a characteristic represented by a vertical straight line with a gradient of zero in the engine torque characteristic diagram. In this isochronous characteristic, the engine speed is maintained at the target speed regardless of the engine load (change). The fuel injection amount is controlled.

  Japanese Patent Publication No. 62-8618, Japanese Patent Laid-Open No. 11-101183, and the like are publicly known documents disclosing droop characteristics. Known documents disclosing isochronous characteristics include Japanese Patent Application Laid-Open No. 10-89111 and WO03 / 001067A1.

Japanese Examined Patent Publication No. 62-8618 JP-A-11-101183 JP-A-10-89111 WO03 / 001067A1

  However, the above prior art has the following problems.

  In the prior art described above, it is common to fix the characteristic of the fuel control region (engine rotation characteristic) to either the droop characteristic or the isochronous characteristic. However, the operating state of a traveling work machine such as a wheel excavator can be either during traveling or during excavation / turning. If the engine rotation characteristics are fixed to one of the droop characteristics or isochronous characteristics, problems may occur depending on the operating conditions. May occur.

(1) When the engine rotation characteristic is fixed to the isochronous characteristic during traveling (a) The operator knows the uphill / downhill situation from the change in the engine speed, and estimates the brake braking distance. However, with isochronous characteristics, the engine speed does not change and the engine sound does not change, making it difficult to grasp the climbing and descending conditions.

  (B) Since traveling requires more engine torque than excavation, if the engine speed during traveling is controlled with isochronous characteristics, the required traveling performance will not be achieved unless the rated rotational speed is set larger than during excavation. Therefore, an engine having a larger displacement is required, resulting in a cost increase.

(2) When the engine rotation characteristic is fixed to the droop characteristic during excavation / turning (a) The engine speed fluctuates depending on the excavation / turning work load, and the flow rate of pressure oil from the hydraulic pump to the actuator changes. For this reason, the operation speed of excavation / turning changes, it becomes difficult to keep the excavation / turning speed constant, and the operability is lowered.

  (B) When the load is light, the engine speed increases and the engine noise increases. In particular, since work in an urban area or the like requires quietness, it is necessary to keep engine noise low.

  (C) When the load is light, the engine speed increases, so that the fuel consumption is deteriorated as compared with the control with isochronous characteristics.

  The purpose of the present invention is to change the engine rotation characteristics according to whether the vehicle is traveling or not traveling such as excavation / turning, so that the engine sound is changed according to the engine load state during traveling, and climbing / downhill conditions The engine speed increases to the required speed when running on land after start acceleration is completed, and the required speed can be obtained, and non-traveling such as excavation and turning The engine control device for a traveling work machine that has less fluctuations in operating speed when excavation / turning and other work loads fluctuate, has excellent operability, reduces engine noise, and improves fuel efficiency. Is to provide.

(1) To achieve the above Symbol object, the present invention includes an engine and a hydraulic pump driven by the engine, a working device driven by pressure oil from the hydraulic pump body driven by the engine In the engine control device for a traveling work machine having a traveling device for traveling the vehicle, a first engine control means for setting a target rotational speed based on an instruction from an operator, and a fuel injection amount based on the target rotational speed And second engine control means for controlling the rotational speed of the engine and travel detection means for detecting the travel of the vehicle body, wherein the first engine control means is based on the detection result of the travel detection means. It is determined whether the vehicle body is not running, and when the vehicle body is not running, an isochronous characteristic is instructed as an engine rotation characteristic to the second engine control means. When the vehicle is traveling, the vehicle has engine characteristic instruction means for instructing the second engine control means to have a droop characteristic as an engine rotation characteristic. The second engine control means is instructed by the first engine control means. Accordingly, control characteristic switching means for switching the control characteristic of the fuel injection amount is provided so that the engine rotation characteristic becomes either an isochronous characteristic or a droop characteristic.

  In the present invention configured as described above, since the engine rotation characteristic becomes a droop characteristic during traveling of the vehicle body, the engine sound is changed according to the load state of the engine so that the uphill / downhill situation can be grasped, and When the vehicle is traveling on the ground after the start acceleration is completed, the engine speed increases to the required speed, and the required travel speed can be obtained. Also, during non-running work (excavation / turning, etc.) using the work device, the engine rotation characteristics are isochronous, so there is little fluctuation in the operating speed when the work load such as excavation / turning fluctuates. In addition, the engine noise can be reduced and the fuel consumption can be improved.

( 2 ) In the above ( 1 ), preferably, the first engine control means causes the engine characteristic indicating means to switch the engine rotation characteristic between the isochronous characteristic and the droop characteristic with respect to the second engine control means. When instructing, it further has means for instructing the switching to be performed gradually, and the second engine control means responds to the instruction of the first engine control means when the control characteristic switching means switches the control characteristic. And a means for controlling the change of the control characteristic so that the engine rotation characteristic is gradually switched between the isochronous characteristic and the droop characteristic.

  Thus, when the droop characteristic is switched to the isochronous characteristic or vice versa, the switching is gradually performed, and the shock of the vehicle body due to the change in the engine speed can be reduced.

( 3 ) In the above ( 1 ), preferably, it further comprises work detection means for detecting work by the work device, wherein the first engine control means is based on detection results of the travel detection means and work detection means. It is determined whether or not a combined operation in which traveling of the vehicle body and work by the work device are performed at the same time, and when the engine characteristic instruction unit instructs the droop characteristic as the engine rotation characteristic to the second engine control unit, the combined operation And the second engine control means includes a means for instructing the slope of the droop characteristic to change in accordance with the combined degree of travel and work. The slope of the droop characteristic changes in accordance with an instruction from the first engine control means. In addition, there is further provided means for variably controlling the fuel injection characteristics.

  As a result, at the time of combined operation in which work by excavation / turning and other work devices is performed simultaneously, the slope of the droop characteristic changes according to the combined degree, and optimal engine control characteristics corresponding to the work situation can be obtained.

( 4 ) In the above ( 1 ), preferably, the first engine further includes a work detection means for detecting a work by the work device, and an operation means for inputting an external signal for adjusting the slope of the droop characteristic. The control means determines based on the detection results of the travel detection means and the work detection means whether or not it is a complex operation in which travel of the vehicle body and work by the work device are performed simultaneously, and the engine characteristic instruction means is the second engine When the droop characteristic is instructed to the control means as the engine rotation characteristic, there is further provided means for instructing the slope of the droop characteristic to change according to the composite degree of the running and work and the external signal during the combined operation. The second engine control means switches the control characteristic so that the control characteristic switching means uses the engine rotation characteristic as a droop characteristic. And a means for variably controlling the fuel injection characteristic so that the slope of the droop characteristic changes in accordance with an instruction from the first engine control means.

  This makes it possible to set the optimum slope of droop characteristics according to the work site, type of work, or operator's preference during single operation of traveling or combined operation in which traveling and excavation / turning work are performed simultaneously. It is possible to improve work efficiency and reduce operator fatigue.

  According to the present invention, the optimum droop characteristic slope according to the work site, the type of work, or the operator's preference, during a single operation of traveling or in a combined operation of simultaneously performing operations by a working device such as traveling and excavation / turning. Can be set, work efficiency can be improved, and operator fatigue can be reduced.

  Further, according to the present invention, when the droop characteristic is switched to the isochronous characteristic or vice versa, the switching is performed gradually, and the shock of the vehicle body due to the engine speed change can be reduced.

  Further, according to the present invention, during the combined operation in which the operation by the working device such as traveling and excavation / turning is performed simultaneously, the slope of the droop characteristic changes according to the combined degree, and the optimum engine control characteristic corresponding to the work situation is obtained. can get.

  Further, according to the present invention, the optimum droop characteristic according to the work site, the type of work, or the operator's preference at the time of a single operation of traveling or a combined operation of simultaneously performing operations by working devices such as traveling and excavation / turning Can be set, work efficiency can be improved, and operator fatigue can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a system configuration diagram including a hydraulic circuit of a construction machine equipped with an engine control apparatus according to a first embodiment of the present invention.

  In FIG. 1, reference numeral 1 denotes a diesel engine (hereinafter referred to as “engine”). The engine 1 rotationally drives a hydraulic pump 2 and a pilot pump 3 that are main pumps. The hydraulic pump 2 is connected to the hydraulic actuators 6 and 7 through the control valves 4 and 5, and when the control valves 4 and 5 are operated from the neutral position shown in the figure, the oil discharged from the hydraulic pump 2 is discharged from the control valves 3 and 4. Are supplied to the hydraulic actuators 6 and 7 to drive the hydraulic actuators 6 and 7. The control valves 3 and 4 are center bypass type control valves. When the control valves 3 and 4 are in the neutral position shown in the figure, the oil discharged from the hydraulic pump 2 is discharged from the center bypass line 8 and the center of each control valve 3 and 4. It returns to the tank 10 from the tank line 9 via the bypass passage.

  The hydraulic pump 2 is a variable displacement type and includes a pump regulator 11. The pump regulator 11 is, for example, a torque regulator that performs input torque restriction control. The pump regulator 11 inputs the discharge pressure of the hydraulic pump 2, and the input torque of the hydraulic pump 2 is a preset maximum torque with respect to the change of the discharge pressure of the hydraulic pump 2. The displacement (tilt) of the hydraulic pump 2 is controlled so as not to exceed.

  The pilot pump 3 is a fixed displacement hydraulic pump, and a pilot relief valve 12 is connected to the discharge line of the pilot pump 3 to keep the discharge pressure of the pilot pump 3 at a constant value (for example, 40 kg / cm 2). . The discharge line of the pilot pump 3 constitutes a pilot operating system hydraulic power source.

  Reference numerals 13 and 14 denote operation lever devices 13 and 14 provided in the pilot operation system. The operation lever devices 13 and 14 are respectively connected to the operation levers 13a and 14a and a pair of proportional pressure reducing valves 13b and 13c; 14b and 14c. It consists of and. When the operation lever 13a is operated, one of the proportional pressure reducing valves 13b and 13c is operated according to the operation direction, and when the operation lever 14a is operated, one of the proportional pressure reducing valves 14b and 14c is operated according to the operation direction, Each outputs a pilot pressure corresponding to the manipulated variable. These pilot pressures are transmitted to the control valves 4 and 5 via the pilot lines 15a and 15b; 16a and 16b, respectively, and the control valves 4 and 5 are switched from the neutral position.

  The hydraulic actuator 6 is an actuator related to excavation, and the hydraulic actuator 7 is an actuator related to traveling. When the construction machine is a wheel-type hydraulic excavator, the excavating actuator (hydraulic actuator 6) is a boom cylinder that drives the boom, an arm cylinder that drives the arm, a bucket cylinder that drives the bucket, and a turning motor that turns the swinging body. The travel-related actuator (hydraulic actuator 7) is a travel motor. In the following description, the hydraulic actuator 6 is appropriately referred to as an excavation actuator, and the hydraulic actuator 7 is referred to as a travel actuator as appropriate.

  The engine control apparatus according to the present embodiment is provided in the hydraulic system as described above, and includes an engine rotation instruction controller 21, an engine rotation control controller 22, an electronic governor 23, an engine control dial 24, a traveling pilot. A pressure sensor 25, a shuttle valve 26, and an engine speed sensor 27 are provided.

  The engine rotation instruction controller 21 inputs signals from the engine control dial 24 and the traveling pilot pressure sensor 25, performs predetermined calculation processing, and instructs the engine rotation control controller 22 to indicate the target rotation speed of the engine 1 and the engine rotation characteristics. The instruction signal is transmitted. The engine rotation controller 22 controls the electronic governor 23 based on the target rotation speed instruction signal, the engine rotation characteristic instruction signal, and the detection signal of the engine speed sensor 27 to control the fuel injection amount of the engine 1. . The engine 1 controls the engine speed and output torque by this fuel injection control.

  The engine control dial 24 is operated by an operator to indicate the target engine speed, and outputs an operation signal (voltage signal) corresponding to the operation position. The traveling pilot pressure sensor 25 detects the output pressure of the shuttle valve 26 and outputs a detection signal (voltage signal) indicating the output pressure. The shuttle valve 26 is provided on detection lines 28a and 28b branched from the pilot lines 16a and 16b, and detects the pilot pressure output when the operation lever device 14 is operated.

  FIG. 2 is a view showing an appearance of a wheel-type hydraulic excavator (wheel excavator). The wheel-type hydraulic excavator includes a lower traveling body 101, an upper swing body 102 that is rotatably mounted on the lower traveling body 101, and a front work machine 103. The lower traveling body 101 includes a front wheel 105 and a rear wheel 106, and these wheels 105 and 106 are driven by the traveling actuator 7 shown in FIG.

  The upper swing body 102 has a swing frame 109, and an operation room 110 and a machine room 111 on the swing frame 109. The engine room, the hydraulic pump 2, the pilot pump 3, etc. shown in FIG. Equipment is in place. The turning frame 109 is driven by a turning motor (not shown) and turns on the lower traveling body 101.

  The front work machine 103 includes a boom 113 rotatably connected to the revolving frame 109, an arm 114 rotatably connected to the tip of the boom 113, and a bucket rotatably connected to the tip of the arm 114. 115, and the boom 113, the arm 114, and the bucket 115 are driven by a boom cylinder 116, an arm cylinder 117, and a bucket cylinder 118, respectively. As described above, the excavation actuator 6 shown in FIG. 1 is one of the boom cylinder 116, the arm cylinder 117, the bucket cylinder 118, and a turning motor (not shown).

  FIG. 3 is a diagram schematically showing the control functions of the engine rotation instruction controller 21 and the engine rotation control controller 22.

  The engine rotation instruction controller 21 includes a target rotation number calculation unit 31, an engine rotation characteristic calculation unit 32, and a communication control unit 33. The engine rotation controller 22 includes a communication control unit 34, a switching control unit 35, an isochronous control unit 36, a droop control unit 37, and an output unit 38. The communication control unit 33 and the communication control unit 34 communicate with each other. They are connected via a line 39.

  The target rotational speed calculation unit 31 receives an operation signal from the engine control dial 24 and calculates a target rotational speed based on the operation signal. This target rotational speed may be sent to the communication control unit 33 as it is, or may be sent to the communication control unit 33 after being corrected (for example, for purposes such as auto idle control) as necessary.

  The engine rotation characteristic calculation unit 32 receives a detection signal (traveling pilot pressure) from the traveling pilot pressure sensor 25, determines the presence / absence of a traveling state based on the signal, and determines characteristics of the fuel control region (engine rotational characteristics) during traveling. ) Is a droop characteristic, and the engine rotation characteristic gain is switched so that the characteristic of the fuel control region (engine rotation characteristic) is an isochronous characteristic when not running.

  FIG. 4 is a diagram showing an output torque characteristic (engine torque characteristic) of the engine 1 controlled by the engine control apparatus of the present embodiment. In the figure, the horizontal axis represents the engine speed, and the vertical axis represents the engine output torque.

  The output torque characteristic of the engine 1 is divided into a fuel control region (partial load region) characteristic represented by a straight line 41-1 or a straight line 41-2 and a full load region characteristic represented by a curve 42. The fuel control region is a region in which the fuel injection amount of the electronic governor 23 is equal to or less than the maximum (100%), and the output torque is controlled by controlling the fuel injection amount according to the load torque of the engine 1. Is a state in which the fuel injection amount of the electronic governor 23 reaches the maximum (100%), and is an area balanced with the output torque by decreasing the engine speed with respect to an increase in load torque. In FIG. 4, a straight line 41-1 is an isochronous characteristic in which the straight line has a slope of 0, and a straight line 41-2 is a droop characteristic in which the straight line is inclined at a certain gradient. Further, in this specification, the characteristics of the straight line 41-1 or the straight line 41-2 are collectively referred to as “engine rotation characteristics”.

  FIG. 5 is a diagram showing details of the function of the engine rotation characteristic calculation unit 32. The engine rotation characteristic calculation unit 32 includes an isochronous gain setting unit 32a, a droop gain setting unit 32b, a traveling state determination unit 32c, and a switching unit 32d. In the isochronous gain setting unit 32a, the gain of the straight line 41-1, for example, “0” is set as the engine rotation characteristic gain. In the droop gain setting unit 32b, the gain of the straight line 41-2, for example, “3” is set as the engine rotation characteristic gain. When the signal (traveling pilot pressure) from the traveling pilot pressure sensor 25 is OFF, the traveling state determination unit 32c keeps the switching unit 32d at the OFF position shown in the figure, and when the signal from the traveling pilot pressure sensor 25 is turned on ( When the signal (voltage) from the traveling pilot pressure sensor 25 exceeds a predetermined value (dead zone), an ON signal is output to switch the switching unit 32d to the ON position. The switching unit 32d outputs the gain (eg, “0”) of the isochronous gain setting unit 32a when it is in the illustrated OFF position, and the gain (eg, “3”) of the droop gain setting unit 32b when switched to the OFF position. Output.

  Returning to FIG. 3, the communication control unit 33 converts the target rotation number calculated by the target rotation number calculation unit 31 and the engine rotation characteristic gain calculated by the engine rotation characteristic calculation unit 32 into data that can be communicated by CAN communication. The data is transmitted to the communication control unit 34 of the engine rotation control controller 22 via the communication line 39. The communication control unit 34 extracts the target rotation speed and the engine rotation characteristic gain from the received data and sends them to the switching control unit 35. The switching control unit 35 determines whether or not the engine rotation characteristic gain is “0”. If it is “0”, the target rotation number is sent to the isochronous control unit 36, and if it is not “0”, the target rotation number is drooped. The data is sent to the control unit 37.

  The isochronous control unit 36 controls the fuel injection amount so that the engine rotation characteristic becomes the isochronous characteristic, and the droop control unit 37 controls the fuel injection amount so that the engine rotation characteristic becomes the droop characteristic. As a result, the switching control unit 35 switches so that the control characteristic of the fuel injection amount is either isochronous control or droop control.

  FIG. 6 is a flowchart showing details of the control characteristic (function) of the isochronous control unit 36. First, a deviation (actual rotational speed−target rotational speed) ΔN between the rotational speed (actual rotational speed) of the engine 1 detected by the engine rotational speed sensor 27 and the target rotational speed is calculated, and whether ΔN> 0 (actual rotational speed). (Step S100), and if ΔN> 0, it is necessary to reduce the actual rotational speed, so control is performed to reduce the target fuel injection amount (step S120). This control may be, for example, integral control that reduces the target fuel injection amount by a certain rate, or may be a combination of integral control and differential control. If ΔN> 0 is not satisfied, it is further determined whether ΔN <0 (whether the actual rotational speed is smaller than the target rotational speed) (step S110). If ΔN <0, it is necessary to increase the actual rotational speed. Control is performed to increase the target fuel injection amount (step S130). This control may also be integral control, or a combination of integral control and differential control. If neither ΔN <0 nor ΔN <0, ΔN = 0 and the actual engine speed is equal to the target engine speed, so the current target fuel injection amount is maintained (step S140).

  The isochronous control unit 36 sends the target fuel injection amount calculated in this way to the output unit 38. The output unit 38 converts the target fuel injection amount into a control amount of the electronic governor 23 and outputs a command signal (electric signal) to the electronic governor 23. Thereby, the rotation speed of the engine 1 is controlled to be maintained at the target rotation speed regardless of the load torque (isochronous control).

  FIG. 7 is a diagram showing an output torque characteristic (engine rotation characteristic) of the engine 1 when the engine 1 is controlled by the target fuel injection amount calculated as described above. In the figure, the same parts as those shown in FIG. The straight lines 41-1a to 41-1d are engine rotation characteristics when the target rotation speeds are, for example, 2200 rpm, 2000 rpm, 1800 rpm, and 1600 rpm, respectively. These engine rotational characteristics are isochronous characteristics in which the slope of the straight line is zero.

  FIG. 8 is a diagram showing the fuel injection characteristics (relationship between the engine speed (actual speed) and the target fuel injection amount) of the table used for calculation by the droop control unit 37 when the target speed is 1600 rpm. In the figure, the horizontal axis represents the engine speed (actual speed), and the vertical axis represents the target fuel injection amount. The memory of the engine rotation control controller 22 stores a table in which fuel injection characteristics are set for each target rotation speed sent from the engine rotation instruction controller 21, and the droop control unit 37 reads the target rotation speed at that time. The table corresponding to is selected, and the target fuel injection amount is calculated with reference to the actual rotational speed at that time for the fuel injection characteristic of this table.

  When the target rotational speed is 1600 rpm, as shown by a straight line 45 in FIG. 8, the target fuel injection amount is minimum (MIN) when the actual rotational speed is larger than the target rotational speed of 1600 rpm, for example, 1800 rpm, and the actual rotational speed is less than that. The target fuel injection amount increases as it decreases, and when the actual rotational speed decreases to the target rotational speed of 1600 rpm, the relationship between the actual rotational speed and the target fuel injection amount is set so that the target fuel injection amount becomes maximum (MAX). ing. When the target rotation speed sent from the engine rotation instruction controller 21 is 2200 rpm, 2000 rpm, 1800 rpm, 1600 rpm, the table for the target rotation speed 2200 rpm, 2000 rpm, 1800 rpm is the same as the table shown in FIG. 8 for the target rotation speed 1600 rpm. The relationship between the engine speed (actual speed) and the target fuel injection amount is set.

  The droop control unit 37 sends the target fuel injection amount calculated using such a table to the output unit 38. The output unit 38 converts the target fuel injection amount into a control amount of the electronic governor 23 and outputs a command signal (electric signal) to the electronic governor 23. Thereby, the rotation speed of the engine 1 is controlled so as to increase as the load torque decreases with respect to the target rotation speed (droop control).

  FIG. 9 is a diagram showing an output torque characteristic (engine rotation characteristic) of the engine 1 when the engine 1 is controlled by the target fuel injection amount calculated as described above. In the figure, the same parts as those shown in FIG. The straight lines 41-2a to 41-2d indicating the engine rotation characteristics are those when the target rotation speed is, for example, 2200 rpm, 2000 rpm, 1800 rpm, or 1600 rpm, respectively. The engine rotation characteristic is a droop characteristic having a certain inclination (gradient) as represented by straight lines 41-2a to 41-2d. The slope of the droop characteristic corresponds to the slope of a straight line of the table set for each target rotational speed (a straight line showing the fuel injection characteristics in FIG. 8 when the target rotational speed is 1600 rpm).

  In the above, the front work machine 103 and the swing frame 109 shown in FIG. 3 constitute a work device driven by the pressure oil from the hydraulic pump 2, and the engine rotation instruction controller 21 and the engine control controller 22 are instructed by the operator. The engine speed is controlled based on the target engine speed, the fuel injection amount is controlled based on the target engine speed, and the engine control means is configured to control the engine speed. Body detection means for detecting the traveling of the body 101 and the upper turning body 102), an engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21, a switching control unit 35 of the engine controller 22, an isochronous control unit 36, a droop The control unit 37 determines whether the vehicle body is not running based on the detection result of the running detection means. Cross, and when the body of the non-traveling engine characteristic becomes isochronous characteristic, when the vehicle running, as the engine rotational characteristic is droop characteristic, constitute the control characteristics switching means for switching the control characteristic of the fuel injection amount.

  The engine rotation instruction controller 21 constitutes first engine control means for setting a target rotation speed based on an operator instruction, and the engine rotation control controller 22 controls the fuel injection amount based on the target rotation speed. The 2nd engine control means which controls the rotation speed of the engine 1 is comprised. The engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21 determines whether or not the vehicle body is not traveling based on the detection result of the traveling detection means (traveling pilot pressure sensor 25). An engine that instructs the second engine control means (engine rotation control controller 22) as an isochronous characteristic as an engine rotational characteristic, and directs a droop characteristic as an engine rotational characteristic to the second engine control means when the vehicle is traveling. The switching control unit 35, the isochronous control unit 36, and the droop control unit 37 of the engine control controller 22 constitute a characteristic instruction unit. The engine rotation characteristic is determined according to an instruction from the first engine control unit (engine rotation instruction controller 21). Fuel to be either isochronous or drooped Constituting a control characteristic switching means for switching the control characteristics of the injection amount.

  Next, the operation of the present embodiment configured as described above will be described.

<Drilling and turning>
The pilot pump 3 always supplies pressure oil to the operation lever device 13, and the control valve 4 is moved by operating the operation lever device 13 for the excavation actuator 6, so that the pressure oil flows into the excavation actuator 6, and the excavation actuator The front working machine 103 is moved by moving the piston No. 6, and excavation / turning work is performed.

  At this time, since the operating lever device 14 for the travel actuator 7 is not operated and no travel pilot pressure is generated, the detection signal of the travel pilot pressure sensor 25 is OFF.

  When the detection signal of the traveling pilot pressure sensor 25 is OFF, the engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21 outputs the gain (for example, “0”) of the isochronous gain setting unit 32a. As a result, the switching control unit 35 of the engine rotation controller 22 sends the target rotation number to the isochronous control unit 36, and the isochronous control unit 36 is shown in FIG. 6 based on the target rotation number at that time as described above. The target fuel injection amount is calculated by an algorithm (control characteristic). As a result, the rotational speed and output torque of the engine 1 are controlled as indicated by the straight lines 41-1a to 41-1d in FIG. 9, and the engine rotational characteristics are controlled to be isochronous at each target rotational speed (isochronous). control).

<During driving>
When the operating lever device 14 for the travel actuator 7 is operated, the control valve 5 moves, 7 oil flows into the travel actuator 6, the travel actuator 7 rotates, and a travel operation is performed.

  When the operating lever device 14 for the traveling actuator 7 is operated, the pilot pressure is detected by the traveling pilot pressure sensor 25, and the detection signal (ON) is input to the engine rotation instruction controller 21.

  When the detection signal of the traveling pilot pressure sensor 25 is ON, the engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21 outputs the gain (for example, “3”) of the droop gain setting unit 32b. As a result, the switching control unit 35 of the engine rotation controller 22 sends the target rotation number to the droop control unit 37, and the droop control unit 37 corresponds to the target rotation number at that time as shown in FIG. A target fuel injection amount is calculated according to the fuel injection characteristics. As a result, the engine speed and output torque of the engine 1 are controlled as indicated by the straight lines 41-2a to 41-2d in FIG. 9, and the engine speed characteristic is controlled to be the droop characteristic at each target speed (droop). control).

According to the present embodiment configured as described above, the following effects can be obtained.
(1) Effect of isochronous control during excavation (a) Since the engine speed does not fluctuate depending on the excavation load, the excavation / turning speed does not fluctuate. Therefore, the operator can adjust the operating speed of the front working machine (for example, bucket) by operating the operation lever device 13 without considering the excavation load, and excellent operability can be obtained.

  (B) Since the engine speed does not fluctuate due to the excavation load, noise generated by the engine 1 can be kept low.

(C) Since the engine speed does not fluctuate due to the excavation load, fuel consumption can be improved by keeping the engine speed at a light load low.
(2) Effects of droop control during travel (a) When the travel load is low, the engine speed is high, and when the travel load is high, the engine speed is low. For this reason, the operator can know the uphill / downhill situation by the change of the engine sound due to the change of the engine speed, and can determine the necessity of the brake or accelerator depressing operation and adjust the vehicle body speed.

  (B) It is possible to increase the engine speed at the time when the start acceleration is finished and the engine speed reaches a constant speed, and the engine speed at the time of constant land travel (light load travel), and a necessary speed can be obtained. For this reason, an engine with a small displacement can be employed.

  A second embodiment of the present invention will be described with reference to FIGS. 10, parts that are the same as the parts shown in FIG. 5 are given the same reference numerals. In FIGS. 11 and 12, parts that are the same as the parts shown in FIGS. 8 and 9 are given the same reference numerals. The overall configuration including the hydraulic system and the configuration of the control system in the engine control apparatus of the present embodiment are the same as those of the first embodiment shown in FIGS. 1 and 3, and in the following description, FIG. Reference is also made to FIG. In the present embodiment, when switching between the isochronous characteristic and the droop characteristic, the switching is performed gradually to reduce the shock of the vehicle body due to the change in the engine speed.

  As in the first embodiment, the engine control apparatus according to the present embodiment includes an engine rotation instruction controller 21 and an engine rotation control controller 22 (FIG. 1). The engine speed control unit 22 includes an engine speed characteristic calculation unit 32, a communication output unit 33, an engine speed control controller 22, a communication input unit 34, a switching control unit 35, an isochronous control unit 36, and a droop. A control unit 37 and an output unit 38 are provided, and the communication output unit 33 and the communication input unit 34 are connected via a communication line 39 (FIG. 3). However, the function of the engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21 and the function of the droop control unit 37 of the engine rotation control controller 22 are different from those of the first embodiment. The differences are as follows.

  FIG. 10 is a diagram showing details of the function of the engine rotation characteristic calculation unit 32 according to the present embodiment. The engine rotation characteristic calculation unit 32 includes an isochronous gain setting unit 32a, a droop gain setting unit 32b, a traveling state determination unit 32c, and a switching unit 32d, and a low-pass filter unit 32e and an engine rotation characteristic gain conversion unit 32f. Have.

  When the switching unit 32d switches the engine rotation characteristic gain from the isochronous characteristic gain to the droop characteristic gain, or when the switching unit 32d switches from the droop characteristic gain to the isochronous characteristic gain, the low pass filter unit 32e has a delay in the change of the gain. Smooth the transition (change).

  The engine rotation characteristic gain conversion unit 32f converts the gain processed by the low pass filter unit 32e into an engine rotation characteristic gain that can be used by the isochronous control unit 36 and the droop control unit 37 (FIG. 3) of the engine rotation control controller 22. . In the illustrated example, four gains of “0”, “1”, “2”, and “3” are set as the engine rotation characteristic gain. The gain “0” is for isochronous control, and the gains “1”, “2”, and “3” are for droop control.

  The droop control unit 37 of the engine controller 22 has a function of changing the slope of the droop characteristic corresponding to the gains “1”, “2”, and “3”.

  FIG. 11 shows the fuel injection characteristics (relationship between the engine speed (actual speed) and the target fuel injection amount) of the table used for calculation by the droop control unit 37 (FIG. 3) when the target speed is 2200 rpm. FIG. In the figure, the horizontal axis represents the engine speed (actual speed), and the vertical axis represents the target fuel injection amount. In the memory of the engine rotation control controller 22, fuel injection characteristics for different engine rotation characteristic gains are set for each target rotation speed (for example, every 1600 rpm, 1800 rpm, 2000 rpm, and 2200 rpm) sent from the engine rotation instruction controller 21. The table is stored, and the droop control unit 37 (FIG. 3) selects a table corresponding to the target rotation speed at that time, and refers to the engine rotation characteristic gain sent from the engine rotation instruction controller 21 to this table. Then, the corresponding fuel injection characteristic is selected, and the target fuel injection amount is calculated by referring to this fuel injection characteristic and the actual rotational speed at that time.

  In FIG. 11, straight lines 45-1, 45-2, and 45-3 are obtained when the engine rotation characteristic gain is “3”, “2”, and “1”, respectively. When the target engine speed is 2200 rpm and the engine speed characteristic gain is “3”, the target fuel injection amount is minimum (for example, 2400 rpm, where the actual engine speed is larger than the target engine speed 2200 rpm, as indicated by a straight line 45-1) ( MIN), the target fuel injection amount increases as the actual rotational speed decreases, and when the actual rotational speed decreases to the target rotational speed of 2200 rpm, the actual fuel injection amount reaches the maximum (MAX). The relationship between the number and the target fuel injection amount is set. When the engine speed characteristic gain is “2”, as shown by a straight line 45-2, the actual fuel speed is larger than the target speed 2200rpm, for example, 2340rpm, the target fuel injection amount is minimum (MIN), and the engine speed characteristics gain. When the engine speed is “1”, as shown by a straight line 45-1, the target fuel injection amount is minimum (MIN) when the actual engine speed is larger than the target engine speed of 2200 rpm, for example, 2270 rpm. The target fuel injection amount increases as it decreases, and when the actual rotational speed decreases to the target rotational speed of 2200 rpm, the relationship between the actual rotational speed and the target fuel injection amount is set so that the target fuel injection amount becomes maximum (MAX). ing. Similarly to the table of the target rotational speed 2200 rpm, the relationship between the engine rotational speed (actual rotational speed) and the target fuel injection amount for each engine rotational characteristic gain is set in the tables of the target rotational speed 2000 rpm, 1800 rpm, and 1600 rp.

  FIG. 12 is a diagram showing a change in the droop characteristic in the output torque characteristic of the engine 1 when the isochronous characteristic is switched to the droop characteristic when the target rotational speed is 2200 rpm, or when the droop characteristic is switched to the isochronous characteristic. .

  In FIG. 12, a straight line 41-1a is an isochronous characteristic with an inclination of 0, and straight lines 41-2a to 41-4a are droop characteristics inclined with a certain slope. The straight lines 41-1a to 41-4a are obtained when the engine rotation characteristic gain is “0”, “3”, “2”, and “1”, respectively. In the droop characteristic, the slope gradually increases.

  In the above, the low-pass filter unit 32e and the engine rotation characteristic gain conversion unit 32f in the engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21 and the droop control unit 37 including the table shown in FIG. When switching the control characteristic, a means for controlling the change of the control characteristic is configured so that the engine rotation characteristic is gradually switched between the isochronous characteristic and the droop characteristic.

  In addition, the low-pass filter unit 32e and the engine rotation characteristic gain conversion unit 32f in the engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21 provide the engine rotation characteristic to the second engine control means (engine rotation control controller 22) isochronously. When instructing to switch between the characteristics and the droop characteristics, a means for instructing the switching to be performed gradually is configured, and the droop control unit 37 having the table shown in FIG. Means for controlling the change in the control characteristic so that the engine rotation characteristic is gradually switched between the isochronous characteristic and the droop characteristic in accordance with an instruction from the first engine control means (engine rotation instruction controller 21). Constitute.

  In the first embodiment, when the engine rotational characteristic is switched from the droop characteristic to the isochronous characteristic or vice versa, the rotational speed of the engine 1 fluctuates. The fluctuation of the engine rotational speed is such that the load torque during operation is lower. Therefore, when the engine speed characteristic is switched, a change in the engine speed may be transmitted to the operator as a shock of the vehicle body. In the present embodiment, this point is improved, and when the isochronous characteristic and the droop characteristic are switched, the switching is gradually performed to reduce the shock of the vehicle body due to the change in the engine rotational characteristic.

  That is, in this embodiment, when the detection signal of the traveling pilot pressure sensor 25 switches from OFF to ON and switches from the isochronous characteristic to the droop characteristic, or the detection signal of the traveling pilot pressure sensor 25 switches from ON to OFF. When the droop characteristic is switched to the isochronous characteristic instead, the engine rotation characteristic gain indicated by the engine rotation instruction controller 21 by the low-pass filter unit 32e and the engine rotation characteristic gain conversion unit 32f is “0” → “1” → “2” → It gradually changes in the order of “3” or vice versa. The droop control unit 37 of the engine rotation controller 22 selects a fuel injection characteristic corresponding to the change in the engine rotation characteristic gain, and calculates a target fuel injection amount. As a result, the slope of the droop characteristic gradually changes as indicated by straight lines 41-2a to 41-4a in FIG. As a result, when the droop characteristic is switched to the isochronous characteristic or vice versa, the switching is gradually performed, and the shock of the vehicle body due to the change of the engine rotation characteristic can be reduced.

  A third embodiment of the present invention will be described with reference to FIGS. In this embodiment, the slope of the droop characteristic can be changed depending on the degree of combination of traveling and excavation / turning.

  FIG. 13 is a system configuration diagram including a hydraulic circuit of a construction machine equipped with an engine control apparatus according to the second embodiment of the present invention. In FIG. 13, the same components as those shown in FIG.

  In FIG. 13, the engine control apparatus according to the present embodiment includes an engine rotation instruction controller 21A and an engine rotation control controller 22A. Further, a drilling pilot pressure sensor 45 and a shuttle valve 46 are added to the configuration of the first embodiment shown in FIG. The shuttle valve 46 is provided in detection lines 47a and 47b branched from the pilot lines 15a and 15b, and detects the pilot pressure output when the operation lever device 13 is operated. The engine rotation instruction controller 21A inputs signals from the engine control dial 24, the traveling pilot pressure sensor 25, and the excavation pilot pressure sensor 45, performs predetermined calculation processing, and sets the target rotation speed of the engine 1 to the engine rotation control controller 22A. An instruction signal and an engine rotation characteristic instruction signal are transmitted.

  As in the first embodiment, the engine rotation instruction controller 21A includes a target rotation number calculation unit 31, an engine rotation characteristic calculation unit 32, and a communication output unit 33. The engine rotation control controller 22A includes a communication input. Unit 34, switching control unit 35, isochronous control unit 36, droop control unit 37, and output unit 38 (FIG. 3). Communication output unit 33 and communication input unit 34 are connected via communication line 39. It is connected. However, the function of the engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21A and the function of the droop control unit 37 of the engine rotation control controller 22A are different from those of the first embodiment. The differences are as follows.

  FIG. 14 is a diagram showing details of the function of the engine rotation characteristic calculation unit 32 (FIG. 3) in the engine rotation instruction controller 21A. The engine rotation characteristic calculation unit 32 includes a traveling pilot pressure gain calculation unit 32h, an excavation pilot pressure gain calculation unit 32i, a minimum value selection unit 32j, and an engine rotation characteristic gain conversion unit 32k.

  The traveling pilot pressure gain calculation unit 32h inputs a signal (traveling pilot pressure) from the traveling pilot pressure sensor 25, refers to the table stored in the memory, and corresponds to the traveling pilot pressure indicated by the signal at that time. The engine rotation characteristic gain is calculated. In the memory table, when the traveling pilot pressure is 0, the gain is also 0, and the relationship between the two is set so that the gain increases as the traveling pilot pressure increases. The gain when the traveling pilot pressure reaches around the maximum is, for example, “3” at the maximum.

  The excavation pilot pressure gain calculation unit 32i inputs a signal (excavation pilot pressure) from the excavation pilot pressure sensor 45, refers to the table stored in the memory, and corresponds to the traveling pilot pressure indicated by the signal at that time The engine rotation characteristic gain is calculated. In the memory table, the gain decreases as the drilling pilot pressure increases, and the relationship between the two is set so that the gain becomes zero when the drilling pilot pressure reaches the maximum. The gain when the excavation pilot pressure is near 0 is, for example, “3”.

  The minimum value selection unit 32j selects the smaller one of the gain calculated by the traveling pilot pressure gain calculation unit 32h and the gain calculated by the excavation pilot pressure gain calculation unit 32i, and outputs the selected one to the engine rotation characteristic gain conversion unit 32k.

  The engine rotation characteristic gain conversion unit 32k is the same as that of the second embodiment shown in FIG. 10, and the gain selected by the minimum value selection unit 32j is combined with the isochronous control unit 36 of the engine rotation control controller 22 and the droop. It is converted into an engine rotation characteristic gain that can be used by the control unit 37 (FIG. 3). In the illustrated example, as in the case of the second embodiment shown in FIG. 10, four gains of “0”, “1”, “2”, and “3” are set as the engine rotation characteristic gain. . The gain “0” is for isochronous control, and the gains “1”, “2”, and “3” are for droop control.

  The droop control unit 37 of the engine controller 22A has the same function as that of the second embodiment, and corresponds to the gains “1”, “2”, and “3” as shown in FIG. It has a function to calculate the target fuel injection amount using a table in which the injection characteristics (relationship between engine speed (actual speed) and target fuel injection amount) are set, and to change the slope of the droop characteristic as shown in FIG. is doing.

  In the above, the engine rotation instruction controller 21A and the engine control controller 22A set the target rotation speed based on the instruction from the operator, control the fuel injection amount based on the target rotation speed, and control the rotation speed of the engine 1. The engine control means comprises an engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21A, a switching control unit 35, an isochronous control unit 36, and a droop control unit 37 (FIG. 3) of the engine control controller 22A. Based on the detection result of the traveling pilot pressure sensor 25), it is determined whether or not the vehicle body is not traveling. When the vehicle body is not traveling, the engine rotation characteristic becomes an isochronous characteristic, and when the vehicle body travels, the engine rotation characteristic becomes a droop characteristic. In this way, the control characteristic switching means for switching the control characteristic of the fuel injection amount is configured. .

  The excavation pilot pressure sensor 45 constitutes work detection means for detecting work by the work device (the front work machine 103 and the turning frame 109), and a traveling pilot pressure gain calculation unit in the engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21A. 32h, a droop pilot pressure gain calculation unit 32i, a minimum value selection unit 32j, an engine rotation characteristic gain conversion unit 32k, and a droop control unit 37 having the table shown in FIG. Based on the detection results of the means, it is determined whether or not it is a combined operation in which the vehicle travels and the work by the work device is performed simultaneously, and during the combined operation, the slope of the droop characteristic changes according to the combined degree of the traveling and the work. A means for variably controlling the fuel injection characteristic is configured.

  The engine rotation instruction controller 21A constitutes first engine control means for setting a target rotation speed based on an operator instruction, and the engine rotation control controller 22A controls the fuel injection amount based on the target rotation speed. The 2nd engine control means which controls the rotation speed of the engine 1 is comprised. The engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21A determines whether or not the vehicle body is not traveling based on the detection result of the traveling detection means (traveling pilot pressure sensor 25). An engine characteristic indicating means for instructing an isochronous characteristic as an engine rotation characteristic to the second engine control means and instructing a droop characteristic as an engine rotation characteristic to the second engine control means when the vehicle travels, The switching control unit 35, the isochronous control unit 36, and the droop control unit 37 (FIG. 3) of the engine controller 22A have an engine rotational characteristic that is either an isochronous characteristic or a droop characteristic according to an instruction from the first engine control means. Thus, the control characteristic switching means for switching the control characteristic of the fuel injection amount is configured.

  The traveling pilot pressure gain calculation unit 32h, the excavation pilot pressure gain calculation unit 32i, the minimum value selection unit 32j, and the engine rotation characteristic gain conversion unit 32k in the engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21A include the traveling detection unit and the work detection. Based on the detection result of the means, it is determined whether or not it is a combined operation in which the vehicle travels simultaneously with the work by the work device, and the droop characteristic is set as the engine rotation characteristic for the second engine control means (engine rotation control controller 22A). When instructing, during the combined operation, means for instructing the slope of the droop characteristic to change in accordance with the combined degree of traveling and work is further configured, and the droop control having the table shown in FIG. 11 of the engine rotation controller 22A. The unit 37 uses the engine rotation characteristic as a droop characteristic. When switching the control characteristics, it constitutes a means for variably controlling the fuel injection characteristic as the inclination of the droop characteristic is changed according to an instruction of the first engine control unit (engine rotation instruction controller 21A).

  In the present embodiment configured as described above, in a single excavation / turning operation performed by operating only the operation lever 13, the excavation pilot pressure sensor 45 detects the excavation pilot pressure, and the engine of the engine rotation instruction controller 21 In the rotation characteristic calculation unit 32, an engine rotation characteristic gain of “0” is calculated in the traveling pilot pressure gain calculation unit 32h, and an engine rotation characteristic gain less than the maximum is calculated in the excavation pilot pressure gain calculation unit 32i. The selection unit 32j selects an engine rotation characteristic gain of “0”, and the engine rotation characteristic gain conversion unit 32k sets an engine rotation characteristic gain of “0”.

  In the engine rotation controller 22A, since the engine rotation characteristic gain is “0”, the isochronous control unit 36 (FIG. 3) calculates the target fuel injection amount by the algorithm shown in FIG. 6 based on the target rotation speed at that time. The fuel injection amount is controlled. Thus, the fuel control region is controlled to have the isochronous characteristic indicated by the straight line 41-1a in FIG.

  In the traveling-only operation performed only by operating the operation lever 14, the traveling pilot pressure sensor 25 detects the traveling pilot pressure, and the engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21 performs the operation in the traveling pilot pressure gain calculation unit 32h. Since the engine rotation characteristic gain of “0” or more is calculated and the maximum engine rotation characteristic gain is calculated in the excavation pilot pressure gain calculation unit 32i, the minimum engine selection unit 32j selects the maximum engine rotation characteristic gain, and the engine The rotation characteristic gain conversion unit 32k sets an engine rotation characteristic gain of “3”.

  In the engine rotation controller 22A, since the engine rotation characteristic gain is “3”, when the target rotation speed at that time is 2200 rpm in the droop control unit 37 (FIG. 3), this is indicated by the straight line 45-1. The target fuel injection amount is calculated based on the fuel injection characteristic, and the fuel injection amount is controlled. Accordingly, the slope of the droop characteristic is maximized as indicated by a straight line 41-2a in FIG. 12, and the fuel control region is controlled to have the maximum slope droop characteristic.

  On the other hand, when traveling and excavation / turning are performed by operating the operation lever devices 13 and 14 simultaneously, the traveling pilot pressure sensor 25 detects the traveling pilot pressure, the excavating pilot pressure sensor 45 detects the excavating pilot pressure, In the engine rotation instruction controller 21, an engine rotation characteristic gain corresponding to the traveling pilot pressure and the excavation pilot pressure is calculated in each of the traveling pilot pressure gain calculation unit 32h and the excavation pilot pressure gain calculation unit 32i of the engine rotation characteristic calculation unit 32. The smaller one is selected by the minimum value selection unit 32j, and the engine rotation characteristic gain conversion unit 32k converts the engine rotation characteristic gain to “1” or “2” corresponding to the selected gain. . That is, the engine rotation characteristic gain is set according to the combined degree of traveling and excavation / turning.

  In the engine rotation controller 22A, the droop control unit 37 (FIG. 3) calculates the target fuel injection amount based on the fuel injection characteristic according to the target rotation speed and the engine rotation characteristic gain at that time, as described above, and the fuel injection The amount is controlled. As a result, the slope of the droop characteristic changes as shown by straight lines 41-3a and 41-4a in FIG. 12 in accordance with the combined degree of traveling and excavation / turning. That is, when the combined degree of travel is greater than excavation / turning (when the operation amount of the operation lever device 14 is larger than the operation amount of the operation lever device 13), the straight line 41 having a smaller inclination than the straight line 41-2a of travel alone. -3a droop characteristics, and when the combined degree of excavation / turning is greater than the travel (when the operation amount of the operation lever device 13 is larger than the operation amount of the operation lever device 14), the slope is further inclined than the straight line 41-3a. It becomes the droop characteristic of the small straight line 41-4a.

  In the first embodiment, since the droop characteristic is set when the vehicle is traveling with or without the traveling pilot pressure (with the traveling pilot pressure), and the isochronous characteristic is used when the vehicle is not traveling (without the traveling pilot pressure), the combined traveling, excavation and turning are performed. Since there is a traveling pilot pressure, the drooping characteristic may occur and the excavation / turning feeling may deteriorate.

  According to the present embodiment, during the combined operation of traveling and excavation / turning, the slope of the droop characteristic changes depending on the degree of combination, and the optimum engine control characteristic corresponding to the work situation can be obtained.

In the above embodiment, the gain corresponding to each of the traveling pilot pressure and the excavation pilot pressure is calculated, and the gain corresponding to the combined degree of traveling and excavation / turning is set by selecting the minimum value. You may obtain | require the gain according to the compounding degree of driving | running | working and excavation / turning by other methods. For example, a gain corresponding to the combined degree of traveling and excavation / turning may be obtained by calculating a ratio between the traveling pilot pressure and the excavating pilot pressure and calculating a gain corresponding to the ratio. In addition, when traveling and excavation / turning are combined, it is noted that the traveling speed is slow, and the traveling speed may be obtained and the gain may be calculated from the traveling speed. Further, the gain according to the combined degree of traveling and excavation / turning may be obtained by combining the ratio of the traveling pilot pressure and the excavating pilot pressure and the traveling speed. The fourth embodiment of the present invention is shown in FIGS. It explains using. 15 and 16, parts that are the same as the parts shown in FIGS. 13 and 14 are given the same reference numerals. In FIGS. 17 and 18, parts that are the same as the parts shown in FIGS. The same reference numerals are attached. The overall configuration including the hydraulic system in the engine control apparatus of the present embodiment is the same as that of the third embodiment shown in FIG. 13, and the configuration of the control system is the same as that of the first embodiment shown in FIG. It is equivalent. In the present embodiment, the slope of the droop characteristic when traveling and excavation / turning are combined can be changed according to the preference of the operator and the type of work.

  FIG. 15 is a diagram showing a system configuration of the engine control apparatus according to the present embodiment. The engine control apparatus according to the present embodiment has an engine rotation instruction controller 21B and an engine rotation control controller 22B, and an external setting terminal 51 as a droop inclination adjusting apparatus is connected to the engine rotation instruction controller 21B. The external setting terminal 51 is an input device having a numeric keypad 51a and a display screen 51b. When the numeric keypad 51a is pressed, a corresponding signal is input to the engine rotation instruction controller 21B.

  As in the first embodiment, the engine rotation instruction controller 21B includes a target rotation number calculation unit 31, an engine rotation characteristic calculation unit 32, and a communication output unit 33. The engine rotation control controller 22B includes a communication input. Unit 34, switching control unit 35, isochronous control unit 36, droop control unit 37, and output unit 38 (FIG. 3). Communication output unit 33 and communication input unit 34 are connected via communication line 39. It is connected. However, the function of the engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21B and the function of the droop control unit 37 of the engine rotation control controller 22B are different from those of the first embodiment. The differences are as follows.

  FIG. 16 is a diagram showing details of the function of the engine rotation characteristic calculation unit 32 in the engine rotation characteristic instruction controller 21B. The engine rotation characteristic calculation unit 32 further includes a gain adjustment ratio setting unit 32m and a multiplication unit 32n with respect to the configuration of the third embodiment shown in FIG. Further, an engine rotation characteristic gain conversion unit 32p is provided instead of the engine rotation characteristic gain conversion unit 32k.

  The gain adjustment ratio setting unit 32m sets a gain adjustment ratio of 0 to 1 according to the numeric keypad signal input from the external setting terminal 51, and the multiplication unit 32n sets the gain adjustment ratio in the traveling pilot pressure gain calculation unit 32h. Multiply the calculated gain and output the multiplication value to the minimum value selection unit 32j. The minimum value selection unit 32j selects the smaller of the multiplication value of the multiplication unit 32n and the gain calculated by the excavation pilot pressure gain calculation unit 32i, and outputs the selected value to the engine rotation characteristic gain conversion unit 32p.

  The engine rotation characteristic gain conversion unit 32p converts the gain selected by the minimum value selection unit 32j into an engine rotation characteristic gain usable by the isochronous control unit 36 and the droop control unit 37 (FIG. 3) of the engine rotation control controller 22A. . In the illustrated example, seven gains of “0”, “0.5”, “1”, “1.5”, “2”, “2.5”, “3” are set as the engine rotation characteristic gain. ing. The gain “0” is for isochronous control, and the gains “0.5”, “1”, “1.5”, “2”, “2.5”, “3” are for droop control.

  The droop control unit 37 of the engine controller 22B adjusts the slope of the droop characteristic corresponding to the gains “0.5”, “1”, “1.5”, “2”, “2.5”, “3”. It has a function to change.

  FIG. 17 shows the fuel injection characteristics (relationship between engine speed (actual speed) and target fuel injection amount) of the table used for calculation by the droop control unit 37 (FIG. 3) when the target speed is 1600 rpm. FIG. In the figure, the horizontal axis represents the engine speed (actual speed), and the vertical axis represents the target fuel injection amount. In the memory of the engine rotation control controller 22B, fuel injection characteristics for different engine rotation characteristic gains are set for each target rotation speed (for example, every 1600 rpm, 1800 rpm, 2000 rpm, and 2200 rpm) sent from the engine rotation instruction controller 21B. The table is stored, and the droop control unit 37 (FIG. 3) selects a table corresponding to the target rotation speed at that time, and refers to the engine rotation characteristic gain sent from the engine rotation instruction controller 21 to this table. Then, the corresponding fuel injection characteristic is selected, and the target fuel injection amount is calculated by referring to this fuel injection characteristic and the actual rotational speed at that time.

  In FIG. 17, straight lines 45-1d, 45-2d, and 45-3d are fuel injection characteristics when the engine rotation characteristic gain is “3”, “2”, and “1”, respectively. Three straight lines between the characteristic straight lines are the fuel injection characteristics when the engine rotational characteristic gain is “2.5”, “1.5”, and “0.5”. When the target rotational speed is 1600 rpm and the engine rotational characteristic gain is “3”, the target fuel injection amount is minimum (for example, 1800 rpm, where the actual rotational speed is larger than the target rotational speed of 1600 rpm, as shown by a straight line 45-1d ( MIN), the target fuel injection amount increases as the actual rotational speed decreases, and when the actual rotational speed decreases to the target rotational speed of 1600 rpm, the actual fuel injection amount reaches the maximum (MAX). The relationship between the number and the target fuel injection amount is set. When the engine speed characteristic gain is “2”, as shown by a straight line 45-2d, the actual fuel speed is larger than the target speed 1600 rpm, for example, 1730 rpm, and the target fuel injection amount is minimum (MIN). Is “1”, as shown in a straight line 45-1d, the actual fuel speed is larger than the target engine speed of 1600 rpm, for example, 1660 rpm, and the target fuel injection amount is minimum (MIN). The target fuel injection amount increases as it decreases, and when the actual rotational speed decreases to the target rotational speed of 1600 rpm, the relationship between the actual rotational speed and the target fuel injection amount is set so that the target fuel injection amount becomes maximum (MAX). ing. Similarly, when the engine speed characteristic gain is “2.5”, “1.5”, and “0.5”, the fuel injection characteristics are set so that the actual engine speed at which the target fuel injection amount is minimized is sequentially decreased. Is set. The fuel injection characteristics for each engine rotational characteristic gain are set in the tables of the target rotational speeds 2200 rpm, 2000 rpm, and 1800 rpm as well as the table of the target rotational speed 1600 rpm.

  FIG. 18 shows the case where the engine speed characteristic gain changes to “3”, “2.5”, “2”, “1.5”, “1”, “0.5” when the target rotational speed is 1600 rpm. It is a figure which shows the change of the droop characteristic in the output torque characteristic of the engine 1.

  In FIG. 18, the straight lines 41-2d to 41-4d, the straight line between them, and the straight line between them and the straight line 41-1d (inclination 0) of the isochronous characteristic have engine rotation characteristic gains of “3” and “2”, respectively. .5 "," 2 "," 1.5 "," 1 ", and" 0.5 ", the droop characteristics are shown, and the slope gradually decreases.

  In the above, the external setting terminal 51 constitutes an operating means for inputting an external signal for adjusting the slope of the droop characteristic, and the traveling pilot pressure gain calculating unit 32h in the engine rotation characteristic calculating unit 32 of the engine rotation instruction controller 21B. The excavation pilot pressure gain calculation unit 32i, the minimum value selection unit 32j, the gain adjustment ratio setting unit 32m, the multiplication unit 32n, the minimum value selection unit 32j, the engine rotation characteristic gain conversion unit 32p, and the engine rotation control controller 22 shown in FIG. The droop control unit 37 having a table is used in the combined operation in which the vehicle body travels and the work device simultaneously performs based on the detection results of the travel detection means (travel pilot pressure sensor 25) and the work detection means (excavation pilot pressure sensor). In the combined operation, the combined degree of driving and work and external signal Depending constitute means for variably controlling the fuel injection characteristic as the inclination of the droop characteristic is changed.

  Further, the traveling pilot pressure gain calculation unit 32h, the excavation pilot pressure gain calculation unit 32i, the minimum value selection unit 32j, the gain adjustment ratio setting unit 32m, the multiplication unit 32n, the minimum value in the engine rotation characteristic calculation unit 32 of the engine rotation instruction controller 21B. The selection unit 32j and the engine rotation characteristic gain conversion unit 32p determine whether or not the second engine is in a combined operation in which traveling of the vehicle body and work by the work device are performed simultaneously based on detection results of the travel detection unit and the work detection unit. When the droop characteristic is instructed as the engine rotation characteristic to the control means (engine rotation controller 22B), during the combined operation, an instruction is given so that the slope of the droop characteristic changes according to the combined degree of travel and work and an external signal. The engine rotation controller 22B shown in FIG. When the droop control unit 37 having a control signal is switched so that the engine rotation characteristic becomes the droop characteristic, the slope of the droop characteristic changes in accordance with an instruction from the first engine control means (engine rotation instruction controller 21B). A means for variably controlling the fuel injection characteristic is configured.

  In the present embodiment configured as described above, the operator operates the numeric keypad 51a of the external setting terminal 51 to sequentially reduce the gain adjustment ratio set in the gain adjustment ratio setting unit 32m between 0 and 1. Thus, when traveling alone or when traveling and excavation / turning are combined, the multiplication value with the gain calculated by the traveling pilot pressure gain calculating unit 32h obtained by the multiplying unit 32n is reduced according to the gain adjustment ratio. When the gain is selected by the minimum value selection unit 32j, the selected gain is similarly reduced, and the gain converted by the engine rotation characteristic gain conversion unit 32p is also reduced accordingly. As a result, the slope of the fuel injection characteristic of the droop control unit 37 gradually decreases as shown by the arrow C in FIG. 17, and the slope of the droop characteristic also gradually decreases as shown by the arrow D in FIG. Thus, in the present embodiment, the operator can change the slope of the droop characteristic by operating the numeric keypad 51a of the external setting terminal 51.

  In the first embodiment, the slope of the droop characteristic is fixed at the time of traveling alone. In the third embodiment, the slope of the droop characteristic is changed depending on the combined degree of traveling and excavation / turning to improve the excavation / turning feeling. However, the droop characteristic (tilt) depends on the type of work and the preference of the operator. There is a case that it doesn't match and the work feeling is bad.

  According to the present embodiment, it is possible to set the optimum slope of the droop characteristic according to the work site, the type of work, or the operator's preference at the time of single operation of traveling or combined operation of traveling and excavation / turning. The working efficiency can be improved, and the operator's operational fatigue can be reduced.

  19 and 20 are diagrams showing a modification of the fourth embodiment. In this modification, a dial type adjustment switch 52 is provided as a droop inclination adjusting device instead of the numeric keypad type external setting terminal 51. The engine rotation characteristic calculation unit 32 in the engine rotation characteristic instruction controller 21C has a gain adjustment ratio calculation unit 32q instead of the gain adjustment ratio setting unit 32m of FIG. The gain adjustment ratio calculation unit 32q calculates a gain adjustment ratio of 0 to 1 according to the adjustment dial voltage signal from the adjustment switch 52, and the gain adjustment ratio is calculated by the traveling pilot pressure gain calculation unit 32h in the multiplication unit 32n. Multiply the gain. Other processes are the same as those in the fourth embodiment.

  Also in this embodiment, the same effect as that of the fourth embodiment can be obtained.

  While several embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made within the spirit of the present invention.

  For example, in the above embodiment, the pilot pressure sensor is used as the travel detection unit and the excavation detection unit. However, a sensor that detects the movement of the operation lever device may be used, or a sensor that detects the movement of the control valve is used. May be. If the operation lever device is electricity, the operation signal voltage input to the controller may be detected.

  In the above embodiment, the two controllers, the engine rotation instruction controller and the engine rotation control controller, are used, but it is needless to say that these may be integrated into one controller.

  Further, in the above-described embodiment, the engine rotation characteristic is used for switching the engine rotation characteristic between the isochronous characteristic and the droop characteristic, or the slope of the droop characteristic is changed, and the fuel according to the engine rotation characteristic gain is used. Coordinates of a plurality of points (for example, 6 points) that specify the engine output torque characteristics including the engine rotation characteristics in the fuel control area instead of the engine rotation characteristics gain, although the injection quantity control characteristics are switched or the fuel injection characteristics are selected. A value may be used to indicate the engine rotation characteristic with the coordinate values of the plurality of points.

1 is a system configuration diagram including a hydraulic circuit of a construction machine equipped with an engine control device according to a first embodiment of the present invention. It is a figure which shows the external appearance of a wheel-type hydraulic excavator (wheel excavator). It is a figure which shows the outline of each control function of an engine rotation instruction | indication controller and an engine rotation control controller. It is a figure which shows the output torque characteristic (engine rotation characteristic) of the engine controlled by the engine control apparatus of this Embodiment. It is a figure which shows the detail of a function of an engine rotation characteristic calculating part. It is a flowchart which shows the detail of the function (control characteristic) of an isochronous control part. It is a figure which shows the output torque characteristic (engine rotational characteristic) of an engine when an engine is controlled so that it may become an isochronous characteristic. It is a figure which shows the fuel-injection characteristic (relationship of an engine speed (actual speed) and target fuel injection quantity) of the table used for a calculation in a droop control part, when a target speed is 1600 rpm. It is a figure which shows the output torque characteristic (engine rotation characteristic) of an engine when an engine is controlled so that it may become a droop characteristic. It is a figure which shows the detail of the function of the engine speed characteristic calculating part in the engine control apparatus concerning the 2nd Embodiment of this invention. It is a figure which shows the fuel-injection characteristic of the table used for a calculation in a droop control part, when a target rotation speed is 2200 rpm. It is a figure which shows the change of the droop characteristic in the output torque characteristic of an engine when switching from an isochronous characteristic to a droop characteristic when a target rotation speed is 2200 rpm, or switching from a droop characteristic to an isochronous characteristic. It is a system block diagram containing the hydraulic circuit of the construction machine carrying the engine control apparatus concerning the 3rd Embodiment of this invention. It is a figure which shows the detail of the function of the engine rotation characteristic calculating part in an engine rotation instruction | indication controller. It is a figure which shows the system configuration | structure of the engine control apparatus concerning the 4th Embodiment of this invention. It is a figure which shows the detail of the function of the engine speed characteristic calculating part in an engine speed characteristic instruction | indication controller. It is a figure which shows the relationship between the engine rotational speed (actual rotational speed) of the table used for a calculation in a droop control part, and target fuel injection amount when a target rotational speed is 1600 rpm. Engine output when the engine speed characteristic gain changes to “3”, “2.5”, “2”, “1.5”, “1”, “0.5” when the target rotational speed is 1600 rpm It is a figure which shows the change of the droop characteristic in a torque characteristic. It is a figure which shows the system configuration | structure of the engine control apparatus concerning the modification of the 4th Embodiment of this invention. It is a figure which shows the detail of the function of the engine speed characteristic calculating part in an engine speed characteristic instruction | indication controller.

Explanation of symbols

1 Diesel engine (engine)
2 Hydraulic pump 3 Pilot pump 4, 5 Control valve 6, 7 Hydraulic actuator 8 Center bypass line 9 Tank line 10 Tank 11 Pump regulator 12 Pilot relief valve 13, 14 Operation lever device 15a, 15b; 16a, 16b Pilot line 21 Engine rotation Instruction controller 22 Engine rotation control controller 23 Electronic governor 24 Engine control dial 25 Travel pilot pressure sensor 26 Shuttle valve 27 Engine rotation speed sensors 28a, 28b Detection line 31 Target rotation speed calculation section 32 Engine rotation characteristic calculation section 32a Isochronous gain setting section 32b Droop gain setting unit 32c Traveling state determination unit 32d Switching unit 32e Low pass filter unit 32e
32h Traveling pilot pressure gain calculation unit 32i Excavation pilot pressure gain calculation unit 32j Minimum value selection unit 32k Engine rotation characteristic gain conversion unit 32m Gain adjustment ratio setting unit 32n Multiplication unit 32p Engine rotation characteristic gain conversion unit 32q Gain adjustment ratio calculation unit 32q
33 communication control unit 34 communication control unit 35 switching control unit 36 isochronous control unit 37 droop control unit 38 output unit 41-1 straight line 41-2 indicating the characteristic (isochronous characteristic) of the fuel control region characteristic of the fuel control region (droop characteristic) A straight line 42 showing a curve 45 showing a characteristic of the entire load region 45 Excavation pilot pressure sensor 46 Shuttle valves 47a, 47b Detection line 51 External setting terminal 51a Numeric keypad 52 Dial type adjustment switch

Claims (4)

Engine control of a traveling work machine comprising an engine, a hydraulic pump driven by the engine, a working device driven by pressure oil from the hydraulic pump, and a traveling device driven by the engine to travel the vehicle body In the device
First engine control means for setting a target rotational speed based on an operator instruction;
Second engine control means for controlling a fuel injection amount based on the target rotational speed and controlling the rotational speed of the engine;
Traveling detection means for detecting the traveling of the vehicle body,
The first engine control means determines whether or not the vehicle body is not running based on the detection result of the running detection means, and when the vehicle body is not running, the engine rotation characteristic with respect to the second engine control means An engine characteristic indicating means for instructing an isochronous characteristic, and for instructing a droop characteristic as an engine rotation characteristic to the second engine control means during traveling of the vehicle body,
The second engine control means includes control characteristic switching means for switching the control characteristic of the fuel injection amount so that the engine rotation characteristic becomes either an isochronous characteristic or a droop characteristic in accordance with an instruction from the first engine control means. An engine control device comprising: In the engine control device of the traveling work machine according to claim 1 ,
The first engine control means instructs the second engine control means to gradually change the engine rotation characteristic when switching the engine rotation characteristic between the isochronous characteristic and the droop characteristic. Further comprising means for
In the second engine control means, when the control characteristic switching means switches the control characteristic, the engine rotation characteristic is gradually switched between an isochronous characteristic and a droop characteristic in accordance with an instruction from the first engine control means. Thus, the engine control apparatus further comprises means for controlling the change in the control characteristic. In the engine control device of the traveling work machine according to claim 1 ,
It further comprises work detection means for detecting work by the work device,
The first engine control means determines whether or not it is a combined operation in which traveling of the vehicle body and work by the work device are simultaneously performed based on detection results of the travel detection means and the work detection means, and the engine characteristic instruction means When the droop characteristic is instructed as the engine rotation characteristic to the second engine control means, there is further provided means for instructing the slope of the droop characteristic to change according to the combined degree of travel and work during the combined operation. And
The second engine control means changes the slope of the droop characteristic in response to an instruction from the first engine control means when the control characteristic switching means switches the control characteristic so that the engine rotation characteristic becomes the droop characteristic. An engine control apparatus further comprising means for variably controlling the fuel injection characteristic. In the engine control device of the traveling work machine according to claim 1 ,
Work detection means for detecting work by the work device;
An operation means for inputting an external signal for adjusting the slope of the droop characteristic;
The first engine control means determines whether or not it is a combined operation in which traveling of the vehicle body and work by the work device are simultaneously performed based on detection results of the travel detection means and the work detection means, and the engine characteristic instruction means When instructing the droop characteristic as the engine rotation characteristic to the second engine control means, instructing the slope of the droop characteristic to change according to the composite degree of traveling and work and the external signal during the combined operation. Further comprising means,
The second engine control means changes the slope of the droop characteristic in response to an instruction from the first engine control means when the control characteristic switching means switches the control characteristic so that the engine rotation characteristic becomes the droop characteristic. An engine control apparatus further comprising means for variably controlling the fuel injection characteristic.

Images