Patent Application
20180355583
The present invention relates to a control system for a hydraulic construction machine.
In general, a hydraulic construction machine is equipped with a hydraulic actuator such as a hydraulic cylinder driving a front work device mounted thereon, an operation device operated by the operator, a hydraulic pump adjusting the delivery flow rate in accordance with the operation amount of the operation device, and a control valve driving a built-in directional control valve with an operation pilot pressure in accordance with the operation amount of the operation device to control the flow rate and direction of the hydraulic fluid supplied from a hydraulic pump to the hydraulic actuator.
When the hydraulic construction machine performs an operation such as excavating, there is generated inside the hydraulic actuator driving the front work device a load pressure in accordance with the excavating reaction force (excavating load), and the delivery pressure of the hydraulic pump is a value obtained by adding together this load pressure and the pressure loss of the hydraulic fluid line. In view of this, the hydraulic construction machine adopts a pump horsepower control in which as the delivery pressure of the hydraulic pump increases, the capacity of the hydraulic pump (delivery flow rate) is reduced to lower the horsepower of the hydraulic pump. The pump horsepower control suppresses deterioration in efficiency due, for example, to the application of an excessive load to the engine driving the hydraulic pump, an excessive increase in the delivery pressure of the hydraulic pump, and an increase in leak flow rate.
In connection with this hydraulic construction machine, there exists a construction machine locus control system converging the front device distal end to a target locus via a satisfactory path always matched with the human feeling independently of the operation amount of the operator (see, for example, Patent Document 1). This locus control system computes the position and attitude of the front device based on a signal from an angle sensor, and computes a target speed vector of the front device based on a signal from an operation lever device. The target speed vector is corrected so as to be directed to a point advanced forwards in the excavation progressing direction by a predetermined distance from a point in the target locus that is at a minimum distance from the front device distal end, and there is computed a target pilot pressure for driving a hydraulic control valve in correspondence with the corrected target speed vector. A proportional solenoid valve is controlled so as to generate the computed target pilot pressure.
Further, there exists a work device control system for a construction machine that aims to improve the position follow-up property of a work device operation cylinder and to secure predetermined finish accuracy even if the excavating load increases during a horizontally leveling operation or a slope face forming operation (see, for example, Patent Document 2). This work device control system constitutes a position follow-up feedback control system controlling a pilot pressure by a solenoid proportional valve so as to eliminate an error between the target position and target speed of each cylinder based on a signal from an operation lever and the actual position and speed of each cylinder based on information obtained from an angle sensor, and adjusts to increase the feedback gain and the feed forward gain by a lookup table in accordance with an increase in the cylinder load pressure.
Patent Document 1: JP-1997-291560-A
Patent Document 2: JP-1997-228426-A
The construction machine locus control system disclosed in Patent Document 1 and the work device control system for the construction machine disclosed in Patent Document 2 eventually achieve their respective objects by controlling the operation pilot pressure drive-controlling a control valve constituting a conventional construction machine. Thus, in both examples, in the case where the excavating load increases, the above-mentioned pump horsepower control is exerted to reduce the delivery flow rate of the hydraulic pump, so that there is generated the possibility of a reduction in the drive speed of the hydraulic actuator.
As a result, in the construction machine locus control system disclosed in Patent Document 1, the speed of the hydraulic actuator, in particular, the speed of the arm cylinder mainly receiving the excavating load is lowered, and the speed balance between a plurality of hydraulic actuators (e.g., the arm cylinder, boom cylinder, and bucket cylinder) is deviated from the target value, with the result that there is generated the possibility of the locus being incapable of controlled as intended. For example, in the case where the excavating operation is being conducted through a combined operation of boom raising and arm crowding, when the excavating load, which is mainly applied to the arm, increases, the arm crowding speed is lowered, and the boom raising speed remains as it is, so that the balance in speed between the two is lost, resulting in deterioration in the finish accuracy.
In the work device control system for the construction machine disclosed in Patent Document 2, the position follow-up feedback control gain is adjusted to be increased in accordance with an increase in the cylinder load pressure. However, the delay in the operation of the hydraulic actuator accompanying the reduction in the delivery flow rate of the hydraulic pump is not always taken into consideration. Thus, in the case, in particular, where the operation speed is high, even if the operation pilot pressure is adjusted to be increased with respect to the increasing speed (changing ratio) of the excavating load generated due to a change in the nature of the soil, a reduction in the operation speed of the hydraulic actuator is unavoidable. Thus, there is generated the possibility of predetermined finish accuracy not being attained in the horizontally leveling operation and slop face forming.
The present invention has been made in view of the above problem. It is an object of the present invention to provide a control system for a hydraulic construction machine that helps to attain predetermined finish accuracy even if the excavating load increases during a horizontally leveling operation or a slope face forming operation.
To achieve the above object, there is adopted, for example the construction as set forth in the appended claims. The present application includes a plurality of means for solving the problem, one example of which is a control system for a hydraulic construction machine, including: a hydraulic actuator; a work device including a boom, an arm, and a bucket driven by the hydraulic actuator; a hydraulic pump supplying a hydraulic fluid to the hydraulic actuator; a pump flow rate control section controlling a delivery flow rate of the hydraulic pump; a pump horsepower control section controlling a horsepower of the hydraulic pump; and a target surface distance acquiring section measuring or computing a target surface distance that is a distance between a construction target surface on which the work device works and the work device. The pump flow rate control section is configured to perform control such that as the target surface distance decreases, the delivery flow rate decreases, and the pump horsepower control section is configured to perform control such that as the target surface distance decreases, the horsepower of the hydraulic pump increases.
According to the present invention, correction control is performed on the pump horsepower in accordance with the distance between the work device and the construction target surface, so that in the case where excavating is performed at a position close to the construction target surface, it is possible to attain predetermined finish accuracy even if the excavating load increases.
In the following, a control system for a hydraulic construction machine according to an embodiment of the present invention will be described with reference to the drawings.
The work device 15 is mounted to the front portion of the upper swing structure 10 so as to be capable of turning upwards. The upper swing structure 10 is equipped with a cab, in which there are arranged operation devices such as a traveling right-hand operation lever device 1a, a traveling left-hand operation lever device 1b, and a right-hand operation lever device 1c and a left-hand operation lever device 1d for commanding the operation of the work device 15 and the swinging operation.
The work device 15 is of a multi-joint structure having a boom 11, an arm 12, and a bucket 8. The boom 11 rotates vertically with respect to the upper swing structure 10 through expansion and contraction of a boom cylinder 5. The arm 12 rotates vertically and in the front-rear direction with respect to the boom 11 through expansion and contraction of an arm cylinder 6, and the bucket 8 rotates vertically and in the front-rear direction with respect to the arm 12 through expansion and contraction of a bucket cylinder 7.
Further, in order to calculate the position of the work device 15, there are provided an angle sensor 13a which is provided in the vicinity of the connection portion between the upper swing structure 10 and the boom 11 and which detects the angle of the boom 11 with respect to the horizontal plane, an angle sensor 13b which is provided in the vicinity of the connection portion between the boom 11 and the arm 12 and which detects the angle of the arm 12, and an angle sensor 13c which is provided in the vicinity of the arm 12 and the bucket 8 and which detects the angle of the bucket 8. Angle signals detected by these angle sensors 13a through 13c are inputted to a main controller 100 described below.
A control valve 20 serves to control the flow (flow rate and direction) of a hydraulic fluid supplied from a hydraulic pump device 2 to each of the actuators such as the boom cylinder 5, the arm cylinder 6, the bucket cylinder 7, and the left and right traveling hydraulic motors 3b and 3a.
In
The hydraulic pump device 2 is equipped with a first hydraulic pump 21 and a second hydraulic pump 22. The first hydraulic pump 21 and the second hydraulic pump 22 are driven by an engine 14, and they deliver the hydraulic fluid respectively to a first pump line L1 and a second pump line L2. The first hydraulic pump 21 and the second hydraulic pump 22 are variable displacement hydraulic pumps. They are equipped with a first regulator 27 and a second regulator 28. The regulators 27 and 28 control the tilting position of a swash plate that is a displacement varying mechanism of the first hydraulic pump 21 and the second hydraulic pump 22, controlling the pump delivery flow rate.
The first regulator 27 and the second regulator 28 undergo positive tilting control by a pilot hydraulic fluid supplied thereto via solenoid proportional valves 27a and 28a. Further, the delivery pressure of the first hydraulic pump 21 and the delivery pressure of the second hydraulic pump 22 are respectively fed back to the first regulator 27 and the second regulator 28, and the absorption horsepower of these hydraulic pumps is controlled by these delivery pressures and the pilot hydraulic fluid supplied via the solenoid proportional valves 27b and 28b. This absorption horsepower control is performed to control hydraulic pump tilting such that a load determined by the hydraulic pump delivery pressure and the hydraulic pump tilting does not exceed the engine output power.
The control valve 20 is formed by two pump line systems consisting of a first pump line L1 and a second pump line L2. Connected to the first pump line L1 are a boom 1 directional control valve 23 and an arm 2 directional control valve 26, and the hydraulic fluid delivered from the first hydraulic pump 21 is supplied to the boom cylinder 5 and the arm cylinder 6. Similarly, connected to the second pump line L2 are an arm 1 directional control valve 25 and a boom 2 directional control valve 24, and the hydraulic fluid delivered from the second hydraulic pump 22 is supplied to the arm cylinder 6 and the boom cylinder 5.
The boom 1 directional control valve 23 is driven to operate by the pilot hydraulic fluid supplied to the operation section via solenoid proportional valves 23a and 23b. Similarly, the boom 2 directional control valve 24 is driven to operate by the pilot hydraulic fluid supplied to the operation section thereof via solenoid proportional valves 24a and 24b, the arm 1 directional control valve 25 is driven to operate by the pilot hydraulic fluid applied to the operation section thereof via solenoid proportional valves 25a and 25b, and the arm 2 directional control valve 26 is driven to operate by the pilot hydraulic fluid supplied to the operation section thereof via solenoid proportional valves 26a and 26b.
Using the pilot hydraulic fluid supplied from a pilot hydraulic fluid source 29 as the initial pressure, these solenoid proportional valves 23a through 28b output a secondary pilot hydraulic fluid reduced in pressure in accordance with a command current from the main controller 100 to the directional control valves 23 through 26 and the regulators 27 and 28.
The right-hand operation lever device 1c outputs a voltage signal to the main controller 100 as a boom operation signal or a bucket operation signal in accordance with the operation amount and the operational direction of the operation lever. Similarly, the left-hand operation lever device 1d outputs a voltage signal to the main controller 100 as a swing operation signal or an arm operation signal in accordance with the operation amount and the operational direction of the operation lever.
The main controller 100 inputs a dial signal from an engine control dial 31, a boom operation amount signal transmitted from a right-hand operation lever device 1c, an arm operation amount signal transmitted from the right-hand operation lever device 1c, a mode setting signal transmitted from a mode setting switch 32 as a setting device, a horsepower adjustment signal transmitted from a horsepower adjustment dial 33 as a setting device, a construction target surface position signal transmitted from the information controller 200, and a boom angle signal and an arm angle signal transmitted from angle sensors 13a and 13b serving as position acquiring means, and, in accordance with these input signals, transmits an engine speed command to an engine controller (not shown) controlling the engine 14, and outputs command signals driving the solenoid proportional valves 23a through 28b. The computation performed by the information controller 200 is not directly related to the present invention, so a description thereof will be left out.
The engine control dial 31, the mode setting switch 32, and the horsepower adjustment dial 33 are arranged inside the cab. The mode setting switch 32 makes it possible to make a selection as to which of energy saving property and speed follow-up property a priority is to be given to in the operation of the hydraulic construction machine. For example, selection is possible from among the following: 1: normal mode, 2: horsepower increase mode, 3: locus control mode, and 4: horsepower increase+locus control mode. As described in detail below, the horsepower adjustment dial 33 allows further adjustment of a target horsepower signal computed.
Next, the main controller 100 constituting the control system of the hydraulic construction machine according to an embodiment of the present invention will be described with reference to the drawings.
As shown in
The target engine speed computation section 110 inputs the dial signal from the engine control dial 31, and computes a targets engine speed in accordance with the input signal, outputting the target engine speed to the target speed computation section 120 and the hydraulic control section 130.
The target speed computation section 120 inputs the boom operation amount signal from the right-hand operation lever device 1c, the arm operation amount signal from the left-hand operation lever device 1d, and the target engine speed signal from the target engine speed computation section 110, and computes the boom target speed and the arm target speed in accordance with the input signals, outputting them to the target speed correction section 170. The larger the boom operation amount in the boom raising direction, the higher the boom target speed in the positive direction, and the larger the boom operation amount in the boom lowering direction, the higher the boom target speed in the negative direction. Similarly, the larger the arm operation amount in the arm crowding direction, the higher the arm target speed in the positive direction, and the larger the arm operation amount in the arm dumping direction, the higher the arm target speed in the negative direction.
The work device position acquiring section 140 inputs the boom angle signal and the arm angle signal from the angle sensors 13a and 13b, and computes the distal end position of the bucket 8 by using geometrical information on the boom 11 and the arm 12 previously set in accordance with the input signals, outputting it to the target surface distance acquiring section 150 as a work device position signal. Here, the work device position is computed, for example, as a point in a coordinate system fixed to the hydraulic construction machine. The work device position, however, is not restricted thereto. It may be computed as a plurality of point groups in which the configuration of the work device 15 is taken into consideration. Further, the same computation as that in the construction machine locus control system disclosed in Patent Document 1 may be performed.
The target surface distance acquiring section 150 inputs a construction target surface position signal transmitted from the information controller 200, and a work device position signal from the work device position acquiring section 140, and, based on the input signals, computes the distance between the work device 15 and the construction target surface (hereinafter referred to as the target surface distance), outputting it to the hydraulic control section 130 and the target speed correction section 170. Here, the construction target surface position is given, for example, as two points in a coordinate system fixed to the hydraulic construction machine. The construction target surface position, however, is not restricted thereto. It may also be given as two points in a global coordinate system. In this case, however, it is necessary to effect coordinate conversion to the coordinate system as that of the work device. In the case where the work device position is computed as a point group, the target surface distance may be computed by using the point closest to the construction target surface position. Further, the same computation as that of the minimum distance Δh of the locus control system of the construction machine disclosed in Patent Document 1 may be performed. In the case where no construction target surface position signal is transmitted from the information controller 200, the target surface distance acquiring section 150 outputs the target surface distance as zero.
The target speed correction section 170 inputs a mode setting signal transmitted from the mode setting switch 32, a boom target speed signal and an arm target speed signal from the target speed computation section 120, and a target surface distance signal from the target surface distance acquiring section 150, and computes a corrected boom target speed signal and a corrected arm target speed signal obtained by correcting the target speed signals, outputting them to the hydraulic control section 130. The computation performed by the target speed correction section 170 will be described below in detail.
The hydraulic control section 130 inputs the mode setting signal transmitted from the mode setting switch 32, the target engine speed signal from the target engine speed computation section 110, the corrected boom target speed signal and the corrected arm target speed signal from the target speed correction section 170, the target surface distance signal from the target surface distance acquiring section 150, the boom angle signal with respect to the horizontal plane from the angle sensor 13a, and the horsepower adjustment signal from the horsepower adjustment dial 33, and, based on the input signals, computes a boom 1 directional control valve raising drive signal, a boom 1 directional control valve lowering drive signal, a boom 2 directional control valve raising drive signal, a boom 2 directional control valve lowering drive signal, an arm 1 directional control valve crowding drive signal, and arm 1 directional control valve dumping drive signal, an arm 2 directional control valve crowding drive signal, an arm 2 directional control valve dumping drive signal, a pump 1 directional flow rate control signal, a pump 1 horsepower control signal, a pump 2 flow rate control signal, and a pump 2 horsepower control signal, outputting drive signals each driving the corresponding solenoid proportional valves 23a, 23b, 24a, 24b, 25a, 25b, 26a, 26b, 27a, 27b, 28a, and 28b.
An example of the computation conducted by the target speed correction section 170 will be described with reference to
The boom speed correction value table 171 inputs the target surface distance signal, and computes a boom speed correction value signal in accordance with the target surface distance signal by a previously set table, outputting it to the conditional connection section 172. The conditional connection section 172 effects switching of the connection section using the mode setting signal transmitted from the mode setting switch 32 as the condition. When it is in the connection state, an input signal is outputted. More specifically, when the mode set is one of the following: 3: locus control mode, or 4: horsepower increase+locus control mode, the connection section is placed in the connection state, and a boom speed correction value signal is outputted to the addition section 173.
The addition section 173 inputs the boom speed correction value signal and the boom target speed signal before correction, and outputs the added value as the corrected boom target speed. The boom speed correction value table 171 is set such that the boom speed correction value is positive when the target surface distance is equal to or less than 0. As a result, when the work device 15 is about to get deep into the construction target surface, the boom raising speed is increased, so that it is possible to prevent the work device 15 from getting too deep into the construction target surface. However, the boom target speed may be corrected through the vector direction correction as described in Patent Document 1.
The arm speed limited value table 174 inputs the target surface distance signal, and computes an arm speed limited value signal in accordance with the target surface distance signal by a previously set table, outputting it to the conditional connection section 175. The conditional connection section 175 effects switching of the connection section using the mode setting signal transmitted from the mode setting switch 32 as the condition. When it is in the connection state, an input signal is outputted. More specifically, when the mode set is one of the following: 3: locus control mode, or 4: horsepower increase+locus control mode, the connection section is placed in the connection state, and the arm speed limited value signal is outputted to the restriction section 176.
The restriction section 176 inputs the arm speed limited value signal and the arm target speed signal before correction, and performs limitation correction such that the absolute value of the arm target speed signal before correction is equal to or less than the arm speed limited value, outputting it as the corrected arm target speed. The arm speed limited value table 174 is set such that when the target surface distance is equal to or more than B, the arm speed limited value is the maximum speed of arm crowding (or arm dumping) and that when the target surface distance is equal to or less than A, the arm speed limited value is the minimum value. Here, the target surface distance A is an index for deciding to give top priority to the finish accuracy over the operation speed and operational efficiency. It is desirable for the target surface distance A to be set to a distance of construction accuracy equal to or better than that required for the operation.
The target surface distance B is an index for determining the interference of the locus control of the work device 15. It is set based on the time it takes for the work device 15 to reach the construction target surface through the arm operation. For example, it is set to a distance equal to or more than the distance obtained by multiplying the maximum value of the speed of the work device 15 due to arm crowding by the control cycle of the main controller 100. As a result, the arm speed is limited in the vicinity of the construction target surface, and the locus of the work device 15 becomes easier to control.
Next, the hydraulic control section 130 will be described in detail with reference to the drawings.
As shown in
The target flow rate computation section 131 inputs the corrected boom target speed signal and the corrected arm target speed signal from the target speed correction section 170, and multiplies the corrected boom target speed signal by the effective area of the boom cylinder 5 to compute a boom raising target flow rate signal and a boom lowering target flow rate signal. In the case where the corrected boom target speed signal is positive, solely the boom raising target flow rate signal is computed, and in the case where the boom target speed signal is negative, solely the boom lowering target flow rate signal is computed. Similarly, by multiplying the corrected arm target speed signal by the effective area of the arm cylinder 6, the arm crowding target flow rate signal and the arm dumping target flow rate signal are computed. In the case where the arm target speed signal is positive, solely the arm crowding target flow rate signal is computed, and in the case where the arm target speed signal is negative, solely the arm dumping target flow rate signal is computed.
The directional control valve control section 132 inputs the boom raising target flow rate signal, the boom lowering target flow rate signal, the arm crowding target flow rate signal, and the arm dumping target flow rate signal from the target flow rate computation section 131, and computes drive signals for the boom 1 directional control valve 23, the boom 2 directional control valve 24, the arm 1 directional control valve 25, and the arm 2 directional control valve 26. An example of the computation conducted by the directional control valve control section 132 will be described with reference to
The directional control valve control section 132 is equipped with a boom 1 directional control valve raising drive signal table 1321, a boom 2 directional control valve raising drive signal table 1322, a maximum value selection section 1323, a boom 2 directional control valve raising drive limitation table 1324, and a minimum value selection section 1325.
The boom 1 directional control valve raising drive signal table 1321 and the boom 2 directional control valve raising drive signal table 1322 inputs the boom raising target flow rate signal calculated by the target flow rate computation section 131, and computes a boom 1 directional control valve raising drive signal and a boom 2 directional control valve raising drive signal in accordance with the boom raising target flow rate signal by a previously set table. From the boom 1 directional control valve raising drive signal table 1321, a drive signal is outputted to the solenoid proportional valve 23a.
The maximum value selection section 1323 inputs the arm crowding target flow rate signal and the arm dumping target flow rate signal calculated by the target flow rate computation section 131, and selects the maximum of the two, outputting it to the boom 2 directional control valve raising drive limitation table 1324. The boom 2 directional control valve raising drive limitation table 1324 computes a boom 2 directional control valve raising drive limitation signal in accordance with the input arm target flow rate signal by a previously set table, and outputs it to the minimum value selection section 1325.
The minimum value selection section 1325 inputs the boom 2 directional control valve raising drive signal calculated by the boom 2 directional control valve raising drive signal table 1322 and the boom 2 directional control valve raising drive signal calculated by the boom 2 directional control valve raising drive limitation table 1324, and selects the minimum value of the two, thereby limiting the boom 2 directional control valve raising drive signal to a level equal to or less than the boom 2 directional control valve raising drive signal limited value. From the minimum value selection section 1325, a drive signal is outputted to the solenoid proportional valve 24a. As a result, for example, in the case where boom raising and arm crowding are combined with each other, the boom 2 directional control valve 24 remains closed, and the hydraulic fluid is supplied to the boom cylinder 5 solely from the first hydraulic pump 21.
At the directional control valve control section 132, a computation similar to that described above is performed also on boom lowering, arm crowding, and arm dumping, so that, in the case, for example, arm crowding and boom raising are combined with each other, the arm 2 directional control valve raising drive signal is outputted to the solenoid proportional valve 26a from the minimum value selection section 1325. Due to this operation, the arm 2 directional control valve 26 remains closed, and the hydraulic fluid is supplied to the arm cylinder 6 solely from the second hydraulic pump 22.
Referring back to
The distribution ratio computation section 133 is equipped with a maximum value selection section 1331, a boom distribution ratio table 1332, and a subtraction section 1333.
The maximum value selection section 1331 inputs the boom 2 directional control valve raising drive signal and the boom 2 directional control valve lowering drive signal calculated by the directional control valve control section 132, and selects the maximum value of the two, outputting it to the boom distribution ratio table 1332. The distribution ratio table 1332 computes a boom 2 distribution ratio in accordance with the input drive signal by a previously set table, and outputs it to the subtraction section 1333, the pump flow rate control section 134, and the pump horsepower control section 135.
The subtraction section 1333 inputs a fixed value 100% signal and a boom 2 distribution ratio signal, and outputs a value obtained by subtracting the boom 2 distribution ratio signal from the fixed value 100% signal to the pump flow rate control section 134 and the pump horsepower control section 135 as a boom 1 distribution ratio signal.
Referring back to
The pump flow rate control section 134 is equipped with a maximum value selection section 1341a, a first multiplication section 1342a, a second multiplication section 1343a, a first addition section 1344a, a first division section 1345a, and a pump 1 flow rate control signal table 1346a. Further, the pump flow rate control section 134 is equipped with a maximum value selection section 1341b, a third multiplication section 1342b, a fourth multiplication section 1343b, a second addition section 1344b, a second division section 1345b, and a pump 2 flow rate control signal table 1346b.
The maximum value selection section 1341a inputs the boom raising target flow rate signal and the boom lowering target flow rate signal, and selects the maximum value of the two, outputting it to the first multiplication section 1342a and the second multiplication section 1343a. The first multiplication section 1342a multiplies the boom 1 distribution ratio signal by the boom target flow rate signal to calculate the boom 1 target flow rate signal, and outputs it to the first addition section 1344a. Similarly, the second multiplication section 1343a multiplies the boom 2 distribution ratio signal by the boom target flow rate signal to calculate the boom 2 target flow rate signal, and outputs it to the second addition section 1344b.
The maximum value selection section 1341b inputs the arm crowding target flow rate signal and the arm dumping target flow rate signal, and selects the maximum value of the two, outputting it to the third multiplication section 1342b and the fourth multiplication section 1343b. The third multiplication section 1342b multiplies the arm 2 distribution ratio signal by the arm target flow rate signal to calculate the arm 2 target flow rate signal, outputting it to the first addition section 1344a. Similarly, the fourth multiplication section 1343b multiplies the arm 1 distribution ratio signal by the arm target flow rate signal to calculate the arm 1 target flow rate signal, outputting it to the second addition section 1344b.
The first addition section 1344a adds the boom 1 target flow rate signal and the arm 2 target flow rate signal together to calculate the pump 1 target flow rate signal, and outputs it to the first division section 1345a. The first division section 1345a divides the pump 1 target flow rate signal by the input target engine speed signal to calculate the flow rate signal, and outputs it to the pump 1 flow rate control signal table 1346a. The pump 1 flow rate control signal table 1346a computes a pump 1 flow rate control signal in accordance with the input flow rate signal by a previously set table, and drives the solenoid proportional valve 27a for position tilting control.
The second addition section 1344b adds the arm 1 target flow rate signal and the boom 2 target flow rate signal together to calculate the pump 2 target flow rate signal, and outputs it to the second division section 1345b. The second division section 1345b divides the pump 2 target flow rate signal by the input target engine speed signal to calculate the flow rate signal, and outputs it to the pump 2 flow rate control signal table 1346b. The pump 2 flow rate control signal table 1346b computes a pump 2 flow rate control signal in accordance with the input flow rate signal, and drives the solenoid proportional valve 28a for positive tilting control.
In the computation up to this stage, in the case where a combined operation of the boom and the arm is performed, the boom 1 distribution ratio and the arm 1 distribution ratio are substantially 100%, and the boom 2 distribution ratio and the arm 2 distribution ratio are substantially 0%, so that the target flow rate for the boom is supplied from the first hydraulic pump 21, and the target flow rate for the arm is supplied from the second hydraulic pump 22.
Referring back to
The pump horsepower control section 135 is equipped with a boom raising target horsepower table 1351a, a boom lowering target horsepower table 1351b, a maximum value selection section 1352a, a boom maximum horsepower ratio table 1353, a first multiplication section 1354, a signal generation section 1355 setting a maximum horsepower signal, a first minimum value selection section 1356a, a subtraction section 1357, a second multiplication section 1358a, a third multiplication section 1358b, a first addition section 1359a, and a pump 1 horsepower control signal table 135Aa. Further, the pump horsepower control section 135 is equipped with an arm crowding target horsepower table 1351c, an arm dumping target horsepower table 1351d, a maximum value selection section 1352b, a second minimum value selection section 1356b, a fourth multiplication section 1358c, a fifth multiplication section 1358d, a second addition section 1359b, and a pump 2 horsepower control signal table 135Ab.
The boom raising target horsepower table 1351a inputs the horsepower adjustment signal, the boom target speed signal, and the mode setting signal, and computes a boom raising target horsepower signal in accordance with the boom target speed signal by a previously set table, and outputs it to the maximum value selection section 1352a. The boom lowering target horsepower table 1351b inputs the boom target speed signal, and computes a boom lowering target horsepower signal in accordance with the boom target speed signal by a previously set table, and outputs it to the maximum value selection section 1352a. The maximum value selection section 1352a selects the maximum value of the input signals, and outputs it to the first minimum value selection section 1356a as the boom target horsepower signal.
Similarly, using the arm crowding target horsepower table 1351c and the arm dumping target horsepower table 1351d, an arm crowding target horsepower signal and an arm dumping target horsepower signal are each computed from the arm target speed signal, and the maximum value is selected by the maximum value selection section 1352b, and is outputted to the second minimum value selection section 1356b as the arm target horsepower signal.
Here, the boom raising target horsepower table 1351a, the arm crowding target horsepower table 1351c, and the arm dumping target horsepower table 1351d correct the target horsepower signal calculated from the target speed signal in accordance with the horsepower adjustment signal (or the mode setting) and the target surface distance, and output the result. The method of correcting the target horsepower performed in accordance with the horsepower adjustment signal (or the mode setting) and the target surface distance signal will be described in detail below.
The boom maximum horsepower ratio table 1353 inputs the boom angle signal with respect to the horizontal plane, and computes a boom maximum horsepower ratio signal in accordance with the boom angle signal by a previously set table, and outputs it to the first multiplication section 1354. The first multiplication section 1354 multiplies the signal from the signal generation section 1355 setting the maximum horsepower with which the hydraulic fluid is supplied from the hydraulic pump by the boom maximum horsepower ratio signal to calculate the boom maximum horsepower signal, and outputs it to the first minimum value selection section 1356a. The first minimum value selection section 1356a corrects the boom target horsepower that is the input signal to a level equal to or less than the boom maximum horsepower signal, and outputs the result to the subtraction section 1357, the second multiplication section 1358a, and the third multiplication section 1358b.
The subtraction section 1357 subtracts the corrected boom target horsepower signal from the signal of the signal generation section 1355 setting the maximum horsepower, and outputs the result to the second minimum value selection section 1356b as the arm maximum horsepower signal. The second minimum value selection section 1356b corrects the arm target horsepower signal that is the input signal to a level equal to or less than the arm maximum horsepower signal, and outputs the result to the fourth multiplication section 1358c and the fifth multiplication section 1358d.
Here, the boom maximum horsepower ratio table 1353 is set such that the smaller the boom angle signal with respect to the horizontal plane, the larger the boom maximum horsepower ratio signal. Thus, as in the case of slope face cutting-up operation, in the case where the boom angle (and the boom cylinder stroke) is small and where the excavating reaction force is exerted so as to hinder the boom raising, it is possible to give priority to the boom in distributing the horsepower. As in the case of slope face cutting-down, in the case where the boom angle (and the boom cylinder stroke) is large and where the excavating reaction force is exerted so as to promote the boom raising, it is possible to give priority to the arm in distributing the horsepower.
The second multiplication section 1358a multiplies the boom 1 distribution ratio signal by the boom target horsepower signal to calculate the boom 1 target horsepower, and outputs it to the first addition section 1359a. The third multiplication section 1358b multiplies the boom 2 distribution ratio signal by the boom target horsepower signal to calculate the boom 2 target horsepower, and outputs it to the second addition section 1359b. Similarly, the fourth multiplication section 1358c multiplies the arm 2 distribution ratio signal by the arm target horsepower signal to calculate the arm 2 target horsepower signal, and outputs it to the first addition section 1359a. The fifth multiplication section 1358d multiplies the arm 1 distribution ratio signal by the arm target horsepower signal to calculate the arm 1 target horsepower signal, and outputs it to the second addition section 1359b.
The first addition section 1359a adds the boom 1 target horsepower signal and the arm 2 target horsepower signal together to calculate the pump 1 target horsepower signal, and outputs it to the pump 1 horsepower control signal table 135Aa. Similarly, the second addition section 1359b adds the arm 1 target horsepower signal and the boom 2 target horsepower signal together to calculate the pump 2 target horsepower signal, and outputs it to the pump 2 horsepower control signal table 135Ab.
The pump 1 horsepower control signal table 135Aa computes a pump 1 horsepower control signal in accordance with the input pump 1 target horsepower signal by a previously set table, and drives the solenoid proportional valve 27b for horsepower control. Similarly, the pump 2 horsepower control signal table 135Ab computes a pump 2 horsepower control signal in accordance with the input pump 2 target horsepower signal by a previously set table, and drives the solenoid proportional valve 28b for horsepower control.
Next, an example of the target horsepower correction method in accordance with the horsepower adjustment signal and the target surface distance signal conducted by the boom raising target horsepower table 1351a, the arm crowding target horsepower table 1351c, and the arm dumping target horsepower table 1351d will be described in detail with reference to the drawings.
The correction methods executed by the boom raising target horsepower table 1351a, the arm crowding target horsepower table 1351c, and the arm dumping target horsepower table 1351d are similar to each other, so that solely the correction method executed by the boom raising target horsepower table 1351a will be described, and a description of the correction methods executed by the arm crowding target horsepower table 1351c and the arm dumping target horsepower table 1351d will be left out.
The boom raising target horsepower table 1361 inputs the boom target speed signal, and computes a boom raising target horsepower signal in accordance with the boom target speed signal by a previously set table, and outputs it to the addition section 1366. Similarly, the boom raising increase horsepower table 1362 inputs the boom target speed signal, and computes a boom raising increase horsepower signal in accordance with the boom target speed signal by a previously set table, and outputs it to the multiplication section 1364.
The horsepower increase coefficient table 1363 inputs the target surface distance signal, and computes a horsepower increase coefficient signal in accordance with the target surface distance signal by a previously set table, outputting it to the multiplication section 1364. The multiplication section 1364 multiplies the boom raising increase horsepower signal by the horsepower increase coefficient signal to calculate the boom horsepower correction value signal, and outputs it to the variable gain multiplication section 1367.
The variable gain multiplication section 1367 inputs the horsepower adjustment signal and the boom horsepower correction value signal, and outputs to the addition section 1366 a correction signal obtained by multiplying a horsepower adjustment gain between 0 and 1 in accordance with the horsepower adjustment signal by the boom horsepower correction value signal. The addition section 1366 adds the boom raising target horsepower signal before correction and the correction value signal together, and outputs the result, for example, to the maximum value selection section 1352a as a new boom raising target horsepower signal.
Here, the horsepower increase coefficient table 1363 is set such that the horsepower increase coefficient signal increases when the target surface distance signal is equal to or less than a target surface distance B, and that the horsepower increase coefficient signal is of the maximum value when the target surface distance signal is a target surface distance A. As a result, the smaller the target surface distance signal, the larger the target horsepower signal is corrected to be. As described above, it is desirable for the target surface distance A to be set to a distance of the construction accuracy equal to or better than that required for the operation. As described above, the target surface distance B is set based on the time elapsing until the work device 15 reaches the construction target surface through the arm operation. For example, it is set to a distance equal to or more than the distance obtained by multiplying the maximum value of the speed of the work device 15 due to the arm crowding by the control cycle of the main controller 100.
The increase horsepower table 1362 is set so as to decrease the boom raising increase horsepower signal as the target speed signal increases so that even in the case where the horsepower increase coefficient signal is of the maximum value, the corrected boom target horsepower signal will increase monotonously with respect to the target speed signal. However, in order that the boom target horsepower signal becomes 0 in the case where the target speed is 0, the increase horsepower table 1362 is set such that the boom raising increase horsepower signal also becomes 0 at least when the target speed signal is 0.
Next, the method of correcting the target horsepower in accordance with the mode setting signal and the target surface distance signal will be described with reference to
As in the case where the horsepower adjustment signal shown in
In the case where the mode setting signal is 2: horsepower increase mode or 4: horsepower increase+locus control mode, the addition section 1366 adds together the boom raising target horsepower signal before correction and the boom horsepower correction value signal, and outputs the result, for example, to the maximum value selection section 1352a as a new boom raising target horsepower signal.
By performing the above computation, in the case where the mode setting is 1: normal mode, the horsepower correction value signal shown in
In the case where the mode setting is 2: horsepower increase mode or 4: horsepower increase+locus control mode and where the work device 15 performs excavating at a position relatively spaced away from the construction target surface, the output signal from the horsepower increase coefficient table 1363 is 0, and the boom horsepower correction value signal that is the output of the multiplication section 1364 is 0, so that it is possible to achieve an energy saving property equivalent to that of the prior art. On the other hand, in the case where the work device 15 performs excavating at a position relatively close to the construction target surface, the boom horsepower correction value signal that is the output of the multiplication section 1364 is added, so that solely the pump horsepower signal is increased by correction. As a result, even if the excavating load increases, it is possible to achieve predetermined finish accuracy.
In the case where the mode setting is 2: horsepower increase mode and where no construction target surface is transmitted from the information controller 200, the input of the horsepower increase coefficient table 1363 is regarded as 0, so that the boom horsepower correction value signal that is the output of the multiplication section 1364 is added, so that solely the pump horsepower signal is increased by correction. As a result, even if the excavating load increases, it is possible to achieve predetermined finish accuracy.
Next, the operation of the control system for the hydraulic construction machine according to an embodiment of the present invention will be described with reference to the drawings.
In
In
Further, the mode setting is 3: locus control mode, so that the boom target speed and the arm target speed are adjusted by the target speed correction section 170, and, as shown in portion (d), the target surface distance is maintained around 0.
When, at time T1, the arm cylinder bottom pressure is abruptly increased due to an increase in the excavating load as shown in portion (a), the second regulator 28 reduces the delivery flow rate of the second hydraulic pump 22 in response thereto as shown in portion (b). As a result, as shown in portion (c), the cylinder stroke of the arm cylinder 6 stagnates, and the balance between the boom speed and the arm speed is lost. As a result, as shown in portion (d), the target surface distance increases. In other words, the work device 15 departs from the target construction surface.
Next, the case of
As a result, as shown in portion (c), the cylinder stroke of the arm cylinder 6 does not stagnate, and the balance between the boom speed and the arm speed is maintained. As a result, as shown in portion (d), the target surface distance is controlled to a level around 0, and the work device 15 does not depart from the target construction surface.
In the control system for the hydraulic construction machine according to the embodiment of the present invention described above, the pump horsepower is correction-controlled in accordance with the distance between the work device 15 and the construction target surface, so that in the case where the work device 15 performs excavating at a position close to the construction target surface, it is possible to achieve predetermined finish accuracy even if the excavating load increases.
Further, in the control system for the hydraulic construction machine according to the embodiment of the present invention described above, there is provided a setting device allowing selection or adjustment as to which of energy saving property and speed follow-up property is to be given priority, and the pump horsepower is correction-controlled in accordance with the mode setting of the setting device, so that in the case where the work device 15 performs excavating at a position close to the construction target surface, it is possible to achieve predetermined finish accuracy even if the excavating load increases.
The present invention is not restricted to the embodiment described above but includes various modifications. For example, while the above embodiment has been described in connection with the boom cylinder 5 and the arm cylinder 6, this should not be construed restrictively.
Further, while the above embodiment has been described in detail in order to facilitate the understanding of the present invention, the present invention is not always restricted to a construction equipped with all the components described above.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-237847 | Dec 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/085685 | 12/1/2016 | WO | 00 |
