JP2005023805A - Engine lug-down suppressing device for construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine lug-down suppressing device for a construction machine having a speed sensing control means quickening restoration to a target value of engine rotation speed when engine lug-down is generated. <P>SOLUTION: The construction machine has the speed sensing control means for determining a target value T of a maximum pump torque based on a speed sensing torque ΔT corresponding to rotation speed deviation ΔN between the target rotation speed Nr and real rotation speed Ne of an engine 1, and a pump torque suppressing means for suppressing and controlling a torque adjusting means for a prescribed waiting time C1 so as to set the maximum pump torque T smaller than the target value T from a time point when the current speed sensing torque ΔT becomes larger than a previous speed sensing torque ΔTprv when an operation device 5 is operated from a non-operating state and the engine lug-down is generated when the engine rotation speed is kept at the target rotation speed Nr. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is provided in a construction machine having speed sensing control means such as a hydraulic excavator, and when the engine is driven at a target rotational speed, the engine rotational speed that is generated momentarily when the operating device is operated from a non-operating state. The present invention relates to an engine lug-down suppressing device for a construction machine that suppresses engine lug-down, which is a drop of the engine.
[0002]
[Prior art]
Conventionally, in a construction machine such as a hydraulic excavator, a torque correction value corresponding to a rotational speed deviation between the target rotational speed and the actual rotational speed of the engine, that is, a speed sensing torque is obtained, and a preset maximum pump torque diagram Is provided with speed sensing control means for adding the above-mentioned speed sensing torque to the drive control torque included in the motor to obtain a target value of the maximum pump torque (see, for example, Patent Document 1).
[0003]
In a construction machine equipped with such speed sensing control means, as in a construction machine not equipped with speed sensing control means, the hydraulic actuator is operated while the engine is driven at the target rotational speed. It is known that when the operating device is once returned to neutral and then operated again, an engine lag down, which is a momentary drop in engine speed, occurs.
[0004]
At this time, the maximum pump torque that can be delivered by the main pump that supplies the hydraulic oil to the hydraulic actuator is controlled by the speed sensing control means in accordance with the drop in the engine speed.
[0005]
[Patent Document 1]
JP 2001-140806 A
[0006]
[Problems to be solved by the invention]
As described above, in the prior art provided with the speed sensing control means, when the engine lag down occurs, the speed sensing control means controls the maximum pump torque so as not to exceed the engine torque. With the recovery of the lag down, it takes a short time, for example, about 1 to 2 seconds, until the engine speed returns to the target speed. As a result, it takes time corresponding to the return time of the engine speed described above until the maximum pump torque is restored to the maximum pump torque that can be originally generated. That is, in the prior art, when the engine lag down occurs, the maximum pump torque that the main pump can generate tends to be temporarily reduced according to the time until the engine speed returns to the target speed. There is a problem in that the efficiency of work performed through the hydraulic actuator is reduced.
[0007]
The present invention has been made from the actual situation in the prior art as described above, and an object thereof is to provide speed sensing control means, and to set the engine speed to the target speed when the engine lag down occurs. An object of the present invention is to provide an engine lag down suppression device for a construction machine that can speed up the return.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is driven by an engine, a main pump driven by the engine, torque adjusting means for adjusting the maximum pump torque of the main pump, and pressure oil discharged from the main pump. A hydraulic actuator that operates, an operating device that operates the hydraulic actuator, a torque correction value that is obtained according to a rotational speed deviation between the target rotational speed and the actual rotational speed of the engine, and the torque adjusting means that is based on the torque correction value And a speed sensing control means for determining a target value of the maximum pump torque controlled by the engine, when the engine speed is maintained at the target speed, the non-operating state of the operating device When the engine lag down, which is a drop in the engine speed, is caused by the operation of Among the positive values, the current torque correction value becomes a maximum pump torque smaller than the target value of the maximum pump torque determined by the speed sensing control means after the current torque correction value becomes larger than the previous torque correction value. The torque adjusting means includes pump torque suppressing means for suppressing and controlling the torque adjusting means for a predetermined waiting time.
[0009]
According to the present invention configured as described above, when the engine speed is maintained at the target speed and the engine lag down occurs due to the operation of the operating device from the non-operating state, the pump torque is suppressed. Means implement suppression control. That is, the speed sensing control means from the time when the current torque correction value of the torque sensing value of the speed sensing control means becomes larger than the previous torque correction value after the current torque correction value becomes larger than the previous torque correction value, for example. A process of suppressing and controlling the adjustment of the maximum pump torque by the torque adjusting means for a predetermined waiting time is performed so that the maximum pump torque is smaller than the original target value of the maximum pump torque determined by the above.
[0010]
By the time the predetermined waiting time has passed, the engine speed returns to the target speed. When returning the engine speed to the target speed, it depends on the small maximum pump torque described above, so that the load on the engine is reduced for a predetermined waiting time. For this reason, the engine speed returns to the target speed. Time is getting faster. That is, it is possible to shorten the engine speed recovery time required from the occurrence of engine lag down to the return of the engine speed to the target engine speed.
[0011]
As described above, when the engine speed returns to the target speed and a predetermined waiting time elapses, the speed sensing control means immediately performs processing to obtain the maximum pump torque target value that can be originally obtained. . Therefore, the time from when the engine lag down occurs until the main pump can return to the maximum pump torque that can be originally generated can be shortened.
[0012]
According to the present invention, in the above invention, the pump torque suppressing means comprises means for maintaining the previous maximum pump torque corresponding to the previous torque correction value for the predetermined waiting time.
[0013]
In the present invention configured as above, when the engine lag down occurs and the current torque correction value becomes larger than the previous torque correction value, the previous maximum pump torque is maintained for a predetermined waiting time by the pump torque suppression means. Immediately after the elapse of the predetermined waiting time, the speed sensing control means determines the target value of the maximum pump torque that the main pump can originally output.
[0014]
Further, the present invention is the above invention, wherein the pump torque suppressing means is configured to gradually increase the maximum pump torque over time during the predetermined waiting time with the previous maximum pump torque corresponding to the previous torque correction value as a reference value. It is characterized by comprising means for increasing the torque from the reference value.
[0015]
In the present invention configured as described above, when an engine lag down occurs and the current torque correction value becomes larger than the previous torque correction value, the pump torque suppression means uses the previous maximum pump torque as a reference value to determine a predetermined value. During the waiting time, the maximum pump torque is gradually increased from the reference value as time elapses. Immediately after the predetermined waiting time has elapsed, the target value of the maximum pump torque that the main pump can originally produce by the speed sensing control means The decision is made.
[0016]
The present invention is characterized in that, in the above invention, the predetermined waiting time comprises a variable time according to the torque correction value.
[0017]
In the present invention configured as described above, since the torque correction value corresponds to the engine speed deviation and the engine speed deviation corresponds to the engine load, the torque corresponding to the engine load is small. An appropriate waiting time can be changed according to the correction value. Thereby, the return accuracy of the engine speed to the target speed can be increased.
[0018]
Further, the present invention is characterized in that in the above invention, there is provided means for invalidating the suppression control by the pump torque suppression means when the current torque correction value is larger than a predetermined threshold value.
[0019]
In the present invention configured as described above, for example, when a predetermined threshold value is set to a value slightly smaller than a torque correction value assumed at the time of a half operation performed by the operation device, an engine lag down is caused by the half operation. In this case, even when the current torque correction value becomes larger than the previous torque correction value, the current torque correction value is kept larger than a predetermined threshold value. Accordingly, at this time, the suppression control by the pump torque suppression means is invalidated, and the target value of the maximum pump torque by the speed sensing control means is determined.
[0020]
For example, when an engine lag down occurs due to a sudden operation or heavy load of the operating device, when the current torque correction value becomes larger than the previous torque correction value, the current torque correction value is Since it becomes smaller than the predetermined threshold value, the suppression control of the maximum pump torque by the pump torque suppression means is performed.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of an engine lug-down suppressing device for a construction machine according to the present invention will be described with reference to the drawings.
[0022]
FIG. 1 is a diagram showing a main configuration of a construction machine provided with the engine lug-down suppressing device of the present invention.
[0023]
A first embodiment of an engine lug-down suppressing device according to the present invention is provided in a construction machine such as a hydraulic excavator. This hydraulic excavator is configured as a main part, as shown in FIG. For example, a variable displacement hydraulic pump driven by the motor, that is, a main pump 2, a pilot pump 3, and a tank 4 are provided.
[0024]
Further, a hydraulic actuator (not shown) such as a boom cylinder and an arm cylinder driven by pressure oil discharged from the main pump 2, an operating device 5 for operating the hydraulic actuator, and a tilt for controlling a tilt angle of the main pump 2. A control actuator 6 and torque adjusting means for adjusting the maximum pump torque T of the main pump 2 are provided.
[0025]
This torque adjusting means corresponds to the torque control valve 7 that controls the tilt control actuator 6 so as to keep the maximum pump torque T constant regardless of the change in the discharge pressure of the main pump 2 and the operation amount of the operating device 5. And a position control valve 8 for adjusting the maximum pump torque T.
[0026]
Further, the tilt sensor 9 that detects the tilt angle of the main pump 2, the discharge pressure detecting means that detects the discharge pressure of the main pump 2, that is, the discharge pressure sensor 10, and the operation device 5 are output. A pilot pressure detecting means for detecting the pilot pressure, that is, a pilot pressure sensor 11 and a rotation speed indicator 12 for instructing a target rotation speed of the engine 1 are provided.
[0027]
In addition, the vehicle body control that inputs signals from the sensors 9 to 11 and the rotation speed indicator 12 and has a storage function and a calculation function including a logical judgment, and outputs a control signal according to the calculation result. A controller 13 and an engine controller 15 that outputs a signal for controlling the fuel injection pump 14 of the engine 1 in accordance with a control signal output from the vehicle body controller 13 are provided. The fuel injection pump 14 is also provided with a rotation sensor 1 a that detects the actual rotation speed of the engine 1 and outputs the detected rotation speed to the engine controller 15.
[0028]
In addition, an electromagnetic valve 16 is provided which operates according to a control signal output from the vehicle body controller 13 and operates the spool 7a of the torque control valve 7 against the force of the spring 7b.
[0029]
2 to 5 are diagrams showing basic characteristics possessed by the construction machine shown in FIG. 1, that is, a hydraulic excavator. FIG. 2 is a pump discharge pressure-push-off volume characteristic (corresponding to PQ characteristics), and pump discharge pressure-pump. FIG. 3 is a diagram showing torque characteristics, FIG. 3 is a diagram showing PQ diagram movement characteristics, FIG. 4 is a diagram showing target rotational speed-torque characteristics, and FIG. 5 is a diagram showing position control characteristics.
[0030]
As a basic characteristic of this hydraulic excavator, the relationship between the pump discharge pressure P and the displacement volume q shown in FIG. 2A, that is, the relationship between the pump discharge pressure P and the displacement flow rate Q corresponding to the displacement volume q. It has the characteristics shown in a certain PQ diagram 20. This PQ diagram 20 corresponds to the constant pump torque diagram 21. Further, as shown in FIG. 2B, the pump torque has a characteristic shown by a pump torque diagram 22 by PQ control which is a relationship of pump discharge pressure P-pump torque.
[0031]
As described above, if the discharge pressure of the main pump 2 is P, the displacement volume is q, the pump torque is Tp, and the mechanical efficiency is ηm,
Tp = (P × q) / (628 × ηm) (1)
It is known that
[0032]
Further, as a basic characteristic of the hydraulic excavator, as shown in FIG. 3, it has a PQ diagram moving characteristic. In FIG. 3, 23 is a PQ diagram corresponding to the maximum pump torque T based on the target rotational speed of the engine 1, and 24 is a PQ diagram corresponding to a low torque lower than the maximum pump torque described above.
[0033]
Further, as basic characteristics of the hydraulic excavator, the characteristics shown in the engine maximum torque diagram 25 shown in the relationship of the target rotational speed-torque of the engine 1 shown in FIG. 4 and the engine maximum torque diagram 25 are not exceeded. The maximum pump torque curve to be suppressed has the characteristics shown in FIG. The maximum pump torque T becomes the minimum value Tp1 on the maximum pump torque diagram 26 when the target rotational speed of the engine 1 is relatively small, and the rotational speed of the engine 1 becomes the target rotational speed n2 corresponding to the rated rotational speed. Then, the maximum value Tp2 on the maximum pump torque diagram 26 is obtained.
[0034]
The PQ diagram when the maximum value Tp2 is reached on the maximum pump torque diagram 26 shown in FIG. 4 becomes the PQ diagram 23 of FIG. 3, and becomes the minimum value Tp1 on the maximum pump torque diagram 26 shown in FIG. The PQ diagram at that time is, for example, as shown in the PQ diagram 24 of FIG.
[0035]
In addition, as shown in FIG. 5, the hydraulic excavator has a position control characteristic based on the operation of the position control valve 8 accompanying the operation of the operating device 5 as shown in FIG. 5. FIG. 5 shows a position control diagram 27 when the discharge pressure P of the main pump 2 is P1.
[0036]
As shown in FIG. 1, since the position control valve 8 and the torque control valve 7 are connected in tandem, in this excavator, when the pump discharge pressure P is P1, the PQ diagram of FIG. The maximum pump torque is controlled according to the minimum value of 20 and the position control diagram 27.
[0037]
FIG. 6 is a diagram showing engine control characteristics possessed by the construction machine shown in FIG. 1, that is, a hydraulic excavator, and FIG. 7 is a diagram showing pilot pressure-displacement volume characteristics stored in the vehicle body controller.
[0038]
As shown in FIG. 6, this hydraulic excavator has an isochronous characteristic realized by, for example, electronic governor control as an engine control characteristic.
[0039]
Further, as shown in FIG. 7, the vehicle body controller 13 stores the relationship between the pilot pressure Pi corresponding to the operation amount of the operating device 5 and the displacement volume q of the main pump 2. As the pilot pressure Pi increases, the displacement q of the main pump 2 gradually increases.
[0040]
Further, the vehicle body controller 13 obtains a torque correction value, that is, a speed sensing torque ΔT according to the revolution speed deviation ΔN between the target revolution speed Nr and the actual revolution speed Ne of the engine 1, and based on the speed sensing torque ΔT, A speed sensing control means for determining a target value T of the maximum pump torque adjusted by a torque adjusting means constituted by the torque control valve 7 and the position control valve 8 is provided.
[0041]
FIG. 8 is a block diagram showing speed sensing control means included in the vehicle body controller.
[0042]
As shown in FIG. 8, the speed sensing control means includes a subtractor 40 for obtaining a rotational speed deviation ΔN between the target rotational speed Nr and the actual rotational speed Ne of the engine 1, and the maximum pump torque diagram shown in FIG. That is, the current speed corresponding to the rotation speed deviation ΔN output from the horsepower control torque calculation unit 41 in which the maximum pump torque diagram that is the relationship between the target rotation number Nr and the drive control torque Tb is set, and the subtraction unit 40. The correction torque calculation unit 42 for obtaining the sensing torque ΔT, and the addition unit for adding the horsepower control torque Tb output from the horsepower control torque calculation unit 41 and the current speed sensing torque ΔT output from the correction torque calculation unit 42 43, and the target value T of the maximum pump torque obtained by the adding unit 43 is output to the control unit of the electromagnetic valve 16 shown in FIG.
[0043]
In particular, in the first embodiment, when the vehicle body controller 13 holds the engine 1 at the target rotational speed Nr, the engine rotational speed is accompanied by the operation from the non-operating state of the operating device 5 shown in FIG. When the engine lag down, which is a drop in the engine speed, occurs, the speed sensing torque ΔT of the speed sensing torque described above becomes greater than the speed sensing torque ΔTprv determined last time. From the point of time when the torque adjustment means becomes larger than the target value T of the maximum pump torque determined by the speed sensing torque control means, the torque adjusting means is set to a predetermined waiting time C1. Pump torque suppression means for suppressing control is provided.
[0044]
This pump torque suppression means is included in the processing procedure shown in the flowchart of FIG. 9 executed by the vehicle body controller 13 described later. For example, the previous pump torque suppression T corresponding to the previous speed sensing torque ΔTprv is obtained. It comprises means for maintaining the predetermined waiting time C1 described above.
[0045]
The predetermined waiting time C1 is set in consideration of the model of the engine 1. Further, for example, in a state where the engine 1 is held at the rated rotational speed that is the target rotational speed Nr, the engine 1 is returned to the target rotational speed Nr when the operating device 5 is operated from non-operation to the maximum load. It is set in consideration of time. For example, C1 = 1.2 seconds is set.
[0046]
Hereinafter, the operation of the first embodiment will be described with reference to the flowchart shown in FIG. Further, the description will be given with reference to FIG. FIG. 10 is a diagram showing a time-engine speed characteristic and a time-maximum pump torque characteristic obtained in the first embodiment.
[0047]
The vehicle body controller 13 first calculates the target rotational speed Nr of the engine 1 based on the signal input from the target rotational speed indicator 12 as shown in step S1 of FIG. Further, as shown in step S2, the calculation for obtaining the actual rotational speed Ne of the engine 1 is performed based on the signal input from the rotation sensor 1a via the engine controller 15. Further, as shown in step S3, the drive control torque calculator 41 of the speed sensing control means performs a calculation for obtaining the horsepower control torque Tb corresponding to the target rotational speed Nr of the engine 1. Further, as shown in step S4, the subtraction unit 40 of the speed sensing control means obtains the rotational speed deviation ΔN between the target rotational speed Nr and the actual rotational speed Ne, and calculates the correction torque of the speed sensing control means. The unit 42 performs an operation for obtaining the current speed sensing torque ΔT according to the rotational speed deviation ΔN.
[0048]
Next, as shown in step S5, it is determined whether or not the current speed sensing torque ΔT is equal to or greater than the previous speed sensing torque ΔTprv and the counter is greater than zero.
[0049]
In this case, immediately after the operation of the controller device 5 is started, an engine lag down occurs and the rotation speed of the engine 1 starts to decrease from the operation start point 50 in FIG. Accordingly, the current speed sensing torque ΔT becomes smaller than the previous speed sensing torque ΔTprv, and is obtained by the adding unit 43 of the speed sensing control means as shown by an arrow 57 in FIG. The target value T of the maximum pump torque starts to decrease.
[0050]
Incidentally, 51 in FIG. 10 (a) is a time-engine speed obtained in a construction machine having a conventional speed sensing control means that is not provided with the pump suppression means that is a feature of the first embodiment. The characteristic is shown, 52 has shown the time-engine speed characteristic in this 1st Embodiment. Further, 55 in FIG. 10B is the time-maximum obtained in the construction machine having the conventional speed sensing control means that is not provided with the pump torque suppression means that is the feature of the first embodiment. A pump torque characteristic is shown, and 56 shows a time-maximum pump torque characteristic in the first embodiment.
[0051]
Therefore, immediately after the operation of the controller device 5 is started, the current speed sensing torque ΔT is smaller than the previous speed sensing torque ΔTprv as described above, and the determination in step S5 shown in FIG. Move on.
[0052]
In step S6, a process of setting a predetermined waiting time C1 (= 1.2 seconds) in the counter is performed, and the process proceeds to step S7.
[0053]
In step S7, a process of replacing the previous speed sensing torque ΔTprv with the speed sensing torque ΔT obtained this time is performed, and the process proceeds to step S8.
[0054]
In step S8, the addition unit 43 of the speed sensing control means performs an operation for adding the speed sensing torque ΔT obtained this time to the horsepower control torque Tb obtained in step S3 to obtain the target value T of the maximum pump torque. Then, the process proceeds to step S9.
[0055]
In step S9, a process of outputting a control signal corresponding to the target value T of the maximum pump torque obtained in step S8 to the control unit of the electromagnetic valve 16 shown in FIG.
[0056]
That is, the process following the above-described steps S5-S6-S7-S8-S9 is a process based on the speed sensing control means as in the conventional construction machine equipped with the speed sensing control means.
[0057]
In the tilt control actuator 6 shown in FIG. 1, the force of the pressure oil supplied to the pressure receiving chamber 6a via the torque control valve 7 and the position control valve 8 is based on the pilot pressure supplied to the pressure receiving chamber 6b. When the force is larger than the force, the spool 6c moves to the right in FIG. 1, and the tilt angle of the main pump 2 decreases as indicated by the arrow 30. Conversely, when the force due to the pressure in the pressure receiving chamber 6b is greater than the force due to the pressure in the pressure receiving chamber 6a, the spool 6c moves to the left in FIG. 1 and the tilt angle of the main pump 2 as shown by the arrow 31. Will increase.
[0058]
Further, the torque control valve 7 is configured such that, for example, the resultant force of the force due to the discharge pressure P of the main pump 2 applied to the pressure receiving chamber 7d and the force due to the pilot pressure applied to the pressure receiving chamber 7c via the electromagnetic valve 16 is the force of the spring 7b. If it becomes larger, the spool 7a moves to the left in FIG. 1 and tends to supply pressure oil to the pressure receiving chamber 6a of the tilt control actuator 6, that is, to tend to decrease the tilt angle of the main pump 2. Conversely, when the resultant force of the force due to the pressure applied to the pressure receiving chamber 7d and the force due to the pressure applied to the pressure receiving chamber 7c is smaller than the force of the spring 7b, the spool 7a moves to the right in FIG. There is a tendency to return the pressure oil in the pressure receiving chamber 6a of the tilt control actuator 6 to the tank 4, that is, a tendency to increase the tilt angle of the main pump 2.
[0059]
Further, as the value of the control signal output from the vehicle body controller 13 increases, the electromagnetic valve 16 tends to be switched to the lower position side in FIG. 1 against the force of the spring 16a, and the pressure receiving chamber of the torque control valve 7 is increased. 7c tends to return oil to the tank 4 via the electromagnetic valve 16. Therefore, in such a case, the inclination angle of the main pump 2 tends to increase. That is, in the torque control valve 7, the spool 7a moves depending on the magnitude relationship between the force of the pressure receiving chamber 7d and the pressure of the pressure receiving chamber 7c and the force of the spring 7b.
[0060]
Further, the position control valve 8 causes the spool 8b to move to the right in FIG. 1 when the force by the pilot pressure pi guided through the pilot conduit 32 in accordance with the operation of the operation device 5 becomes larger than the force of the spring 8a. The pressure oil in the pressure receiving chamber 6a of the tilt control actuator 6 tends to return to the tank 4, that is, the tilt angle of the main pump 2 tends to increase. On the contrary, when the force by the pilot pressure guided through the pilot pipe line 32 becomes smaller than the force of the spring 8 a, the spool 8 b moves to the left in FIG. 1 and enters the pressure receiving chamber 6 a of the tilt control actuator 6. The pressure oil from the pilot pump 3 tends to be supplied, that is, the tilt angle of the main pump 2 tends to decrease.
[0061]
By the operation of the torque adjusting means including the torque control valve 7 and the position control valve 8, the tilt angle corresponding to the discharge pressure P of the main pump 2, that is, the displacement volume q is controlled. The maximum pump torque T of the main pump 2 is adjusted so that the maximum pump torque T = Tp obtained by
[0062]
Further, during the process of steps S5-S6-S7-S8-S9 in FIG. 9 described above, the engine speed at the time of engine lug down shown in FIG. When the maximum pump torque T shown in FIG. 10B becomes the smallest, there is a situation where the current speed sensing torque ΔT becomes equal to or higher than the previous speed sensing torque ΔTprv. At this time, the counter is already set to a predetermined waiting time C1 (= 1.2 seconds) in step S6.
[0063]
Therefore, the determination in step S5 of FIG. 9 is satisfied, that is, it is determined that the current speed sensing torque ΔT is equal to or greater than the previous speed sensing torque ΔTprv, and the counter value is determined to be greater than 0, and the process proceeds to step S10.
[0064]
In this procedure S10, the measurement of the waiting time C1 is started, and the procedure proceeds to procedure S11.
[0065]
In step S11, the previous speed sensing torque ΔTprv is added to the horsepower control torque Tb obtained in step S3 to calculate the previous maximum pump torque T indicated by reference numeral 59 in FIG. 10B. Then, the process proceeds to step S9.
[0066]
In step S9, a process of outputting a control signal corresponding to the previous maximum pump torque T obtained in step S11 to the control unit of the electromagnetic valve 16 shown in FIG. 1 is performed.
[0067]
The processing subsequent to steps S5-S10-S11-S9 in FIG. 9 is the content of the suppression control of the pump torque suppression means characterized in the first embodiment, and a predetermined waiting time C1 (= 1.2 seconds). This process is continued during That is, the suppression control of the torque adjusting means including the torque control valve 7 and the position control valve 8 by the pump torque suppressing means is performed.
[0068]
During the suppression control of the torque adjusting means by the pump torque suppressing means, that is, during the predetermined waiting time C1 (= 1.2 seconds), the maximum pump torque T is the same as that in the construction machine having the conventional speed sensing control means. For example, control is performed so that the previous maximum pump torque T indicated by reference numeral 59 is maintained so as to be smaller than the maximum pump torque T. In the control by the conventional speed sensing control means, as shown by the arrow 58 in FIG. 10 (b), there is a tendency to gradually increase from the smallest previous maximum pump torque T.
[0069]
Since the load applied to the engine 1 is reduced during the waiting time C1 (= 1.2 seconds), the rotational speed of the engine 1 is quickly set to the target as shown by the return time point 53 in FIG. Return to the rotational speed Nr.
[0070]
Immediately after the elapse of the predetermined waiting time C1 (= 1.2 seconds), the maximum pump torque returns to the original maximum pump torque as shown in FIG. 10B.
[0071]
As shown in FIG. 10 (a), when the engine lag down occurs, in the first embodiment, the engine speed is increased by the time t1 as compared with the construction machine having the conventional simple speed sensing control means. The target rotational speed Nr can be quickly restored. Accordingly, as shown in FIG. 10B, the maximum pump torque T can also be returned earlier by time t1a than the conventional construction machine.
[0072]
In the first embodiment, as shown in FIG. 10A, a minute engine lag down occurs after the engine speed is returned to the target speed Nr as indicated by the return time point 53. Such a decrease in engine speed is negligible in practice. Similarly, as shown in FIG. 10B, a slight decrease in the maximum pump torque T that occurs after the maximum pump torque T returns to the original maximum pump torque T can be ignored in practice.
[0073]
As described above, after the predetermined waiting time C1 (= 1.2 seconds) has elapsed, the target value T of the maximum pump torque is determined by the speed sensing control means, and the torque adjusting means is maximized according to the target value T. Adjust the pump torque T.
[0074]
As described above, according to the first embodiment, the pump torque suppressing means maintains the previous maximum pump torque 59 in FIG. 10B for the predetermined waiting time C1 (= 1.2 seconds). The engine speed can be quickly returned to the target speed Nr when the engine lag is down, and the maximum pump torque T can be returned to the maximum pump torque T that can be originally generated. it can. Therefore, it is possible to suppress a reduction in work efficiency during the engine lug down in a short time.
[0075]
FIG. 11 is a diagram showing time-engine speed characteristics and time-maximum pump torque characteristics obtained in the second embodiment of the present invention.
[0076]
In FIG. 11 (a), 50 is the time when the engine lag down occurs, that is, the operation start time of the operating device 5, 51 is the time-engine speed characteristic in the construction machine provided with the conventional speed sensing control means. , 60 is the time-engine speed characteristic of the second embodiment, 54 is the previous return point when the engine speed returns to the target speed Nr, and 61 is the first time when the engine speed returns to the target speed Nr. This is the return time of the second embodiment.
[0077]
Further, 59 shown in FIG. 11 (b) is the smallest maximum pump torque T, that is, the previous maximum pump torque T constituting a reference value described later, 55 is the previous time-maximum pump torque characteristic, and 62 is It is a time-maximum pump torque characteristic of this 2nd Embodiment.
[0078]
In this second embodiment, the pump torque suppression means uses the previous maximum pump torque 59 as a reference value, and gradually references the maximum pump torque T as time passes during a predetermined waiting time C1 (= 1.2 seconds). Consists of means to increase from the value.
[0079]
The time-maximum pump torque characteristic 62 of the second embodiment shown in FIG. 11 (b) shows that the current speed sensing torque ΔT is equal to or higher than the previous speed sensing torque ΔTprv as determined in step S5 of FIG. It can be realized by, for example, a configuration in which the value of ΔTprv is gradually increased as time elapses in the calculation for obtaining the maximum pump torque T by adding the previous speed sensing torque ΔTprv to the drive control torque Tb in step S11. Other configurations are the same as those of the first embodiment described above.
[0080]
In the second embodiment configured as described above, during the predetermined waiting time C1 (= 1.2 seconds), as shown in FIG. 11B, the maximum pump torque T by the conventional speed sensing control means is used. Since the maximum pump torque T is suppressed to a small value, the load on the engine 1 is reduced during this period, and the engine speed returns to the target speed Nr as indicated by the return time 61 in FIG. The time can be advanced by time t2 compared to the previous time. Along with this, the time for returning to the original maximum pump torque T at the time of occurrence of the engine lag down can also be advanced by the time t2a compared to the conventional time.
[0081]
Therefore, similarly to the first embodiment described above, it is possible to suppress a reduction in work efficiency when engine lag down occurs in a short time.
[0082]
12 is a flowchart showing a processing procedure in the vehicle body controller included in the third embodiment of the present invention, FIG. 13 is a diagram showing setting means provided in the vehicle body controller included in the third embodiment of the present invention, and FIG. These are figures which show the time-engine speed characteristic obtained by 3rd Embodiment, and the time-maximum pump torque characteristic.
[0083]
Of the processing procedures in the flowchart shown in FIG. 12, the processing procedure different from the flowchart shown in FIG. 9 according to the first embodiment described above is only procedure S12. Other processing procedures are the same as those shown in FIG.
[0084]
Further, the setting means shown in FIG. 13 is set to have a relationship that makes the waiting time C1 variable according to the value of the current speed sensing torque ΔT obtained in step S4 of FIG. When the engine load when operating the operating device 5 is large, the value of the speed sensing torque ΔT required this time is small, so a relatively long waiting time C1 is selected. Further, when the engine load when operating the operation device 5 is small, the value of the speed sensing torque ΔT required this time is relatively large, so that a short waiting time C1 is selected.
[0085]
That is, in the third embodiment, the predetermined waiting time C1 when the torque adjusting means is restrained and controlled by the pump torque restraining means is a variable time corresponding to the value of the speed sensing torque ΔT. Other configurations are the same as those of the first embodiment described above.
[0086]
Note that 50 shown in FIG. 14 (a) is 50 when engine lag down occurs, that is, when the operation device 5 starts to operate, and 70 is time-engine rotation in a construction machine provided with a conventional speed sensing control means. Number characteristic, 71 is the time-engine speed characteristic of the third embodiment, 73 is a previous return point when the engine speed returns to the target speed Nr, 72 is the engine speed at the target speed Nr This is the return time of the third embodiment to return.
[0087]
Also, 76 shown in FIG. 14B is the smallest maximum pump torque T, that is, when the current speed sensing torque ΔT is determined to be greater than or equal to the previous speed sensing torque ΔTprv in the judgment of step S45 shown in FIG. The previous maximum pump torque T is shown. Reference numeral 74 denotes a conventional time-maximum pump torque characteristic, and reference numeral 75 denotes a time-maximum pump torque characteristic of the third embodiment.
[0088]
As described above, the third embodiment differs from the first embodiment in the process of step S12 shown in FIG. 12, and if the current speed sensing torque ΔT is smaller than the previous speed sensing torque ΔTprv in step S5. When it is determined, the process of step S12 is executed.
[0089]
The process of step S12 is a process for obtaining a predetermined waiting time C1 according to the obtained speed sensing torque ΔT, and the waiting time C1 is selected from the setting means of FIG. Immediately after the engine load at the time of the engine lag down is relatively small and the waiting time C1 is selected as 0.6 seconds, the engine speed shown in FIG. 14 and the maximum pump torque T shown in FIG. 14 (b) is the smallest, the speed sensing torque ΔT of this time is determined to be the previous speed sensing torque according to the judgment in step S5 of FIG. It is determined whether or not ΔTprv or more and the counter value (C1) is greater than 0, the process is processed as steps S5-S10-S11-S9 in FIG. 12, and as shown in FIG. 14B. In addition, during the waiting time C1 (= 0.6 seconds), the suppression control of the torque adjusting unit by the pump suppression unit described above is performed.
[0090]
As a result, as shown in FIG. 14 (a), the return to the target rotational speed Nr is time t3 earlier than before, and the return to the maximum pump torque that can be originally produced is accordingly higher than before. Time t3a is earlier.
[0091]
In the third embodiment configured as described above, the waiting time C1 can be changed to an appropriate time according to the magnitude of the engine load when the engine lag down occurs, so that the engine speed can be changed to the target speed Nr. The return accuracy can be increased, which further contributes to the suppression of work efficiency reduction when such an engine lag down occurs.
[0092]
FIG. 15 is a flowchart showing a processing procedure in the vehicle body controller included in the fourth embodiment of the present invention.
[0093]
Of the processing procedures in the flowchart shown in FIG. 15 according to the fourth embodiment, only the steps S13 and S14 differ from the flowchart shown in FIG. 9 according to the first embodiment described above.
[0094]
In the fourth embodiment, a predetermined threshold value ΔTa is set in the correction torque calculation unit 42 of the speed sensing control means shown in FIG. 8 described above, and the current torque correction value, that is, the speed sensing torque ΔT is set to a predetermined value. When larger than the threshold value ΔTa, there is provided means for invalidating the suppression control of the torque adjusting means by the pump torque suppressing means described above. The processing subsequent to steps S13-S14-S7-S8-S9 in FIG. 15 is the contents of the means for invalidating the suppression control by the pump torque suppression means described above.
[0095]
The predetermined threshold value ΔTa is set to a value slightly smaller than the speed sensing torque ΔT assumed at the time of a half operation performed by the operation device 5, for example. Other configurations are the same as those in the first embodiment described above.
[0096]
In the fourth embodiment configured as described above, for example, when the engine 1 is held at the target rotational speed Nr, the non-operating operation device 5 is half-operated, and engine half-down occurs due to this half-operation. Since the speed sensing torque ΔT obtained in step S4 in FIG. 15 does not become smaller than the predetermined threshold value ΔTa, the steps S5-S13-S14-S7-S8-S9 are processed, and the conventional speed sensing control means is used. A target value T of the maximum pump torque is obtained, and the torque adjusting means including the torque control valve 7 and the position control valve 8 is suppressed and controlled by this target value T.
[0097]
Therefore, when such an engine lag down occurs, the time for the engine speed to return to the target speed Nr is equivalent to that in a construction machine having a conventional speed sensing control means. In general, the engine load during the half operation is small, and therefore the scale of the engine lug down is small, so that the engine speed can be returned to the target speed Nr relatively quickly, and accordingly, the maximum that the main pump 2 can originally output. The return to the pump torque T is quick. From such a situation, during this half operation, it is possible to ignore the decrease in work efficiency when the engine speed returns to the target speed Nr.
[0098]
For example, when the operating device 5 is suddenly operated and an engine lag down occurs due to a heavy load on the engine 1, the current speed sensing torque ΔT obtained in step S4 in FIG. It becomes smaller than the threshold value ΔTa, the determination in step S13 of FIG. 15 is Yes, and a predetermined waiting time C1 is set in step S6. Accordingly, when the current speed sensing torque ΔT becomes equal to or higher than the previous speed sensing torque ΔTprv, the value (C1) of the counter is larger than 0, and therefore, the processing subsequent to steps S5-S10-S11-S9 is performed. As described in the first embodiment, the suppression control of the torque adjusting means by the pump torque suppressing means is performed. This processing operation is equivalent to that in the first embodiment described above.
[0099]
As described above, in the fourth embodiment, when engine lag down occurs, if it takes time to return the engine speed to the target speed Nr, torque adjusting means by the pump torque suppressing means. However, if the return of the engine speed to the target speed Nr is considered to be a short time, the suppression control by the pump torque suppression means is invalidated. The fourth embodiment configured in this way is also basically capable of performing the suppression control of the torque adjusting means by the pump torque suppressing means, and is equivalent to the operational effects obtained in the first embodiment described above. An effect can be obtained.
[0100]
【The invention's effect】
As described above, according to the present invention, there is provided the speed sensing control means, and it is possible to speed up the return of the engine speed to the target speed when the engine lag down occurs. When the engine lag down occurs, the time required for the main pump to return to the maximum pump torque that can be originally produced can be shortened, and a reduction in work efficiency when the engine lag down occurs can be suppressed as compared with the conventional case.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a main part of a construction machine provided with an engine lug-down suppressing device of the present invention.
FIG. 2 is a diagram showing a pump discharge pressure-push-off volume characteristic (corresponding to a PQ characteristic) and a pump discharge pressure-pump torque characteristic among the basic characteristics possessed by the construction machine shown in FIG.
FIG. 3 is a diagram showing a PQ diagram movement characteristic among basic characteristics possessed by the construction machine shown in FIG. 1;
4 is a diagram showing a target rotational speed-torque characteristic among basic characteristics possessed by the construction machine shown in FIG. 1; FIG.
FIG. 5 is a diagram showing position control characteristics among basic characteristics possessed by the construction machine shown in FIG. 1;
6 is a diagram showing engine control characteristics possessed by the construction machine shown in FIG. 1; FIG.
FIG. 7 is a diagram showing pilot pressure-push-off volume characteristics stored in a vehicle body controller included in the first embodiment of the engine lag-down suppressing device of the present invention.
FIG. 8 is a block diagram showing speed sensing control means provided in the vehicle body controller included in the first embodiment of the present invention.
FIG. 9 is a flowchart showing a processing procedure in the vehicle body controller included in the first embodiment of the present invention.
FIG. 10 is a diagram showing a time-engine speed characteristic and a time-maximum pump torque characteristic obtained in the first embodiment of the present invention.
FIG. 11 is a diagram showing a time-engine speed characteristic and a time-maximum pump torque characteristic obtained in the second embodiment of the present invention.
FIG. 12 is a flowchart showing a processing procedure in a vehicle body controller included in the third embodiment of the present invention.
FIG. 13 is a diagram showing setting means provided in a vehicle body controller included in a third embodiment of the present invention.
FIG. 14 is a diagram showing time-engine speed characteristics and time-maximum pump torque characteristics obtained in the third embodiment of the present invention.
FIG. 15 is a flowchart showing a processing procedure in the vehicle body controller included in the fourth embodiment of the present invention.
[Explanation of symbols]
1 engine
1a Rotation sensor
2 Main pump
5 Operation device
7 Torque control valve (torque adjustment means)
8 Position control valve (torque adjustment means)
12 Target speed indicator
13 Car body controller (pump torque suppression means)
15 Engine controller
16 Solenoid valve
40 Subtraction part
41 Horsepower control torque calculator
42 Correction torque calculator
43 Adder
50 Operation start time
52 Time-engine speed characteristics of the first embodiment
53 Return point
56 Time-maximum pump torque characteristics of the first embodiment
57 Maximum previous pump torque
60 Time-engine speed characteristics of the second embodiment
61 Return point
62 Time-maximum pump torque characteristics of the second embodiment
71 Time-engine speed characteristics of the third embodiment
72 Return point
75 Maximum pump torque characteristics of the third embodiment
76 Previous maximum pump torque
t1 time
t1a time
t2 hours
t2a time
t3 time
t3a time
Tb Horsepower control torque
C1 waiting time
T Maximum pump torque (target value)
ΔTa Predetermined threshold
ΔTprv Previous speed sensing torque
ΔT Speed sensing torque

Claims (5)

Engine, main pump driven by the engine, torque adjusting means for adjusting the maximum pump torque of the main pump, a hydraulic actuator driven by pressure oil discharged from the main pump, and an operation for operating the hydraulic actuator Equipment,
Speed sensing control that obtains a torque correction value according to a rotational speed deviation between the target rotational speed and the actual rotational speed of the engine and determines a target value of the maximum pump torque controlled by the torque adjusting means based on the torque correction value A construction machine having means,
When the engine speed is maintained at the target speed, the torque correction value when the engine lag down, which is a drop in the engine speed, is caused by the operation of the operating device from the non-operating state. The torque correction value of the current time is larger than the previous torque correction value, and the maximum pump torque is smaller than the target value of the maximum pump torque determined by the speed sensing control means. An engine lag down suppressing device for a construction machine, comprising pump torque suppressing means for suppressing torque control means for a predetermined waiting time. In the invention of claim 1,
The engine lag down suppressing device for a construction machine, wherein the pump torque suppressing means comprises means for maintaining the previous maximum pump torque corresponding to the previous torque correction value for the predetermined waiting time. In the invention of claim 1,
The pump torque suppression means is a means for gradually increasing the maximum pump torque from the reference value as time elapses during the predetermined waiting time with the previous maximum pump torque corresponding to the previous torque correction value as a reference value. An engine lag down suppressing device for construction machinery, comprising: In the invention of claim 1,
The engine lag-down suppressing device for a construction machine, wherein the predetermined waiting time includes a variable time corresponding to the torque correction value. In the invention of claim 1,
An engine lag down suppression device for a construction machine, comprising: means for invalidating suppression control by the pump torque suppression means when the current torque correction value is greater than a predetermined threshold value.

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