JP4064019B2 - Engine control device for construction machinery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine control device provided in a construction machine such as a hydraulic excavator, and more particularly to an engine control device for a construction machine that reduces a target engine speed when an actuator is inactivated.
[0002]
[Prior art]
A construction machine such as a hydraulic excavator generally includes a diesel engine as a prime mover, and a hydraulic pump is driven to rotate by the engine, and a hydraulic actuator is driven by pressure oil discharged from the hydraulic pump to perform necessary work.
[0003]
Further, the operator moves the operation lever and the pedal, guides the pilot hydraulic pressure from the pilot pump to the direction switching valve, and controls the operation of the hydraulic actuator by moving the direction switching valve.
[0004]
An input means such as an engine control dial is provided for the diesel engine, and a target engine speed is indicated by the engine control dial. The instruction of the engine control dial is given as a voltage and input to the controller. The controller obtains the target rotational speed of the diesel engine by calculation based on the instruction (voltage), controls the fuel injection amount according to the target rotational speed, and controls the engine rotational speed.
[0005]
In a conventional engine control device for construction machinery, it is common to cause the engine rotation to directly follow the target rotational speed indicated by the engine control dial.
[0006]
On the other hand, what performs engine control called auto-idle control is known, and an example thereof is disclosed in Japanese Patent Laid-Open No. 10-12003. The outline of the auto idle control is as follows.
[0007]
(1) When operating the hydraulic actuator, rotate the engine at the target speed indicated by the engine control dial.
[0008]
(2) When the hydraulic actuator is deactivated, the engine rotation up to that time is maintained for a certain time (for example, 3.5 seconds), and then the engine rotation is rapidly reduced to a target rotation speed (for example, 1200 rpm) for auto idle.
[0009]
(3) When the hydraulic actuator is actuated again, the engine speed is increased again to the target speed indicated by the engine control dial.
[0010]
[Problems to be solved by the invention]
However, the above prior art has the following problems.
[0011]
In the conventional general engine control device that directly follows the engine speed to the target speed indicated by the engine control dial, when the engine speed is in the high speed range and the operator is not operating the hydraulic excavator. ,
1) Since the engine speed is high even when the hydraulic actuator is inactive, fuel is wasted;
2) High engine speed, high engine cooling fan speed, and noise
The problem occurs.
[0012]
In an engine control apparatus that performs auto idle control as disclosed in Japanese Patent Laid-Open No. 10-12003, the engine rotation is automatically reduced to the idle rotation speed after a certain period of time has elapsed after the actuator has not been operated. There is no problem like 2). However, in the auto idle control, the engine speed is reduced to the idle speed. Therefore, when the target speed indicated by the engine control dial is a high speed such as the rated speed, the amount of decrease in the engine speed increases. As a result, the amount of increase at the time of engine rotation recovery also increases,
3) It makes it easier for the operator to feel changes in the engine speed, giving the operator a sense of incongruity;
4) If the actuator is restarted while the hydraulic actuator is under load, the engine speed will increase while the engine is under load, so the engine will suddenly blow up and black smoke will be mixed into the engine exhaust;
Cause problems.
[0013]
It is an object of the present invention to reduce the engine speed during non-operation, reduce fuel consumption and noise, reduce uncomfortable feeling when the engine speed changes, have a good operation feeling, and generate less black smoke after the start of operation. An engine control device is provided.
[0014]
[Means for Solving the Problems]
(1) In order to achieve the above object, the present invention provides an operation detection for detecting an operation of an engine, a rotation speed instruction means for instructing a target rotation speed of the engine, and an actuator hydraulically driven by the engine. And when the actuator is deactivated, the target rotational speed of the engine is lowered to the first rotational speed, and when the actuator is activated, the target rotational speed of the engine is returned to the target rotational speed instructed by the rotational speed instruction means. An engine control device for a construction machine that includes a first rotation speed control unit and controls the rotation speed of the engine according to a final target rotation speed;When the target rotational speed instructed by the rotational speed instruction means is higher than the predetermined second rotational speed,When the actuator is deactivated, the target engine speed is higher than the first engine speed.SaidA second rotational speed control means for lowering the target rotational speed of the engine to a target rotational speed instructed by the rotational speed instruction means when the actuator operates, and a target of the first rotational speed control means Rotational speedSaid first rotational speed asAnd the target rotational speed of the second rotational speed control meansSaid second rotational speed asSelecting means for selecting any one of them and setting it as the final target rotational speed.The selecting means does not select the second rotational speed when the actuator is inactivated when the target rotational speed instructed by the rotational speed instructing means is lower than the second rotational speed. The first rotation speed is selected as the final target rotation speedIt is characterized by that.
[0015]
In this way, the second rotational speed control means and the selection means are provided, and either the target rotational speed of the first rotational speed control means or the target rotational speed of the second rotational speed control means is selected and set as the final target rotational speed. Thus, when the target rotational speed of the second rotational speed control means is selected, when the actuator is deactivated, the engine rotational speed is lowered to a second rotational speed higher than the first rotational speed, so that fuel consumption and noise can be reduced. At the same time, the lowering amount of the engine rotation and the increasing amount at the time of returning to the engine rotation are reduced, so that the uncomfortable feeling at the time of engine rotation change is reduced and the operation feeling is improved. In addition, since the amount of increase at the time of returning to engine rotation is reduced, even if the operation of the actuator is resumed while the actuator is loaded, the sudden increase in engine speed is alleviated and the generation of black smoke is reduced.
[0016]
(2) In the above (1), preferably, the second rotational speed control means gradually lowers the target rotational speed of the engine when the actuator is deactivated.
[0017]
This makes it possible to smoothly reduce the engine speed, making it difficult for the operator to understand changes in the engine speed. This further reduces the sense of incongruity when the engine speed decreases, and improves the operational feeling.
[0018]
(3) In the above (1) or (2), preferably, the second rotational speed control means lowers the target rotational speed of the engine after a certain period of time when the actuator is inoperative.
[0019]
As a result, if the actuator is not operated for a certain period of time, the engine speed will not decrease, so if a neutral state occurs momentarily due to reciprocating operation levers such as gravel smashing or earth smashing, the engine speed will decrease. It is possible to avoid making the operator feel bad.
[0020]
(4) In the above (1) to (3), preferably, the second rotational speed control means is a predetermined rotational speed that is lower than a rated rotational speed and higher than the first rotational speed as the second rotational speed. Is set in advance, and when the target rotational speed indicated by the rotational speed instruction means is higher than the second rotational speed and the actuator is deactivated, the target rotational speed of the engine is set to the predetermined rotational speed. To lower.
[0021]
Thus, by setting the predetermined rotational speed to a rotational speed that can secure a certain amount of work, when the target rotational speed instructed by the rotational speed instruction means is higher than the second rotational speed, the engine speed The number does not decrease below the predetermined rotation number, and workability and work amount equivalent to the case where the engine rotation number is not decreased can be ensured.
[0022]
(5) In the above (1) to (3), the second rotational speed control means sets in advance a reduction amount of the target rotational speed of the engine, and when the actuator is inoperative, the target of the engine The rotational speed may be lowered by the lowering amount.
[0023]
As a result, regardless of the target rotational speed indicated by the rotational speed instruction means, control by the second rotational speed control means can be performed, and the lowering amount is set within a range that does not give the operator a sense of incongruity. As described above, the feeling of strangeness at the time of engine rotation change is reduced, and the operation feeling is improved.
[0024]
(6) In the above (1) to (3), preferably, the apparatus further includes an input unit that selects whether or not the control by the first rotation speed control unit is performed, and the selection unit includes the input unit that When the control by the first rotational speed control means is selected, the smaller one of the target rotational speed of the first rotational speed control means and the target rotational speed of the second rotational speed control means is selected.
[0025]
Accordingly, when the input means selects to perform the control by the first rotation speed control means, the smaller the target rotation speed of the first rotation speed control means and the target rotation speed of the second rotation speed control means by the selection means. Therefore, the combination of the control by the first rotation speed control means and the control by the second rotation speed control means can be performed. When the actuator is deactivated, the second rotation speed higher than the first rotation speed in advance. The engine speed is lowered to the second speed, and then the engine speed is lowered to the second speed. As a result, fuel efficiency is improved and noise is reduced.
[0026]
(7) Further, in the above (1) to (3), preferably, the second rotational speed control means gradually returns to the target rotational speed instructed by the rotational speed instruction means when the actuator is operated.
[0027]
This makes it possible to return the engine speed smoothly and makes it difficult for the operator to understand changes in the engine speed. This further reduces the sense of incongruity when returning to the engine speed, and improves the operational feeling. Moreover, the generation of black smoke at the time of engine rotation recovery is further reduced.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiment, a hydraulic excavator will be described as an example of a construction machine.
[0029]
In FIG. 1, reference numeral 1 denotes a swash plate type variable displacement hydraulic pump provided as a main pump. The hydraulic pump 1 is connected to a hydraulic actuator 3 via a direction switching valve 2. The pressure oil discharged from the hydraulic pump 1 is supplied to the hydraulic actuator via the direction switching valve 2, and the direction and flow rate of the pressure oil supplied to the actuator 3 is controlled by operating the direction switching valve 2. To control the operation. The hydraulic actuator 3 is an actuator such as a boom cylinder that drives the front of a hydraulic excavator, for example, and performs necessary work by controlling the operation of the hydraulic actuator 3.
[0030]
Reference numeral 5 denotes a fixed displacement pilot pump. A pilot relief valve 6 is provided in the discharge passage 5a of the pilot pump 5, and the discharge pressure of the pilot pump 5 is maintained at a constant pressure.
[0031]
The direction switching valve 2 is a pilot switching type, and is switched by a pilot pressure from the operation lever device 7. The operating lever device 7 has an operating lever 7a and a pair of pilot valves (reducing valves) 7b and 7c. When the operating lever 7a is operated, the corresponding pilot valve 7b or 7c is operated according to the operating direction. Based on the discharge pressure of the pilot pump 5, a pilot pressure corresponding to the operation amount of the operation lever 7a is generated.
[0032]
That is, when the operator moves the operation lever 7a and lowers the pilot valve 7b, the pilot pressure generated by the pilot valve 7b moves the main spool 2a of the direction switching valve 2 to the right in the figure, and moves the piston 3a of the hydraulic actuator 3 downward in the figure. Move to. When the operator moves the operation lever 7a and lowers the pilot valve 7c, the pilot pressure generated by the pilot valve 7c moves the main spool 2a of the direction switching valve 2 to the left in the figure and moves the piston 3a of the hydraulic actuator 3 upward in the figure. .
[0033]
The hydraulic pump 1 and the pilot pump 5 are connected to the output shaft 11 of the prime mover 10 and are rotationally driven by the prime mover 10.
[0034]
The prime mover 10 is a diesel engine, and the fuel injection amount is controlled by moving the governor lever 12 of the mechanical governor mechanism with the motor 13, and the engine rotation is controlled.
[0035]
The above-described hydraulic drive device is provided with the engine control device of the present invention. This engine control device has an engine control dial 20 that instructs a target rotational speed of the engine 10, and an instruction signal of the engine control dial 20 is given as a voltage and inputted to a controller 21. The controller 21 calculates a target rotational speed of the engine 10 by calculation, controls the motor 13 according to the target rotational speed, and moves the governor lever 12. The rotational speed of the engine 10 varies depending on the load received from the main hydraulic pump 1. When the engine speed fluctuates, the mechanical governor mechanism operates and maintains the target speed indicated by the engine control dial 20.
[0036]
Further, the engine control device has a mode switch 22 for selecting whether or not to perform auto idle control, and a pressure switch 23 for detecting the operation of the actuator 3 by detecting the pressure of the signal line 24. These signals are also controlled by the controller. 21 is input.
[0037]
The mode switch 22 can be switched between an OFF position and an ON position. When switched to the ON position, the mode switch 22 outputs an ON signal and selects auto idle control.
[0038]
One end of the signal line 24 for detecting the pressure by the pressure switch 23 is connected to the discharge passage 5a of the pilot pump 5 through the fixed throttle 25, and the other end is connected to the sub spool 26 that is linked to the main spool 2a of the direction switching valve 2. Via the tank 15. The sub-spool 26 is in the open position A when the direction switching valve 2 is in the neutral position, and the hydraulic fluid in the signal line 24 is caused to flow into the tank 15 by causing the signal line 24 to communicate with the tank 15. Use tank pressure (low pressure). Further, the sub spool 26 moves to the closed positions B and C when the direction switching valve 2 is switched from the neutral position, cuts off the communication between the signal line 24 and the tank 15, and discharges the pressure of the signal line 24 from the pilot pump 5. Increase to pressure (high pressure).
[0039]
Thereby, when the hydraulic actuator 3 is in an inoperative state, the pressure of the signal line 24 is low, and when the hydraulic actuator 3 is in an activated state, the pressure of the signal line 24 is high, and the hydraulic actuator 3 is in an inoperative state. Since the pressure of the signal line 24 changes from the low pressure to the high pressure when the hydraulic actuator 3 changes from the low pressure state to the high pressure state, and the pressure of the signal line 24 changes from the high pressure to the low pressure when the hydraulic actuator 3 changes from the active state to the low pressure state. The operation of the actuator 3 can be detected by detecting the pressure of 24.
[0040]
The processing functions of the controller 21 are shown in a functional block diagram in FIG.
[0041]
In FIG. 2, the controller 21 has functions of an auto idle control unit 21a, an ecology control unit 21b, and a minimum value selection unit 21c.
[0042]
The processing function of the auto idle control unit 21a is shown in a flowchart in FIG. The auto idle control unit 21a performs the following steps 1 to 6.
[0043]
Step 1
An engine control dial 20 instruction signal (hereinafter referred to as a dial instruction signal), a mode switch 22 signal (hereinafter referred to as a mode switch signal), and a pressure switch 23 signal (hereinafter referred to as a pressure switch signal) are input.
[0044]
Step 2
It is determined whether or not the mode switch signal is ON. If it is not ON, it is recognized that auto idle control is not selected, and the process proceeds to step 3. If it is ON, it is recognized that auto idle control is selected and the process proceeds to step 4. .
[0045]
Step 3
The target rotational speed of the auto idle control unit 21a is set as the target rotational speed indicated by the dial instruction signal. That is,
NOA = Na
NOA: Target rotational speed of the auto idle control unit 21a
Na: Target rotation speed for dial instructions
Step 4
It is determined whether or not the pressure switch signal is OFF. If it is not OFF, it is recognized that the hydraulic actuator 3 is in an operating state, and the process proceeds to step 3; move on.
[0046]
Step 5
It is determined whether or not a predetermined time, for example, 5 seconds has elapsed since the pressure switch signal was turned off. If the predetermined time has not elapsed, the process proceeds to step 3, and if the predetermined time has elapsed, the process proceeds to step 6.
[0047]
Step 6
The target rotation speed of the auto idle control unit 21a is set to 1200 rpm for the auto idle control. That is,
NOA = 1200 rpm
The processing function of the ecology control unit 21b is shown in a flowchart in FIG. The ecology control unit 21b performs the following steps 10 to 17.
[0048]
Step 10
A dial instruction signal and a pressure switch signal are input.
[0049]
Step 11
It is determined whether or not the indicated rotational speed of the dial instruction signal is an engine rotational speed that is a reference for ecology control, for example, 2000 rpm or more. If it is not 2000 rpm or more, the process proceeds to step 12;
[0050]
Here, the engine speed that is the standard for ecology control is a speed that can reduce fuel consumption and noise and secure a certain amount of work compared to when the engine speed is at the rated (maximum) 2200 rpm. 2000 rpm.
[0051]
Step 12
  The target rotation speed of the ecology control unit 21b is set as the instruction rotation speed of the dial instruction signal. That is, NOE = Na
NOE:Ecology control unit 21bTarget rotation speed
Na: Target rotation speed for dial instructions
Step 13
  It is determined whether or not the pressure switch signal is OFF. If it is not OFF, it is recognized that the hydraulic actuator 3 is in an operating state, and the process proceeds to step 12. If it is ON, it is recognized that the hydraulic actuator is in an inoperative state and the process proceeds to step 14. move on.
[0052]
Step 14
It is determined whether or not a predetermined time, for example, 1 second has elapsed since the pressure switch signal was turned off. If the predetermined time has not elapsed, the process proceeds to step 12; if the predetermined time has elapsed, the process proceeds to step 15.
[0053]
Step 15
The ecology control unit 21b determines whether or not the target rotational speed NOE calculated in the previous calculation cycle is 2000 rpm or more. If it is 2000 rpm or more, the process proceeds to step 16, and if it is not 2000 rpm or more, the process proceeds to step 17.
[0054]
Step 16
In order to gradually lower the target rotational speed of the ecology control unit 21b, a value obtained by subtracting the predetermined rotational speed ΔN from the NOE of the previous calculation cycle is set as the target rotational speed of the ecology control unit 21b. That is,
NOE = previous NOE−ΔN
Here, for example, if the calculation cycle time is 0.2 seconds, ΔN = 10 rpm is set. In this case, the engine speed decreases at a speed of 50 rpm / second.
[0055]
Step 17
The target rotational speed of the ecology control unit 21b is set to 2000 rpm. That is,
NOE = 2000rpm
The minimum value selection unit 21c selects the smaller one of the target rotation number NOA of the auto idle control unit 21a and the target rotation number NOE of the ecology control unit 21b calculated as described above, and sets it as the target rotation number of the controller 21. If the target rotational speed NOA and the target rotational speed NOE are equal, it may be determined in advance to select one of them, and in the present embodiment, it is determined to select the target rotational speed NOE for convenience. As a result, when the instruction signal of the mode switch 22 is OFF, the target rotational speed NOA of the auto idle control unit 21a becomes the target rotational speed Na of the dial instruction, and NAA ≧ NOE. Therefore, the target rotational speed of the controller 21 is the ecology control unit. The target rotational speed NOE is 21b.
[0056]
The operation of the engine control apparatus configured as described above will be described with reference to the time chart shown in FIG.
[0057]
In FIG. 5, (a) is a temporal change in the output of the pressure switch 23, where ON is when the hydraulic actuator 3 is operating and OFF is when the hydraulic actuator 3 is not operating. (B) is a temporal change of the target rotational speed NOE of the ecology control unit 21b, and is a temporal change of the target rotational speed of the controller 21 when the instruction signal of the mode switch 22 is OFF (when the automatic idle control is not selected). Match. (C) is a temporal change in the target rotational speed NOA of the auto idle control unit 21a when the instruction signal of the mode switch 22 is ON (when auto idle control is selected), and (d) is a target of the controller 21 at that time. This is a change in the rotational speed over time.
[0058]
When mode switch signal is OFF
When the instruction signal of the mode switch 22 is OFF, the target engine speed NOA of the auto idle controller 21a is the target engine speed Na instructed by the engine control dial 20 as described above, so that NOA ≧ NOE. The target rotational speed NOE of 21b becomes the target rotational speed of the controller 21. In this case, the ecology control unit 21b calculates the target rotational speed NOE as shown in FIG. 5B, and performs ecology control as follows.
[0059]
Ecology control
(1) When the engine control dial 20 indicates the rated 2200 rpm
1-1) It is assumed that the engine control dial 20 is operated to the maximum to indicate the rated target rotational speed of 2200 rpm. When the hydraulic lever 3 is operated by moving the operating lever 7a of the operating lever device 7 in this state, the target rotational speed becomes 2200 rpm with NOE = Na, and the engine 10 rotates at 2200 rpm.
[0060]
1-2) When the operation lever 7a is stopped from the above state and the hydraulic actuator 3 is deactivated, the target rotational speed is maintained at 2200 rpm for 1 second, and then the engine lowering speed is set to 50 rpm / second. Then, the target rotational speed decreases over 4 seconds from 2200 rpm to 2000 rpm, and similarly the rotational speed of the engine 10 also decreases.
[0061]
1-3) When the operation lever 7a is moved again from the above state and the hydraulic actuator 3 is operated, the target rotational speed becomes NOE = Na again and returns to 2200 rpm.
[0062]
(2) When the instruction of the engine control dial 20 is 2100 rpm
2-1) When the target rotation speed of 2100 rpm is instructed by the engine control dial 20, if the hydraulic actuator 3 is operated by moving the operation lever 7a of the operation lever device 7 in this state, the target rotation speed is NOE = Na The engine 10 rotates at 2100 rpm.
[0063]
2-2) When the operation of the operation lever 7a is stopped from the above state and the hydraulic actuator 3 is deactivated, the target rotation speed is maintained at 2100 rpm for 1 second, and then the engine lowering speed is set to 50 rpm / second. Then, the target rotational speed decreases over 2 seconds from 2100 rpm to 2000 rpm, and similarly the rotational speed of the engine 10 also decreases.
[0064]
2-3) When the operating lever 7a is moved again from the above state and the hydraulic actuator 3 is operated, the target rotational speed becomes NOE = Na again and returns to 2100 rpm.
[0065]
(3) When the instruction of the engine control dial 20 is 1900 rpm
3-1) When the target rotation speed of 1900 rpm is instructed by the engine control dial 20, when the hydraulic actuator 3 is operated by moving the operation lever 7a of the operation lever device 7 in this state, the target rotation speed is NOE = Na 1900 rpm, and the engine 10 rotates at 1900 rpm.
[0066]
3-2) Even if the operation of the operation lever 7a is stopped from the above state and the hydraulic actuator 3 is deactivated, the target rotational speed remains 1900 rpm, and the engine 10 continues to rotate at 1900 rpm.
[0067]
3-3) When the operation lever 7a is moved again from the above state to operate the hydraulic actuator 3, the target rotational speed remains 1900 rpm, and the engine 10 rotates at 1900 rpm.
[0068]
When mode switch signal is ON
When the instruction signal of the mode switch 22 is ON, the minimum value selection unit 21c selects the target rotation number NOA of the auto idle control unit 21a and the target rotation number NOE of the ecology control unit 21b to select the target rotation of the controller 21. In order to make it a number, control combining ecology control and auto idle control is performed. In this case, the change in the target rotational speed NOE calculated by the ecology control unit 21b is as shown in FIG. 5B as described above. The auto idle control unit 21a calculates the target rotational speed NOA as shown in FIG. 5 (c).
[0069]
Auto idle control
It is assumed that the engine control dial 20 is operated to the maximum to indicate the rated target rotational speed of 2200 rpm. In this state, when the operating lever 7a of the operating lever device 7 is moved to operate the hydraulic actuator 3, the target rotational speed becomes NOA = Na.
[0070]
When the operation of the operation lever 7a is stopped from the above state and the hydraulic actuator 3 is deactivated, the target rotational speed is maintained at 2200 rpm for 5 seconds, and then decreased to the target rotational speed 1200 rpm for auto idle control.
[0071]
When the operating lever 7a is moved again from the above state and the hydraulic actuator 3 is operated, the target rotational speed becomes NOA = Na again and returns to 2200 rpm.
[0072]
Ecology control + auto idle control
As shown in FIG. 5 (d), the minimum value selection unit 21c selects the smaller one of the target rotation speed NOA of the auto idle control section 21a and the target rotation speed NOE of the ecology control section 21b as the target rotation speed of the controller 21, Control combining ecology control and auto idle control is performed as follows.
[0073]
(1) When the engine control dial 20 indicates the rated 2200 rpm
1-1) It is assumed that the engine control dial 20 is operated to the maximum to indicate the rated target rotational speed of 2200 rpm. When the hydraulic lever 3 is operated by moving the operating lever 7a of the operating lever device 7 in this state, the target rotational speed becomes 2200 rpm with NOE = Na, and the engine 10 rotates at 2200 rpm.
[0074]
1-2) When the operation lever 7a is stopped from the above state and the hydraulic actuator 3 is deactivated, the target rotational speed is maintained at 2200 rpm for 1 second, and then the engine lowering speed is set to 50 rpm / second. In this case, the target rotational speed decreases from 2200 rpm to 2000 rpm over 4 seconds, and then decreases to the target rotational speed of 1200 rpm for auto idle control. Similarly, the rotational speed of the engine 10 also decreases.
[0075]
1-3) When the operating lever 7a is moved again from the above state and the hydraulic actuator 3 is operated, the target rotational speed becomes NOE = Na again and returns to 2200 rpm.
[0076]
(2) When the instruction of the engine control dial 20 is 2100 rpm
2-1) When the target rotation speed of 2100 rpm is instructed by the engine control dial 20, if the hydraulic actuator 3 is operated by moving the operation lever 7a of the operation lever device 7 in this state, the target rotation speed is NOE = Na The engine 10 rotates at 2100 rpm.
[0077]
2-2) When the operation of the operation lever 7a is stopped from the above state and the hydraulic actuator 3 is deactivated, the target rotation speed is maintained at 2100 rpm for 1 second, and then the engine lowering speed is set to 50 rpm / second. In this case, the target rotational speed decreases from 2100 rpm to 2000 rpm over 2 seconds, and then decreases to the target rotational speed of 1200 rpm for auto idle control. Similarly, the rotational speed of the engine 10 also decreases.
[0078]
2-3) When the operating lever 7a is moved again from the above state and the hydraulic actuator 3 is operated, the target rotational speed becomes NOE = Na again and returns to 2100 rpm.
[0079]
(3) When the instruction of the engine control dial 20 is 1900 rpm
3-1) When the target rotation speed of 1900 rpm is instructed by the engine control dial 20, when the hydraulic actuator 3 is operated by moving the operation lever 7a of the operation lever device 7 in this state, the target rotation speed is NOE = Na 1900 rpm, and the engine 10 rotates at 1900 rpm.
[0080]
3-2) Even if the operation of the operation lever 7a is stopped from the above state and the hydraulic actuator 3 is inactivated, the target rotational speed remains 1900 rpm, the target rotational speed is maintained at 1900 rpm for 5 seconds, and then auto idle control is performed. The target rotational speed decreases to 1200 rpm, and the rotational speed of the engine 10 also decreases.
[0081]
3-3) When the operation lever 7a is moved again from the above state and the hydraulic actuator 3 is operated, the target rotational speed becomes NOE = Na again and returns to 1900 rpm.
[0082]
As described above, in this embodiment, when the auto idle control is canceled by turning off the instruction signal of the mode switch 22, idle rotation is performed when the hydraulic actuator 3 is not operated for a certain period of time, that is, when the hydraulic excavator is not operated for a certain period of time. When the hydraulic excavator is operated, the engine speed is immediately returned to the target speed indicated by the engine control dial 20 by gradually lowering the engine speed to 2000 rpm (the speed at which a certain amount of work can be secured) higher than the number (1200 rpm). The following effects can be obtained.
[0083]
(1) When the hydraulic excavator is not operated, the engine speed can be lowered to reduce fuel consumption.
[0084]
(2) When the hydraulic excavator is not operated, the engine speed can be lowered to reduce noise.
[0085]
(3) If the hydraulic excavator is not operated for a certain period of time, the engine speed will not decrease. It is possible to avoid worsening the feeling for.
[0086]
(4) When the hydraulic excavator is not operated, the amount of decrease in engine speed is small, and as a result, the amount of increase when returning to engine speed is also small. I can do it well.
[0087]
(5) When the hydraulic excavator is not operated, the engine speed is gradually lowered, so that it becomes more difficult for the operator to feel a change in the engine speed, and the engine rotation feeling can be further improved.
[0088]
(6) When the hydraulic excavator is operated from the non-operating state, the amount of increase in the engine speed is small, so even if the hydraulic actuator 3 is under load, sudden engine blow-up is alleviated and black smoke is generated. To reduce.
[0089]
(7) When the hydraulic excavator is operated from the non-operating state, the amount of increase in the engine speed is small, so the response is good and the operability and workability are improved.
[0090]
(8) When the hydraulic excavator is operated from the non-operating state, the engine speed increases from 2000 rpm, which is a rotational speed that can secure a certain amount of work, so the same workability and work amount as when the engine speed is not lowered. Can be secured.
[0091]
Further, in this embodiment, when the instruction signal of the mode switch 22 is turned on and the auto idle control is turned on, the ecology control and the auto idle control are simultaneously performed. Therefore, when the hydraulic excavator is not operated for a certain time, the engine rotation After the number is gradually lowered, it is lowered to the target rotational speed of the auto idle control, thereby obtaining the following effects.
[0092]
(9) In the conventional auto idle control, when the excavator is not operated from the operating state, the engine rotation up to that time is maintained for a certain period of time (FIG. 5 (c)). Also grows. Compared to this, in the present embodiment, in combination with ecology control, fuel efficiency is improved and noise is reduced by gradually decreasing the engine speed.
[0093]
A second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, when the engine speed is decreased by ecology control, a decrease amount is determined in advance, and the decrease amount is gradually decreased.
[0094]
The device configuration of the engine control device and the functional configuration of the controller of the present embodiment are the same as those of the first embodiment. Among the functional configurations of the controller, the processing function of the ecology control unit 21b shown in FIG. Different from the embodiment.
[0095]
The processing function of the ecology control unit 21b is shown in a flowchart in FIG. The ecology control unit 21b performs steps 10 to 14, 15A, 16, and 17A. The processing in steps 10 to 14 and 16 is the same as that in the first embodiment shown in FIG. In steps 15A and 17A, the following processing is performed.
[0096]
Step 15A
The ecology control unit 21b determines whether or not a predetermined time, for example, 4 seconds has elapsed since proceeding to step 15A. If 4 seconds have not elapsed, proceed to step 16A, and if 4 seconds have elapsed, proceed to step 17A. .
[0097]
In step 16, as described above, in order to gradually lower the target rotational speed of the ecology control unit 21b, a value obtained by subtracting the predetermined rotational speed ΔN from the NOE of the previous calculation cycle is set as the target rotational speed of the ecology control unit 21b. . That is,
NOE = previous NOE−ΔN
Here, since the process of step 16 is continued for 4 seconds by step 15A, the accumulation of ΔN during that period becomes the amount of decrease in the target rotational speed. ΔN is set in such a range that the amount of decrease does not cause the operator to feel uncomfortable. For example, if the calculation cycle time is 0.2 seconds, ΔN = 10 rpm is set. In this case, the engine rotation decreases at a speed of 50 rpm / second, and the amount of decrease is 200 rpm.
[0098]
Step 17A
The target rotational speed of the ecology control unit 21b is set as the target rotational speed calculated in the previous calculation cycle. That is,
NOE = previous NOE
As described above, the minimum value selection unit 21c selects the smaller one of the target rotation speed NOA of the auto idle control section 21a and the target rotation speed NOE of the ecology control section 21b and sets it as the target rotation speed of the controller 21.
[0099]
The operation of the engine control apparatus configured as described above will be described with reference to the time chart shown in FIG. In FIG. 7, (b) and (d) operations relating to ecology control are different from those of the first embodiment.
[0100]
In the present embodiment, when the instruction signal of the mode switch 22 is OFF, as shown in FIG. 7B, the ecology control unit 21b calculates the target rotational speed NOE and performs ecology control.
[0101]
Ecology control
(1) When the engine control dial 20 indicates the rated 2200 rpm
1-1) It is assumed that the engine control dial 20 is operated to the maximum to indicate the rated target rotational speed of 2200 rpm. When the hydraulic lever 3 is operated by moving the operating lever 7a of the operating lever device 7 in this state, the target rotational speed becomes 2200 rpm with NOE = Na, and the engine 10 rotates at 2200 rpm.
[0102]
1-2) When the operation lever 7a is stopped from the above state and the hydraulic actuator 3 is deactivated, the target rotational speed is maintained at 2200 rpm for 1 second, and then the engine lowering speed is set to 50 rpm / second. Then, the target rotational speed decreases over 4 seconds from 2200 rpm to 2000 rpm, and similarly the rotational speed of the engine 10 also decreases.
[0103]
1-3) When the operating lever 7a is moved again from the above state and the hydraulic actuator 3 is operated, the target rotational speed becomes NOE = Na again and returns to 2200 rpm.
[0104]
(2) When the instruction of the engine control dial 20 is 2100 rpm
2-1) When the target rotation speed of 2100 rpm is instructed by the engine control dial 20, if the hydraulic actuator 3 is operated by moving the operation lever 7a of the operation lever device 7 in this state, the target rotation speed is NOE = Na The engine 10 rotates at 2100 rpm.
[0105]
  2-2) When the operation of the operation lever 7a is stopped from the above state and the hydraulic actuator 3 is deactivated, the target rotation speed is maintained at 2100 rpm for 1 second, and then the engine lowering speed is set to 50 rpm / second. Then, from 2100 rpm1900The target rotational speed decreases to 4 rpm over 4 seconds, and the rotational speed of the engine 10 also decreases.
[0106]
2-3) When the operating lever 7a is moved again from the above state and the hydraulic actuator 3 is operated, the target rotational speed becomes NOE = Na again and returns to 2100 rpm.
[0107]
(3) When the instruction of the engine control dial 20 is 1900 rpm
3-1) When the target rotation speed of 1900 rpm is instructed by the engine control dial 20, when the hydraulic actuator 3 is operated by moving the operation lever 7a of the operation lever device 7 in this state, the target rotation speed is NOE = Na 1900 rpm, and the engine 10 rotates at 1900 rpm.
[0108]
3-2) When the operation lever 7a is stopped from the above state and the hydraulic actuator 3 is deactivated, the target rotation speed is maintained at 1900 rpm for 1 second, and then the engine lowering speed is set to 50 rpm / second. Then, from 1900 rpm1700The target rotational speed decreases to 4 rpm over 4 seconds, and the rotational speed of the engine 10 also decreases.
[0109]
3-3) When the operation lever 7a is moved again from the above state and the hydraulic actuator 3 is operated, the target rotational speed becomes NOE = Na again and returns to 1900 rpm.
[0110]
When the instruction signal of the mode switch 22 is ON, as shown in FIG. 7 (d), the smaller one of the target rotational speed NOA of the auto idle control unit 21a and the target rotational speed NOE of the ecology control unit 21b is selected, Control combining ecology control and auto-idle control is performed.
[0111]
Ecology control + auto idle control
(1) When the engine control dial 20 indicates the rated 2200 rpm
1-1) It is assumed that the engine control dial 20 is operated to the maximum to indicate the rated target rotational speed of 2200 rpm. When the hydraulic lever 3 is operated by moving the operating lever 7a of the operating lever device 7 in this state, the target rotational speed becomes 2200 rpm with NOE = Na, and the engine 10 rotates at 2200 rpm.
[0112]
1-2) When the operation lever 7a is stopped from the above state and the hydraulic actuator 3 is deactivated, the target rotational speed is maintained at 2200 rpm for 1 second, and then the engine lowering speed is set to 50 rpm / second. In this case, the target rotational speed decreases from 2200 rpm to 2000 rpm over 4 seconds, and then decreases to the target rotational speed of 1200 rpm for auto idle control. Similarly, the rotational speed of the engine 10 also decreases.
[0113]
1-3) When the operating lever 7a is moved again from the above state and the hydraulic actuator 3 is operated, the target rotational speed becomes NOE = Na again and returns to 2200 rpm.
[0114]
(2) When the instruction of the engine control dial 20 is 2100 rpm
2-1) When the target rotation speed of 2100 rpm is instructed by the engine control dial 20, if the hydraulic actuator 3 is operated by moving the operation lever 7a of the operation lever device 7 in this state, the target rotation speed is NOE = Na The engine 10 rotates at 2100 rpm.
[0115]
2-2) When the operation of the operation lever 7a is stopped from the above state and the hydraulic actuator 3 is deactivated, the target rotation speed is maintained at 2100 rpm for 1 second, and then the engine lowering speed is set to 50 rpm / second. Then, the target rotational speed decreases from 2100 rpm to 1900 rpm over 4 seconds, and then decreases to the target rotational speed of 1200 rpm for auto idle control. Similarly, the rotational speed of the engine 10 also decreases.
[0116]
2-3) When the operating lever 7a is moved again from the above state and the hydraulic actuator 3 is operated, the target rotational speed becomes NOE = Na again and returns to 2100 rpm.
[0117]
(3) When the instruction of the engine control dial 20 is 1900 rpm
3-1) When the target rotation speed of 1900 rpm is instructed by the engine control dial 20, when the hydraulic actuator 3 is operated by moving the operation lever 7a of the operation lever device 7 in this state, the target rotation speed is NOE = Na 1900 rpm, and the engine 10 rotates at 1900 rpm.
[0118]
3-2) When the operation lever 7a is stopped from the above state and the hydraulic actuator 3 is deactivated, the target rotation speed is maintained at 1900 rpm for 1 second, and then the engine lowering speed is set to 50 rpm / second. Then, from 1900 rpm1700The target rotational speed decreases to 4 rpm over 4 seconds, then decreases to the target rotational speed of 1200 rpm for auto idle control, and similarly the rotational speed of the engine 10 also decreases.
[0119]
3-3) When the operation lever 7a is moved again from the above state and the hydraulic actuator 3 is operated, the target rotational speed becomes NOE = Na again and returns to 1900 rpm.
[0120]
Even with this embodiment configured as described above, the engine speed can be reduced during non-operation, fuel consumption and noise can be reduced, there is little uncomfortable feeling when the engine speed changes, and the operation feeling is good. The same effects as those of the first embodiment can be obtained, for example, occurrence can be reduced. Further, according to the present embodiment, the ecology control unit 21b can be controlled regardless of the target rotational speed indicated by the engine control dial 20.
A third embodiment of the present invention will be described with reference to FIGS. In the present embodiment, when the operation lever is operated, the target rotation speed is gradually returned to the target speed designated by the engine control dial.
[0121]
The device configuration of the engine control device and the functional configuration of the controller of the present embodiment are the same as those of the first embodiment. Among the functional configurations of the controller, the processing function of the ecology control unit 21b shown in FIG. Different from the embodiment.
[0122]
The processing function of the ecology control unit 21b is shown in a flowchart in FIG. The ecology control unit 21b performs steps 21 and 22 in addition to steps 10 to 17. The processing in steps 10 to 17 is the same as that in the first embodiment shown in FIG. However, in step 13, if the pressure switch signal is not OFF, it is recognized that the hydraulic actuator 3 is in an operating state, and the process proceeds to step 21. In steps 21 and 22, the following processing is performed. Note that when the controller power is turned on, NOE = Na until the pressure switch signal is first turned on and during the subsequent ON state (until the pressure switch signal is first turned off). Keep it.
[0123]
Step 21
When the pressure switch signal is ON, it is determined whether or not the target speed NOE calculated in the previous calculation cycle by the ecology control unit 21b is equal to or lower than the target speed Na indicated by the engine control dial 20 (previous NOE <Na). If Na or less, the process proceeds to step 22 for ending ecology control, and if Na or less, the process proceeds to step 12.
[0124]
Step 22
When the ecology control is finished, in order to smoothly increase the target rotational speed of the ecology control unit 21b, a value obtained by adding the predetermined rotational speed ΔN to the NOE of the previous calculation cycle is set as the target rotational speed of the ecology control unit 21b. That is,
NOE = previous NOE + ΔN
Here, ΔN is an increase speed until the engine speed returns to the target speed specified by the engine control dial by the processing in step 21 and is set so that the engine speed can be restored smoothly without being delayed too much. To do. For example, if the calculation cycle time is 0.2 seconds, ΔN = 40 rpm is set. In this case, the engine speed increases at a speed of 200 rpm / second.
[0125]
As described above, the minimum value selection unit 21c selects the smaller one of the target rotation speed NOA of the auto idle control section 21a and the target rotation speed NOE of the ecology control section 21b and sets it as the target rotation speed of the controller 21.
[0126]
The operation of the engine control apparatus configured as described above will be described with reference to the time chart shown in FIG. In FIG. 9, the operation at the time of resuming the operation of the part related to ecology control of (b) and (d) is different from that of the first embodiment.
[0127]
That is, in this embodiment, since the target rotational speed NOE of the ecology control unit 21b is set to NOE = previous NOE + ΔN in step 22 of FIG. 8 above, as shown in FIG. When ecology control is completed by re-operation, the target rotational speed NOE gradually increases at a constant speed, and the engine rotational speed smoothly increases to the target rotational speed instructed by the engine control dial 20. This makes it difficult for the operator to understand changes in the engine rotation, so that the engine rotation feeling can be further improved. Further, since the engine speed increases smoothly, the generation of black smoke when the engine rotation is restored is further reduced.
[0128]
Further, even in the control combining the auto idle control and the ecology control of FIG. 9D, when the auto idle control is ended by re-operation of the operation lever, the target rotational speed NOE gradually increases at a constant speed. However, since the engine speed does not increase rapidly and increases smoothly to the target speed specified by the engine control dial 20, it becomes difficult for the operator to understand the change in the engine speed. Smoke can be reduced.
[0129]
Therefore, according to the present embodiment, the same effects as those of the first embodiment can be obtained, the engine rotation feeling when the engine speed increases can be improved, and the black smoke in the exhaust gas can be reduced. .
[0130]
A fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, the present invention is applied to an engine having a fuel injection device having an electronic governor unit. In the figure, the same components as those shown in FIG.
[0131]
In FIG. 10, the engine 10 includes an electronic governor unit 30 as a fuel supply amount control means, and a controller 21 issues a command to the electronic governor unit 30 according to a target rotational speed obtained by calculation, and operates the electronic governor unit 30. Thus, the fuel injection amount is controlled, and the engine speed is controlled so that the target rotational speed is maintained.
[0132]
The processing function of the controller 21 is the same as that of the first embodiment or the same as that of the second or third embodiment.
[0133]
According to the present embodiment, the electronic governor unit 30 is provided as the fuel supply amount control means of the engine 10, and the same effects as those of the first embodiment or the second or third embodiment can be obtained.
[0134]
In the above embodiment, the engine control dial is exemplified as the engine target rotational speed instruction means. However, a throttle lever may be provided to detect the lever operation amount and indicate the engine target rotational speed. .
[0135]
【The invention's effect】
(1) According to the present invention, by the control (ecology control) by the second rotation speed control means, the engine speed can be reduced and fuel consumption and noise can be reduced during non-operation, and the engine rotation speed can be reduced by the first rotation speed control means. Since the engine speed is lowered to a second engine speed higher than the first engine speed (idle engine speed) of the control (auto idle control), the amount of decrease in the engine speed is reduced, and accordingly, the amount of increase at the time of returning to the engine speed is also reduced. , The feeling of strangeness when the engine speed changes is reduced, and the operation feeling is improved. Further, since the amount of increase at the time of returning to engine rotation is small, even if the operation of the actuator is resumed with a load applied to the actuator, the sudden blow-up of the engine is alleviated and the generation of black smoke is reduced.
[0136]
(2) When the engine is not operated, the engine speed is gradually reduced, so that the engine speed can be smoothly reduced, the feeling of strangeness when the engine speed is reduced is further reduced, and the operation feeling is improved.
[0137]
(3) If the engine is not operated for a certain period of time, the engine speed will not be reduced. Therefore, if a momentary neutral state occurs due to the reciprocating operation of the operating lever such as gravel smashing or earth smashing, the engine speed will decrease and the operator will It is possible to avoid worsening the feeling for.
[0138]
(4) Since the second rotational speed is set to a predetermined rotational speed and the target rotational speed indicated by the rotational speed instruction means is lower than the predetermined rotational speed when not operated, the second rotational speed is lowered to the predetermined rotational speed. The engine speed does not fall below the predetermined speed, and workability and work volume equivalent to the case where the engine speed is not lowered can be ensured.
[0139]
(5) Since the amount of decrease in the target engine speed of the engine is set in advance and the engine speed is decreased by the amount of decrease when the engine is not being operated, Control by the two-rotation speed control means can be performed, and the above effect is obtained.
[0140]
(6) Since control that combines control by the first rotation speed control means (auto idle control) and control by the second rotation speed control means (ecology) can be performed, up to a second rotation speed that is higher than the first rotation speed in advance. The engine speed is lowered, and then the engine speed is lowered to the second speed, resulting in improved fuel efficiency and reduced noise.
[0141]
(7) Since the engine speed is gradually returned to the target engine speed indicated by the engine speed instruction means at the time of operation, the engine speed can be returned smoothly, and the feeling of strangeness when the engine rotation is restored is further reduced, and the operation feeling is further improved. As well as being good, the generation of black smoke at the time of engine rotation recovery is further reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing an engine control device according to a first embodiment of the present invention, together with a hydraulic drive device provided in a construction machine such as a hydraulic excavator.
FIG. 2 is a block diagram illustrating a functional configuration of a controller.
FIG. 3 is a flowchart showing processing functions of an auto idle control unit in the controller.
FIG. 4 is a flowchart showing processing functions of an ecology control unit in a controller.
FIG. 5 is a time chart for explaining the operation of the engine control apparatus according to the first embodiment of the present invention.
FIG. 6 is a flowchart showing processing functions of an ecology control unit in a controller of an engine control apparatus according to a second embodiment of the present invention.
FIG. 7 is a time chart for explaining the operation of the engine control apparatus according to the second embodiment of the present invention.
FIG. 8 is a flowchart showing processing functions of an ecology control unit in a controller of an engine control apparatus according to a third embodiment of the present invention.
FIG. 9 is a time chart for explaining the operation of the engine control apparatus according to the third embodiment of the present invention;
FIG. 10 is a diagram showing an engine control apparatus according to a fourth embodiment of the present invention, together with a hydraulic drive apparatus provided in a construction machine such as a hydraulic excavator.
[Explanation of symbols]
1 Hydraulic pump (main pump)
2-way switching valve
3 Hydraulic actuator
5 Pilot pump
6 Pilot relief valve
7 Operation lever device
7a Operation lever
7b, 7c Pilot valve (pressure reducing valve)
10 Motor (diesel engine)
11 Output shaft
12 Governor lever
13 Motor
20 Engine control dial
21 Controller
22 Mode switch
23 Pressure switch
24 signal lines
25 Fixed aperture
26 Sub spool
21a Auto idle control unit
21b Ecology control unit
21c Minimum value selector

Claims (7)

An engine, an engine speed indicating means for instructing a target engine speed of the engine, an operation detecting means for detecting an operation of an actuator hydraulically driven by the engine, and a target engine speed of the engine when the actuator is inactivated. And a first rotation speed control means for returning the target rotation speed of the engine to the target rotation speed indicated by the rotation speed instruction means when the actuator is operated, according to the final target rotation speed In the engine control device for a construction machine that controls the rotational speed of the engine,
When the target rotational speed instructed by the rotational speed instructing means is higher than a predetermined second rotational speed , the target rotational speed of the engine is higher than the first rotational speed when the actuator is deactivated. said second lowered to the rotational speed, the second speed control means for returning the target revolution speed of the engine and the actuator is actuated to the target rotational speed instructing said rotational speed instructing means,
Either the first rotational speed as the target rotational speed of the first rotational speed control means or the second rotational speed as the target rotational speed of the second rotational speed control means is selected and the final target rotational speed is selected. and selection means for,
When the actuator is deactivated when the target rotational speed instructed by the rotational speed instructing means is lower than the second rotational speed, the selecting means does not select the second rotational speed and does not select the second rotational speed. An engine control device for a construction machine, wherein one rotation speed is selected as the final target rotation speed .   2. The engine control device for a construction machine according to claim 1, wherein the second rotation speed control means gradually decreases the target rotation speed of the engine when the actuator is inactivated. apparatus.   3. The engine control device for a construction machine according to claim 1, wherein the second rotation speed control means lowers the target rotation speed of the engine after a certain period of time when the actuator is deactivated. Engine control device for construction machinery.   The engine control device for a construction machine according to any one of claims 1 to 3, wherein the second rotational speed control means is a predetermined lower rotational speed than the first rotational speed as the second rotational speed. A rotation speed is set in advance, and when the target rotation speed indicated by the rotation speed instruction means is higher than the second rotation speed and the actuator is deactivated, the target rotation speed of the engine is set to the predetermined speed. An engine control device for a construction machine, wherein the engine speed is reduced to a rotational speed.   The engine control device for a construction machine according to any one of claims 1 to 3, wherein the second rotation speed control means sets in advance a reduction amount of the target rotation speed of the engine, and the actuator is inoperative. Then, an engine control device for a construction machine, wherein the target engine speed of the engine is lowered by the amount of reduction.   The engine control device for a construction machine according to any one of claims 1 to 3, further comprising input means for selecting whether or not to perform control by the first rotation speed control means, wherein the selection means includes the input means. When selecting to perform control by the first rotation speed control means, the smaller of the target rotation speed of the first rotation speed control means and the target rotation speed of the second rotation speed control means is selected. Engine control device for construction machinery.   The engine control device for a construction machine according to any one of claims 1 to 3, wherein the second rotation speed control means gradually returns to a target rotation speed instructed by the rotation speed instruction means when the actuator is operated. An engine control device for a construction machine.

Images