Patent Grant
10450725
This application is a 371 of PCT/JP2016/086026 filed Dec. 5, 2016 which claims priority to Foreign Application No. 2015-247138 filed Dec. 18, 2015 in Japan.
The present invention relates to a construction machine such as a hydraulic excavator and particularly relates to a construction machine provided with an electric lever-type operation device.
A hydraulic excavator that is one type of construction machine includes a self-propelled lower travel structure, an upper swing structure swingably provided on an upper side of this lower travel structure, and a work device coupled to this upper swing structure. The work device includes, for example, a boom rotatably coupled to the upper swing structure, an arm rotatably coupled to the boom, and a bucket rotatably coupled to the arm. In addition, a plurality of hydraulic cylinders (specifically a boom cylinder, an arm cylinder, and a bucket cylinder) drive the boom, the arm, and the bucket to rotate. Each hydraulic actuator is driven by a hydraulic fluid supplied from a hydraulic pump via, for example, a hydraulic pilot-type directional control valve.
Types of operation devices operated by an operator include a hydraulic pilot-type operation device and an electric lever-type operation device. The hydraulic pilot-type operation device has a plurality of pilot valves corresponding to operation directions from a neutral position of an operation lever and each generating a pilot pressure in response to an operation amount of the operation lever. Each pilot valve outputs the pilot pressure to an operation section (pressure receiving section) of the corresponding directional control valve to drive the directional control valve.
The electric lever-type operation device has a plurality of potentiometers corresponding to operation directions from a neutral position of an operation lever and each generating an operation signal (electrical signal) in response to an operation amount of the operation lever. A controller generates a command current in response to the operation signal from each potentiometer, and outputs the command current to a solenoid section of a corresponding solenoid proportional valve to drive the solenoid proportional valve. The solenoid proportional valve generates a pilot pressure proportional to the command current, and outputs the pilot pressure to the operation section of the corresponding directional control valve to drive the directional control valve.
It is known that a driving system including the electric lever-type operation device described above, the controller, the solenoid proportional valves, and the directional control valves delay in an initial response of each hydraulic actuator (in other words, in a response of each hydraulic actuator at a time of starting to operate the operation lever from the neutral positions thereof), compared with a driving system including the hydraulic pilot-type operation device described above and the directional control valves. This is because signal generation of the operation device, signal output from the operation device to the controller, signal processing by the controller, and current output from the controller to the solenoid proportional valves cause a time delay. This is also because although a spool of each solenoid proportional valve is not completely closed yet right after the operation lever returns to the neutral position, the spool of the solenoid proportional valve is completely closed and the spool delays in an initial motion when a state in which the operation lever is at the neutral position continues.
Meanwhile, Patent Document 1 discloses a driving system that includes an electric lever-type operation device, a controller outputting a command current in response to an operation signal from the operation device, and solenoid proportional-type directional control valves each driven by the command current from the controller. In addition, the controller corrects the command current to the directional control valve in such a manner that the command current is higher than a target current corresponding to an operation amount of the operation device for preset predetermined time at a time of starting to operate the operation device from a neutral position thereof.
It is considered that a technique described in Patent Document 1 may be adopted in the driving system including the electric lever-type operation device described above, the controller, the solenoid proportional valves, and the directional control valves. That is, it is considered that the controller corrects the command current to each solenoid proportional valve at the time of starting to operate the operation device from a neutral position thereof in such a manner that the command current is higher than a target current corresponding to an operation amount of the operation device for preset predetermined time. If the controller corrects command currents to all the solenoid proportional valves in the same way, it is possible to improve initial characteristics of hydraulic actuators corresponding to the solenoid proportional valves in the same way. However, in the driving system including the hydraulic pilot-type operation device described above and the directional control valves, an initial response varies in accordance with a type of hydraulic actuator. Owing to this, setting the hydraulic actuators to have similar initial characteristics irrespective of types of hydraulic actuator possibly causes an operator to feel discomfort.
The initial responses of the hydraulic actuators in the driving system including the hydraulic pilot-type operation device and the directional control valves will be described in detail.
Because of a difference in load among the hydraulic actuators, the number of directional control valves corresponding to each hydraulic actuator often differs. Specifically, for example, there is a case in which one bucket cylinder is driven by the hydraulic fluid supplied via one directional control valve, while one arm cylinder or one boom cylinder is driven by the hydraulic fluid supplied via two directional control valves. In this case, the pilot pressure is output from one pilot valve to two operation sections of the two directional control valves with respect to each of the arm cylinder and the boom cylinder. Owing to this, a time lag increases until the pilot pressure rises and the directional control valves are moved, with the result that the initial responses of the directional control valves further delay. Therefore, the initial response of the bucket cylinder is quicker than that of the arm cylinder and that of the boom cylinder.
Moreover, there is often a case in which a throttle or the like is provided as a shockless function with respect to the boom cylinder. In this case, the initial response of the arm cylinder is quicker than that of the boom cylinder.
The present invention has been achieved in the light of the circumstances described above, and an object of the present invention is to provide a construction machine that can ensure an initial response in accordance with a type of hydraulic actuator almost in a similar fashion to a case of adopting a hydraulic pilot-type operation device.
To attain the object, the present invention provides a construction machine including: a plurality of hydraulic pumps; a first directional control valve that controls a flow of a hydraulic fluid from one of the hydraulic pumps to a first hydraulic actuator; a pair of first solenoid proportional valves that generate and output pilot pressure for driving the first directional control valve; a plurality of second directional control valves that control the flow of the hydraulic fluid from the plurality of hydraulic pumps to a second hydraulic actuator; a plurality of pairs of second solenoid proportional valves that generate and output pilot pressures for driving the plurality of second directional control valves; at least one electric lever-type operation device that outputs a first operation signal for operating the first hydraulic actuator and that outputs a second operation signal for operating the second hydraulic actuator; and a controller that outputs a first command current for driving the first solenoid proportional valve in response to the first operation signal from the operation device, and that outputs a second command current for driving the second solenoid proportional valves in response to the second operation signal from the operation device. The controller includes a correction function to correct a command current in such a manner that the command current is higher than a target current corresponding to an operation amount of the operation device for preset predetermined time at a time of starting to operate the operation device from a neutral position of the operation device, and the correction function of the controller corrects the command current such that the controller corrects the first command current and does not correct the second command current or such that a correction value of the first command current is higher than a correction value of the second command current.
According to the present invention, even when the electric lever-type operation device is used, it is possible to ensure the initial response that varies in accordance with the type of hydraulic actuator almost in a similar fashion to a case of adopting the hydraulic pilot-type operation device.
A first embodiment of the present invention will be described with reference to the drawings.
The hydraulic excavator of the present embodiment includes a self-propelled lower travel structure 10, an upper swing structure 11 swingably provided on an upper side of the lower travel structure 10, and a work device 12 coupled to a front side of the upper swing structure 11.
The lower travel structure 10 includes a track frame of a generally H-shape in a view from above and crawler travel devices 13a and 13b provided on left and right sides of this track frame (only the left travel device 13a is shown in
The upper swing structure 11 is configured to swing leftward or rightward as a swing motor 4 rotates. An operation room 14 is provided in a front portion of the upper swing structure 11, while devices including an engine 15 are mounted in a rear portion of the upper swing structure 11. Travel operation devices 1a and 1b and work operation devices 2a and 2b are provided within the operation room 14. Furthermore, a gate lock lever 16 that can be vertically operated (not shown in
The work device 12 includes a boom 17 rotatably coupled to a front side of the upper swing structure 11, an arm 18 rotatably coupled to the boom 17, and a bucket 19 rotatably coupled to the arm 18. The boom 17 rotates upward or downward by expansion or contraction of a boom cylinder 5. The arm 18 rotates in a crowding direction (pull-in direction) or a dumping direction (push-out direction) by expansion or contraction of an arm cylinder 6. The bucket 19 rotates in the crowding direction or the dumping direction by expansion or contraction of a bucket cylinder 7.
The driving system of the present embodiment is generally configured with a main hydraulic control circuit and a pilot pressure control circuit.
The main hydraulic control circuit includes variable displacement hydraulic pumps 8a, 8b, and 8c driven by the engine 15, a plurality of hydraulic actuators (specifically, the left travel motor 3a, the right travel motor 3b, the swing motor 4, the boom cylinder 5, the arm cylinder 6, and the bucket cylinder 7 described above), and a plurality of hydraulic pilot-type directional control valves (specifically, a left travel directional control valve 21, a right travel directional control valve 22, a swing directional control valve 23, boom directional control valves 24a and 24b, arm directional control valves 25a and 25b, and a bucket directional control valve 26). Regulators 9a, 9b, and 9c changing pump capacities of the hydraulic pumps 8a, 8b, and 8c are provided in the hydraulic pumps 8a, 8b, and 8c, respectively.
All the directional control valves are center bypass directional control valves and classified into a first valve group connected to a delivery side of the hydraulic pump 8a, a second valve group connected to a delivery side of the hydraulic pump 8b, and a third valve group connected to a delivery side of the hydraulic pump 8c.
The first valve group includes the right travel directional control valve 22, the bucket directional control valve 26, and the boom directional control valve 24a. The right travel directional control valve 22 is connected to the bucket directional control valve 26 and the boom directional control valve 24a in tandem and connected upstream in a flow of a hydraulic fluid supplied from the hydraulic pump 8a. The bucket directional control valve 26 and the boom directional control valve 24a are connected in parallel. The hydraulic fluid from the hydraulic pump 8a is thereby preferentially supplied to the right travel directional control valve 22 over the bucket directional control valve 26 and the boom directional control valve 24a.
The second valve group includes the boom directional control valve 24b and the arm directional control valve 25a. The boom directional control valve 24b and the arm directional control valve 25a are connected in parallel. The third valve group includes the swing directional control valve 23, the arm directional control valve 25b, and the left travel directional control valve 21. The swing directional control valve 23, the arm directional control valve 25b, and the left travel directional control valve 21 are connected in parallel.
The pilot pressure control circuit includes a pilot pump 27 driven by the engine 15, the hydraulic pilot-type travel operation devices 1a and 1b, the electric lever-type work operation devices 2a and 2b, a controller (control unit) 100, a plurality of solenoid proportional valves (specifically, swing solenoid proportional valves 41a and 41b, boom solenoid proportional valves 42a, 42b, 42c, and 42d, arm solenoid proportional valves 43a, 43b, 43c, and 43d, and bucket solenoid proportional valves 44a and 44b).
The left travel operation device 1a has an operation lever that can be operated longitudinally and first and second pilot valves (not shown) each generating a pilot pressure using a delivery pressure from the pilot pump 27 as an original pressure.
The first pilot valve generates the pilot pressure in response to an operation amount of the operation lever in a direction from a neutral position to a front side thereof, outputs the pilot pressure to an operation section (pressure receiving section) on one side of the left travel directional control valve 21 via a pilot line P1, and drives a spool of the left travel directional control valve 21 to the other side thereof. The hydraulic fluid from the hydraulic pump 8c is thereby supplied to the left travel motor 3a via the left travel directional control valve 21 and the left travel motor 3a rotates frontward.
The second pilot valve generates the pilot pressure in response to an operation amount of the operation lever in a direction from the neutral position to a rear side thereof, outputs the pilot pressure to an operation section on the other side of the left travel directional control valve 21 via a pilot line P2, and drives the spool of the left travel directional control valve 21 to the one side thereof. The hydraulic fluid from the hydraulic pump 8c is thereby supplied to the left travel motor 3a via the left travel directional control valve 21 and the left travel motor 3a rotates rearward.
Likewise, the right travel operation device 1b has an operation lever that can be operated longitudinally and third and fourth pilot valves (not shown) each generating a pilot pressure using the delivery pressure from the pilot pump 27 as the original pressure.
The third pilot valve generates the pilot pressure in response to an operation amount of the operation lever in a direction from a neutral position to a front side thereof, outputs the pilot pressure to an operation section on one side of the right travel directional control valve 22 via a pilot line P3, and drives a spool of the right travel directional control valve 22 to the other side thereof. The hydraulic fluid from the hydraulic pump 8a is thereby supplied to the right travel motor 3b via the right travel directional control valve 22 and the right travel motor 3b rotates frontward.
The fourth pilot valve generates the pilot pressure in response to an operation amount of the operation lever in a direction from the neutral position to a rear side thereof, outputs the pilot pressure to an operation section on the other side of the right travel directional control valve 22 via a pilot line P4, and drives the spool of the right travel directional control valve 22 to the one side thereof. The hydraulic fluid from the hydraulic pump 8a is thereby supplied to the right travel motor 3b via the right travel directional control valve 22 and the right travel motor 3b rotates rearward.
The left work operation device 2a has an operation lever that can be operated longitudinally and laterally and first to fourth potentiometers (not shown). The first potentiometer generates an operation signal (electrical signal) in response to an operation amount of the operation lever in a direction from a neutral position to a front side thereof and outputs the operation signal to the controller 100. The second potentiometer generates an operation signal in response to an operation amount of the operation lever in a direction from the neutral position to a rear side thereof and outputs the operation signal to the controller 100. The third potentiometer generates an operation signal in response to an operation amount of the operation lever in a direction from the neutral position to a left side thereof and outputs the operation signal to the controller 100. The fourth potentiometer generates an operation signal in response to an operation amount of the operation lever in a direction from the neutral position to a right side thereof and outputs the operation signal to the controller 100.
Likewise, the right work operation device 2b has an operation lever that can be operated longitudinally and laterally and fifth to eighth potentiometers (not shown). The fifth potentiometer generates an operation signal in response to an operation amount of the operation lever in a direction from the neutral position to a front side thereof and outputs the operation signal to the controller 100. The sixth potentiometer generates an operation signal in response to an operation amount of the operation lever in a direction from the neutral position to a rear side thereof and outputs the operation signal to the controller 100. The seventh potentiometer generates an operation signal in response to an operation amount of the operation lever in a direction from the neutral position to a left side thereof and outputs the operation signal to the controller 100. The eighth potentiometer generates an operation signal in response to an operation amount of the operation lever in a direction from the neutral position to a right side thereof and outputs the operation signal to the controller 100.
The controller 100 generates a command current in response to the operation signal from the first potentiometer, outputs the command current to a solenoid section of the swing solenoid proportional valve 41a, and drives the swing solenoid proportional valve 41a. The swing solenoid proportional valve 41a generates a pilot pressure using the delivery pressure from the pilot pump 27 as the original pressure, outputs the pilot pressure to an operation section on one side of the swing directional control valve 23 via a pilot line P5, and drives a spool of the swing directional control valve 23 to the other side thereof. The hydraulic fluid from the hydraulic pump 8c is thereby supplied to the swing motor 4 via the swing directional control valve 23, and the swing motor 4 rotates in one direction.
Furthermore, the controller 100 generates a command current in response to the operation signal from the second potentiometer, outputs the command current to a solenoid section of the swing solenoid proportional valve 41b, and drives the swing solenoid proportional valve 41b. The swing solenoid proportional valve 41b generates a pilot pressure using the delivery pressure from the pilot pump 27 as the original pressure, outputs the pilot pressure to an operation section on the other side of the swing directional control valve 23 via a pilot line P6, and drives the spool of the swing directional control valve 23 to the one side thereof. The hydraulic fluid from the hydraulic pump 8c is thereby supplied to the swing motor 4 via the swing directional control valve 23, and the swing motor 4 rotates in an opposite direction.
It is noted that swing pressure sensors 31a and 31b are provided in the pilot lines P5 and P6 (in other words, secondary pressure sides of the swing solenoid proportional valves 41a and 41b), and an actual pilot pressure detected by each pressure sensor is output to the controller 100.
The controller 100 generates a command current in response to the operation signal from the third potentiometer, outputs the command current to solenoid sections of the arm solenoid proportional valves 43a and 43b, and drives the arm solenoid proportional valve 43a and 43b. The arm solenoid proportional valve 43a generates a pilot pressure using the delivery pressure from the pilot pump 27 as the original pressure, outputs the pilot pressure to an operation section on one side of the arm directional control valve 25a via a pilot line P11, and drives a spool of the arm directional control valve 25a to the other side thereof. The arm solenoid proportional valve 43b generates a pilot pressure using the delivery pressure from the pilot pump 27 as the original pressure, outputs the pilot pressure to an operation section on one side of the arm directional control valve 25b via a pilot line P12, and drives a spool of the arm directional control valve 25b to the other side thereof. The hydraulic fluid from the hydraulic pump 8b is thereby supplied to a rod side of the arm cylinder 6 via the arm directional control valve 25a and the hydraulic fluid from the hydraulic pump 8c is supplied to the rod side of the arm cylinder 6 via the arm directional control valve 25b, and the arm cylinder 6 is contracted.
Furthermore, the controller 100 generates a command current in response to the operation signal from the fourth potentiometer, outputs the command current to solenoid sections of the arm solenoid proportional valves 43c and 43d, and drives the arm solenoid proportional valve 43c and 43d. The arm solenoid proportional valve 43c generates a pilot pressure using the delivery pressure from the pilot pump 27 as the original pressure, outputs the pilot pressure to an operation section on the other side of the arm directional control valve 25a via a pilot line P13, and drives the spool of the arm directional control valve 25a to the one side thereof. The arm solenoid proportional valve 43d generates a pilot pressure using the delivery pressure from the pilot pump 27 as the original pressure, outputs the pilot pressure to an operation section on the other side of the arm directional control valve 25b via a pilot line P14, and drives the spool of the arm directional control valve 25b to the one side thereof. The hydraulic fluid from the hydraulic pump 8b is thereby supplied to a bottom side of the arm cylinder 6 via the arm directional control valve 25a and the hydraulic fluid from the hydraulic pump 8c is supplied to the bottom side of the arm cylinder 6 via the arm directional control valve 25b, and the arm cylinder 6 is expanded.
It is noted that arm pressure sensors 33a, 33b, 33c, and 33d are provided in the pilot lines P11, P12, P13, and P14 (in other words, secondary pressure sides of the arm solenoid proportional valves 43a, 43b, 43c, and 43d), and an actual pilot pressure detected by each pressure sensor is output to the controller 100.
The controller 100 generates a command current in response to the operation signal from the fifth potentiometer, outputs the command current to solenoid sections of the boom solenoid proportional valves 42a and 42b, and drives the boom solenoid proportional valve 42a and 42b. The boom solenoid proportional valve 42a generates a pilot pressure using the delivery pressure from the pilot pump 27 as the original pressure, outputs the pilot pressure to an operation section on one side of the boom directional control valve 24a via a pilot line P7, and drives a spool of the boom directional control valve 24a to the other side thereof. The boom solenoid proportional valve 42b generates a pilot pressure using the delivery pressure from the pilot pump 27 as the original pressure, outputs the pilot pressure to an operation section on one side of the boom directional control valve 24b via a pilot line P8, and drives a spool of the boom directional control valve 24b to the other side thereof. The hydraulic fluid from the hydraulic pump 8a is thereby supplied to a rod side of the boom cylinder 5 via the boom directional control valve 24a and the hydraulic fluid from the hydraulic pump 8b is supplied to the rod side of the boom cylinder 5 via the boom directional control valve 24b, and the boom cylinder 5 is contracted.
Furthermore, the controller 100 generates a command current in response to the operation signal from the sixth potentiometer, outputs the command current to solenoid sections of the boom solenoid proportional valves 42c and 42d, and drives the boom solenoid proportional valve 42c and 42d. The boom solenoid proportional valve 42c generates a pilot pressure using the delivery pressure from the pilot pump 27 as the original pressure, outputs the pilot pressure to an operation section on the other side of the boom directional control valve 24a via a pilot line P9, and drives the spool of the boom directional control valve 24a to the one side thereof. The boom solenoid proportional valve 42d generates a pilot pressure using the delivery pressure from the pilot pump 27 as the original pressure, outputs the pilot pressure to an operation section on the other side of the boom directional control valve 24b via a pilot line P10, and drives the spool of the boom directional control valve 24b to the one side thereof. The hydraulic fluid from the hydraulic pump 8a is thereby supplied to a bottom side of the boom cylinder 5 via the boom directional control valve 24a and the hydraulic fluid from the hydraulic pump 8b is supplied to the bottom side of the boom cylinder 5 via the boom directional control valve 24b, and the boom cylinder 5 is expanded.
It is noted that boom pressure sensors 32a, 32b, 32c, and 32d are provided in the pilot lines P7, P8, P9, and P10 (in other words, secondary pressure sides of the boom solenoid proportional valves 42a, 42b, 42c, and 42d), and an actual pilot pressure detected by each pressure sensor is output to the controller 100.
The controller 100 generates a command current in response to the operation signal from the seventh potentiometer, outputs the command current to a solenoid section of the bucket solenoid proportional valve 44a, and drives the bucket solenoid proportional valve 44a. The bucket solenoid proportional valve 44a generates a pilot pressure using the delivery pressure from the pilot pump 27 as the original pressure, outputs the pilot pressure to an operation section on one side of the bucket directional control valve 26 via a pilot line P15, and drives a spool of the bucket directional control valve 26 to the other side thereof. The hydraulic fluid from the hydraulic pump 8a is thereby supplied to a bottom side of the bucket cylinder 7 via the bucket directional control valve 26 and the bucket cylinder 7 is expanded.
Furthermore, the controller 100 generates a command current in response to the operation signal from the eighth potentiometer, outputs the command current to a solenoid section of the bucket solenoid proportional valve 44b, and drives the bucket solenoid proportional valve 44b. The bucket solenoid proportional valve 44b generates a pilot pressure using the delivery pressure from the pilot pump 27 as the original pressure, outputs the pilot pressure to an operation section on the other side of the bucket directional control valve 26 via a pilot line P16, and drives the spool of the bucket directional control valve 26 to the one side thereof. The hydraulic fluid from the hydraulic pump 8a is thereby supplied to a rod side of the bucket cylinder 7 via the bucket directional control valve 26 and the bucket cylinder 7 is contracted.
It is noted that bucket pressure sensors 34a and 34b are provided in the pilot lines P15 and P16 (in other words, secondary pressure sides of the bucket solenoid proportional valves 44a and 44b), and an actual pilot pressure detected by each pressure sensor is output to the controller 100.
The controller 100 determines whether abnormality occurs to each solenoid proportional valve on the basis of the command current to each solenoid proportional valve and the actual pilot pressure detected by the pressure sensor on the secondary pressure side thereof. When determining that abnormality occurs to the solenoid proportional valve, the controller 100 displays an abnormal state of the solenoid proportional valve on a display apparatus 50 to notify an operator of the abnormal state.
A relief valve 28 is provided on a delivery side of the pilot pump 27 and configured to specify an upper limit value of the delivery pressure of the pilot pump 27. In addition, a gate lock valve 29 is provided between the pilot pump 27 and the first to fourth pilot valves and the solenoid proportional valves 41a, 41b, 42a to 42d, 43a to 43d, 44a and 44b described above.
When the gate lock lever 16 is operated to a rising position (lock position), a switch is opened and a solenoid section of the gate lock valve 29 is not excited; thus, the gate lock valve 29 is located at a neutral position that is a lower side in
Details of the controller 100 that is a principal part of the present embodiment will next be described.
The controller 100 according to the present embodiment has eight target pilot pressure computing sections 110 (only one representative target pilot pressure computing section 110 is shown in
Each target pilot pressure computing section 110 computes a target pilot pressure for the operation signal input from the corresponding potentiometer using a relationship between the operation amount of the operation lever (in other words, operation signal) and the target pilot pressure shown in
Each command current computing section 111 computes a target current for the target pilot pressure input from the corresponding target pilot pressure computing section 110 using a relationship between the target pilot pressure and the target current shown in
As a notable feature of the present embodiment, only the two command current computing sections 111 related to the bucket cylinder 7 (that is, corresponding to the bucket solenoid proportional valves 44a and 44b) have a function to correct the command current. More specifically, each of the two command current computing sections 111 has the function to correct the command current in such a manner that the command current is higher than the target current for preset predetermined time at a time of starting to operate the work operation device 2b in the direction from the neutral position to the left or right side thereof. That is, at the time of starting to operate the work operation device 2b in the direction from the neutral position to the left or right side thereof, a preset correction value y of the command current (hereinafter, referred to as precharge current) is output to the solenoid section of either the bucket solenoid proportional valve 44a or 44b in such a manner that the command current is higher than the target current for the predetermined time as shown in
First, in Step S210, the command current computing section 111 related to the bucket cylinder 7 determines whether the actual pilot pressure detected by the bucket pressure sensor 34a or 34b (in other words, the pilot pressure generated by the bucket solenoid proportional valve 44a or 44b) is equal to or lower than a preset predetermined threshold x [MPa]. When the actual pilot pressure detected by the bucket pressure sensor 34a or 34b is equal to or lower than the predetermined threshold x, then a determination result of Step S210 is YES, and processing goes to Step S220, in which the command current computing section 111 counts up timer time. Subsequently, the processing goes to Step S230, in which the command current computing section 111 determines whether the target pilot pressure input from the target pilot pressure computing section 110 is higher than zero and whether the timer time is equal to or longer than preset predetermined time t. When the target pilot pressure is zero or when the timer time is shorter than the predetermined threshold t, then a determination result of Step S230 is NO, the processing returns to Step S210 described above, and similar procedures to those described above are repeated.
When the actual pilot pressure detected by the bucket pressure sensor 34a or 34b is higher than the predetermined threshold x in Step S210, then the determination result of Step S210 is NO, and the processing goes to Step S240, in which the command current computing section 111 resets the timer time.
When the target pilot pressure is higher than zero and the timer time is equal to or longer than the predetermined threshold t, then the determination result of Step S230 is YES, and the processing goes to Step S250. In Step S250, the command current computing section 111 corrects the command current in such a manner that the command current is higher than the target current for the predetermined time. That is, the command current computing section 111 outputs the precharge current y to the solenoid section of the bucket solenoid proportional valve 44a or 44b for the predetermined time.
Actions in the present embodiment will next be described with reference to
In
In
According to the present embodiment described above, it is possible to quicken only the initial response of the bucket cylinder 7. Therefore, it is possible to ensure the initial response that varies in accordance with the type of hydraulic actuator almost in a similar fashion to the case of adopting the hydraulic pilot-type operation device. As a consequence, the operator can operate the operation device without feeling discomfort.
A second embodiment of the present invention will next be described. In the present embodiment, equivalent parts to those in the first embodiment are denoted by the same reference characters and description thereof will be omitted as appropriate.
In the controller 100 according to the present embodiment, not only the two command current computing sections 111 related to the bucket cylinder 7 (that is, corresponding to the bucket solenoid proportional valves 44a and 44b, respectively) but also the four command current computing sections 111 related to the arm cylinder 6 (that is, corresponding to the arm solenoid proportional valves 43a to 43d, respectively), the four command current computing sections 111 related to the boom cylinder 5 (that is, corresponding to the boom solenoid proportional valves 42a to 42d, respectively), and the two command current computing sections 111 related to the swing motor 4 (that is, corresponding to the swing solenoid proportional valves 41a and 41b, respectively) have the function to correct the command current. The second embodiment will be described in detail.
Each of the command current computing sections 111 related to the bucket cylinder 7 corrects the command current in such a manner that the command current is higher than the target current for the preset predetermined time at the time of starting to operate the work operation device 2b in the direction from the neutral position to the left or right side thereof (specifically, when the state in which the actual pilot pressure detected by the bucket pressure sensor 34a or 34b is equal to or lower than the predetermined threshold x continues for the predetermined time t or longer and when the target pilot pressure input from the target pilot pressure computing section is higher than zero, similarly to the first embodiment). That is, as shown in
Each of the command current computing sections 111 related to the arm cylinder 6 corrects the command current in such a manner that the command current is higher than the target current for the predetermined time at the time of starting to operate the work operation device 2a in the direction from the neutral position to the left or right side thereof (specifically, when a state in which the actual pilot pressures detected by the arm pressure sensors 33a and 33b or 33c and 33d are equal to or lower than the predetermined threshold x continues for the predetermined time t or longer and when the target pilot pressure input from each target pilot pressure computing section is higher than zero). That is, as shown in
Each of the command current computing sections 111 related to the boom cylinder 5 corrects the command current in such a manner that the command current is higher than the target current for the predetermined time at the time of starting to operate the work operation device 2b in the direction from the neutral position to the front or rear side thereof (specifically, when a state in which the actual pilot pressures detected by the boom pressure sensors 32a and 32b or 32c and 32d are equal to or lower than the predetermined threshold x continues for the predetermined time t or longer and when the target pilot pressure input from each target pilot pressure computing section is higher than zero). That is, as shown in
Each of the command current computing sections 111 related to the swing motor 4 corrects the command current in such a manner that the command current is higher than the target current for the preset predetermined time at the time of starting to operate the work operation device 2a in the direction from the neutral position to the front or rear side thereof (specifically, when a state in which the actual pilot pressure detected by the swing pressure sensor 31a or 31b is equal to or lower than the predetermined threshold x continues for the predetermined time t or longer and when the target pilot pressure input from the target pilot pressure computing section is higher than zero). That is, although not shown, a preset precharge current y0 (where y0 is nearly equal to y3) set such that the precharge current y0 is higher than the target current for the predetermined time is output to the solenoid section of the swing solenoid proportional valve 41a or 41b. It is thereby possible to advance rising of the actual pilot pressure, compared with a case in which the precharge current y0 is not output. Therefore, it is possible to quicken an initial response of the swing motor 4.
Furthermore, a relationship of the initial response of the bucket cylinder 7>the initial response of the arm cylinder 6>the initial response of the boom cylinder 5, that is, a relationship among the initial responses for realizing operational feeling similar to that by the hydraulic pilot-type operation device can be obtained from the relationship among the precharge currents (y1>y2>y3) described above. Therefore, it is possible to ensure the initial response that varies in accordance with the type of hydraulic actuator almost in a similar fashion to the case of adopting the hydraulic pilot-type operation device. As a consequence, even when the electric lever-type operation device is used, the operator can operate the electric lever-type operation device without feeling discomfort, compared with the case of adopting the hydraulic pilot-type operation device.
A third embodiment of the present invention will next be described. In the present embodiment, equivalent parts to those in the first and second embodiments are denoted by the same reference characters and description thereof will be omitted as appropriate.
Like the controller 100, a controller 100A of the present embodiment includes the target pilot pressure computing sections 110 and the command current computing sections 111. The controller 100A further includes a mode control section 112, which has a function to selectively execute a manual control mode and an automatic control mode.
A setting device 113 within the operation room 14 selects one of the manual control mode and the automatic control mode in response to operator's operation, and a control parameter when the automatic control mode is selected can be input to the setting device 113. When the manual control mode is selected, a manual control mode setting command is output from the setting device 113 to the mode control section 112 and each command current computing section 111. When the automatic control mode is selected, an automatic control mode setting command is output from the setting device 113 to the mode control section 112 and each command current computing section 111.
The manual control mode is a mode for driving the swing motor 4, the boom cylinder 5, the arm cylinder 6, and the bucket cylinder 7 in accordance with operation on the operation devices 2a and 2b. The automatic control mode is a mode for driving the swing motor 4, the boom cylinder 5, the arm cylinder 6, and the bucket cylinder 7 on the basis of operation on the operation devices 2a and 2b in such a manner that an action of any one of the upper swing structure 11, the boom 17, the arm 18, and the bucket 19 is limited or adjusted. Concrete examples of the automatic control mode include a mode for limiting a moving range of the bucket 19 and a mode for adjusting a moving locus of the bucket 19.
When the manual control mode is set, the mode control section 112 outputs the operation signals from the work operation devices 2a and 2b to the target pilot pressure computing sections 110 as they are. On the other hand, when the automatic control mode is set, the mode control section 112 computes an action position of any one of the upper swing structure 11, the boom 17, the arm 18, and the bucket 19 on the basis of a detection value of a sensor. Furthermore, the mode control section 112 computes a command signal for limiting or adjusting the action of any one of the upper swing structure 11, the boom 17, the arm 18, and the bucket 19 on the basis of the operation signal from the work operation device 2a or 2b, and outputs the computed command signal to the corresponding target pilot pressure computing section 110.
Each of the command current computing sections 111 related to the bucket cylinder 7 corrects the command current in such a manner that the command current is higher than the target current for the preset predetermined time at the time of starting to operate the work operation device from the neutral position thereof (specifically, when the state in which the actual pilot pressure detected by the bucket pressure sensor 34a or 34b is equal to or lower than the predetermined threshold x continues for the predetermined time t or longer and when the target pilot pressure input from the target pilot pressure computing section is higher than zero). At this time, when the manual control mode is set, the preset precharge current y1 set such that the precharge current y1 is higher than the target current for the predetermined time is output to the solenoid section of the bucket solenoid proportional valve 44a or 44b similarly to the second embodiment. On the other hand, when the automatic control mode is set, a preset precharge current y4 (where y4>y1) set such that the precharge current y4 is higher than the target current for the predetermined time is output to the solenoid section of the bucket solenoid proportional valve 44a or 44b as shown in
Each of the command current computing sections 111 related to the arm cylinder 6 corrects the command current in such a manner that the command current is higher than the target current for the predetermined time at the time of starting to operate the work operation device from the neutral position thereof (specifically, when the state in which the actual pilot pressures detected by the arm pressure sensors 33a and 33b or 33c and 33d are equal to or lower than the predetermined threshold x continues for the predetermined time t or longer and when the target pilot pressure input from each target pilot pressure computing section is higher than zero). At this time, when the manual control mode is set, the preset precharge current y2 (where y1>y2) set such that the precharge current y2 is higher than the target current for the predetermined time is output to the solenoid sections of the arm solenoid proportional valves 43a and 43b or 43c and 43d similarly to the second embodiment. On the other hand, when the automatic control mode is set, the preset precharge current y4 (where y4>y2) set such that the precharge current y4 is higher than the target current for the predetermined time is output to the solenoid sections of the arm solenoid proportional valves 43a and 43b or 43c and 43d. It is thereby possible to advance the rising of the actual pilot pressure, compared with a case in which the precharge current y2 or y4 is not output. Therefore, it is possible to quicken the initial response of the arm cylinder 6.
Each of the command current computing sections 111 related to the boom cylinder 5 corrects the command current in such a manner that the command current is higher than the target current for the predetermined time at the time of starting to operate the work operation device from the neutral position thereof (specifically, when the state in which the actual pilot pressures detected by the boom pressure sensors 32a and 32b or 32c and 32d are equal to or lower than the predetermined threshold x continues for the predetermined time t or longer and when the target pilot pressure input from each target pilot pressure computing section is higher than zero). At this time, when the manual control mode is set, the preset precharge current y3 (where y2>y3) set such that the precharge current y3 is higher than the target current for the predetermined time is output to the solenoid sections of the boom solenoid proportional valves 42a and 42b or 42c and 42d similarly to the second embodiment. On the other hand, when the automatic control mode is set, the preset precharge current y4 (where y4>y3) set such that the precharge current y4 is higher than the target current for the predetermined time is output to the solenoid sections of the boom solenoid proportional valves 42a and 42b or 42c and 42d. It is thereby possible to advance the rising of the actual pilot pressure, compared with a case in which the precharge current y3 or y4 is not output. Therefore, it is possible to quicken the initial response of the boom cylinder 5.
Each of the command current computing sections 111 related to the swing motor 4 corrects the command current in such a manner that the command current is higher than the target current for preset predetermined time at the time of starting to operate the work operation device from the neutral position thereof (specifically, when the state in which the actual pilot pressure detected by the swing pressure sensor 31a or 31b is equal to or lower than the predetermined threshold x continues for the predetermined time t or longer and when the target pilot pressure input from the target pilot pressure computing section is higher than zero). At this time, when the manual control mode is set, the preset precharge current y0 (where y0 is nearly equal to y3) set such that the precharge current y0 is higher than the target current for the predetermined time is output to the solenoid section of the swing solenoid proportional valve 41a or 41b similarly to the second embodiment. On the other hand, when the automatic control mode is set, the preset precharge current y4 (where y4>y0) is output to the solenoid section of the swing solenoid proportional valves 41a or 41b. It is thereby possible to advance the rising of the actual pilot pressure, compared with a case in which the precharge current y0 or y4 is not output. Therefore, it is possible to quicken the initial response of the swing motor 4.
According the present embodiment described above, in the manual control mode, the relationship of the initial response of the bucket cylinder 7>the initial response of the arm cylinder 6>the initial response of the boom cylinder 5, that is, the relationship among the initial responses for realizing the operational feeling similar to that by the hydraulic pilot-type operation device can be obtained from the relationship among the precharge currents (y1>y2>y3) similarly to the second embodiment. Therefore, it is possible to ensure the initial response that varies in accordance with the type of hydraulic actuator almost in the similar fashion to the case of adopting the hydraulic pilot-type operation device. As a consequence, even when the electric lever-type operation device is used, the operator can operate the electric lever-type operation device without feeling discomfort, compared with the case of adopting the hydraulic pilot-type operation device.
On the other hand, in the automatic control mode, responsiveness of each hydraulic actuator takes precedence over operator's operability. That is, in the automatic control mode, the precharge currents are high and the initial responses of the hydraulic actuators can be improved, compared with the manual control mode. Therefore, it is possible to improve work efficiency.
The third embodiment has been described while a case in which the command current computing sections 111 related to the bucket cylinder 7, the arm cylinder 6, the boom cylinder 5, and the swing motor 4 output the precharge current y4 when the automatic control mode is set by way of example. However, the third embodiment is not limited to the case. That is, any of the command current computing sections 111 related to the bucket cylinder 7, the arm cylinder 6, the boom cylinder 5, or the swing motor 4 may output the precharge current y4 when the automatic control mode is set, while the remainder may output the same precharge currents as those in the manual control mode even when the automatic control mode is set. Such a modification can also attain effects similar to those described above.
The first to third embodiments have been described while a case in which the construction machine includes the hydraulic pilot-type travel operation devices is taken by way of example. However, the present invention is not limited to the case and the construction machine may include electric lever-type travel operation devices.
Furthermore, the first to third embodiments have been described while the hydraulic excavator is used as an object to which the present invention is applied. However, the object to which the present invention is applied is not limited to the hydraulic excavator but may be another construction machine. Specifically, the present invention may be applied to, for example, a wheel loader including: a plurality of hydraulic pumps; a bucket directional control valve that controls a flow of a hydraulic fluid from one of the hydraulic pumps to a bucket cylinder; a pair of bucket solenoid proportional valves that generate and output pilot pressures for driving the bucket directional control valve; a plurality of arm directional control valves that control the flow of the hydraulic fluid from the plurality of hydraulic pumps to an arm cylinder; a plurality of pairs of arm solenoid proportional valves that generate and output pilot pressures for driving the plurality of arm directional control valves; an electric lever-type operation device that outputs a first operation signal for operating the bucket cylinder and that outputs a second operation signal for operating the arm cylinder; and a controller that outputs a first command current for driving the bucket solenoid proportional valve in response to the first operation signal from the operation device, and that outputs a second command current for driving the arm solenoid proportional valves in response to the second operation signal from the operation device.
When the present invention is applied to the wheel loader described above, the controller includes a correction function to correct a command current in such a manner that the command current is higher than a target current corresponding to an operation amount of the operation device for preset predetermined time at a time of starting to operate the operation device from a neutral position of the operation device. In addition, the correction function of the controller may correct the first command current for driving the bucket cylinder and not correct the second command current for driving the arm cylinder, similarly to the first embodiment. Alternatively, the correction function may correct the first and second command currents in such a manner that a correction value z1 of the first command current is larger than a correction value z2 of the second command current, similarly to the second embodiment. In another alternative, when the automatic control mode is set, the correction function may correct the first and second command currents to a correction value z3 higher than the correction values z1 and z2, similarly to the third embodiment. In these cases, it is possible to attain similar effects to those described above.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-247138 | Dec 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/086026 | 12/5/2016 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2017/104459 | 6/22/2017 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 7802971 | Schneider | Sep 2010 | B2 |
| 7878770 | Oka | Feb 2011 | B2 |
| 8701396 | Narotham | Apr 2014 | B2 |
| 8899143 | Ho | Dec 2014 | B2 |
| 20020014075 | Sawada | Feb 2002 | A1 |
| 20020104430 | Yamaguchi | Aug 2002 | A1 |
| 20090308603 | Borgstadt | Dec 2009 | A1 |
| 20130263587 | Azuma | Oct 2013 | A1 |
| 20150040552 | Hashimoto | Feb 2015 | A1 |
| 20160025113 | Hiraku | Jan 2016 | A1 |
| 20170159265 | Tomita | Jun 2017 | A1 |
| 20180066416 | Hijikata | Mar 2018 | A1 |
| Number | Date | Country |
|---|---|---|
| 05-195546 | Aug 1993 | JP |
| 2012-141014 | Jul 2012 | JP |
| Entry |
|---|
| International Search Report of PCT/JP2016/086026 dated Feb. 7, 2017. |
| International Preliminary Report on Patentability received in corresponding International Application No. PCT/JP2016/086026 dated Jun. 28, 2018. |
| Number | Date | Country | |
|---|---|---|---|
| 20180305898 A1 | Oct 2018 | US |
