Drive control device for electric hydraulic pump

Abstract

A drive control device that is for an electric hydraulic pump and that controls a hydraulic pump which is driven by an electric motor and which discharges pressurized oil for driving an actuator, said drive control device comprising: an inverter that receives input of an input current and that outputs, to the electric motor, a torque current in accordance with the load of the electric motor; and a control device that controls the hydraulic pump and the inverter, wherein the control device controls the hydraulic pump with a detection signal based on the input current and a detection signal based on the torque current, so that the torque current does not become an overcurrent.

Description

Electric hydraulic pump drive control device

[0001] The present invention relates to a drive control device for an electric hydraulic pump.

[0002] Electric hydraulic pumps are used as a driving force generation source in work machines such as crawler cranes. The hydraulic pump is driven by an electric motor such as a three-phase induction motor. The pressurized oil discharged from the hydraulic pump is supplied to an actuator such as a hydraulic motor via a control valve (hydraulic control circuit). This pressurized oil drives the actuator in accordance with the load. The drive control of such electric hydraulic pumps is performed by controlling the current (torque current) supplied to the electric motor. The torque current is output to the electric motor via an inverter. The inverter converts power supplied from a power source such as a battery, a generator, or a commercial power source into AC power required to drive the electric motor and outputs the converted power (see Patent Document 1 listed below).

[0003] International Publication No. 2011 / 077714

[0004] In a system in which a hydraulic pump is driven by an electric motor and an actuator is driven by the pressure oil discharged by the hydraulic pump, the rotation of the electric motor is controlled to obtain the hydraulic pump discharge pressure P (MPa) and discharge flow rate Q (l / min) required to drive the actuator. When the power supply voltage is constant, the hydraulic pump generates the required driving force (P x Q x 1 / 60 (kW)) by controlling the current (torque current (A)) output by the inverter. In such a system, when the load on the actuator (i.e., the load on the electric motor) changes, the torque current changes accordingly.

[0005] In response to this, inverters that output torque current are generally equipped with a protection circuit against overcurrent. If the torque current becomes excessive due to the load on the motor, the aforementioned protection circuit will activate and the inverter will stop output. If this occurs, the actuator of a work machine such as a crane or aerial work platform may stop during operation, making it difficult to ensure the safety and continuity of the work.

[0006] One possible solution to this problem is to detect the inverter's output current and control it accordingly to respond to increases in torque current. However, if a sudden load change occurs at a timing shorter than the output current detection cycle, an overcurrent may occur instantaneously, causing the inverter output to stop. For this reason, there has been a demand for control that allows work to continue safely without stopping the inverter's output even in the event of a sudden load change.

[0007] The present invention has been proposed to address such circumstances, and aims to provide a drive control device for an electric hydraulic pump that can avoid work stoppages due to overloading of the electric motor or sudden load fluctuations, and allows work to be continued safely.

[0008] One aspect of the drive control device for an electric hydraulic pump according to the present invention is a drive control device for an electric hydraulic pump that is driven by an electric motor and controls a hydraulic pump that discharges pressurized oil to drive an actuator, and includes: an inverter that receives an input current and outputs a torque current to the electric motor according to the load on the electric motor; and a control device that controls the hydraulic pump and the inverter, and the control device controls the hydraulic pump using a detection signal based on the input current and a detection signal based on the torque current so that the torque current does not become an overcurrent.

[0009] According to the present invention described above, it is possible to provide a drive control device for an electric hydraulic pump that can avoid work stoppages due to overloading of the electric motor or sudden load fluctuations, and allows work to be continued safely.

[0010] FIG. 1 is a block diagram showing an example of an application (crawler crane) of a drive control device for an electric hydraulic pump according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing an example of application (crawler crane) of a drive control device for an electric hydraulic pump according to an embodiment of the present invention. FIG. 3 is an explanatory diagram of an actuator to which pressure oil is supplied via a control valve. FIG. 4 is an explanatory diagram showing a basic operation flow in a drive control device for an electric hydraulic pump according to an embodiment of the present invention. FIG. 5 is a diagram showing an FF table used for proportional valve current value setting control. FIG. 6 is a diagram showing state divisions in proportional valve current value setting control. FIG. 7 is a state transition diagram used for proportional valve current value setting control. FIG. 8 is a graph showing an example of operation of a drive control device for an electric hydraulic pump according to an embodiment of the present invention. FIG. 9 is an explanatory diagram showing an example of state transition control in a drive control device for an electric hydraulic pump according to an embodiment of the present invention.

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals in different drawings denote parts with the same functions, and duplicated descriptions in each drawing will be omitted as appropriate.

[0012] 1 shows the system configuration of a drive control device for an electric hydraulic pump (hereinafter referred to as the drive control device) according to an embodiment of the present invention. The drive control device 1 includes a hydraulic pump 2, an electric motor 3, an inverter 4, and a control device 5. In the drawing, thick lines indicate oil paths, solid lines indicate current paths, and dashed lines indicate signal paths.

[0013] The hydraulic pump 2 discharges pressure oil for driving an actuator (not shown) to a control valve 6. The hydraulic pump 2 is a variable displacement pump, and its discharge capacity can be changed by the operation of an electromagnetic proportional valve 2A for controlling the driving force.

[0014] The electromagnetic proportional valve 2A operates in accordance with the input proportional valve current value, with the maximum discharge capacity at the maximum proportional valve current value, and the discharge capacity decreasing in proportion to the decrease in the proportional valve current value.

[0015] The electric motor 3 is a three-phase induction motor that is directly connected to the hydraulic pump 2 and rotates the hydraulic pump 2. The inverter 4 outputs to the electric motor 3 an electric motor current that corresponds to the load of the electric motor 3.

[0016] Here, power from a commercial power source 7 (e.g., 6000 V, three-phase, 60 Hz) is supplied to the inverter 4 via a high-voltage starting panel 8. The commercial power source 7 corresponds to an example of a power source. Note that the power source is not limited to a commercial power source, and may be a battery or a generator. The power (in other words, current) input from the power source to the inverter 4 corresponds to an example of input power (in other words, input current).

[0017] The output of the inverter 4 is controlled to change the motor current in accordance with the load on the motor 3. Hereinafter, the output of the inverter 4 will be referred to as the torque current (in other words, the output current). The inverter 4 is equipped with a protection circuit that stops operation if the output current (i.e., the torque current) becomes an overcurrent.

[0018] The control device 5 controls the driving force of the hydraulic pump 2 and the output of the inverter 4. When operation signals OS1, OS2 are input from the accelerator pedal 10 and / or the operation lever 11, the control device 5 outputs control signals CS1, CS2, CS3 to operate the selected actuators with the desired driving force.

[0019] The control signal CS1 is a signal for selecting and operating an actuator, and is output to the control valve 6. The control signal CS2 controls the frequency of the current (torque current) output by the inverter 4, and controls the rotation speed of the electric motor 3.

[0020] The control signal CS3 is output to the electromagnetic proportional valve 2A in order to control the driving force of the hydraulic pump 2. The control signal CS3 controls the electromagnetic proportional valve 2A at a set proportional valve current value.

[0021] The control device 5 has, as its hardware configuration, an arithmetic processing unit such as a CPU, a memory unit in which programs and data are stored, etc. The control device 5 has, as its functional units, at least an actuator control unit 5A that outputs a control signal CS1, an electric motor rotation speed control unit 5B that outputs a control signal CS2, and a proportional valve current control unit 5C that outputs a control signal CS3.

[0022] In order to operate each functional unit, the control device 5 receives the first detection signal DS1 and the second detection signal DS2 in addition to the operation signals OS1 and OS2 described above.

[0023] The first detection signal DS1 is a detection signal based on the output current (i.e., torque current) output by the inverter 4 detected by the current detection unit 4A.

[0024] The second detection signal DS2 is a detection signal based on the supply current (i.e., input current) from the commercial power supply 7 to the inverter 4. The second detection signal DS2 is a signal detected by a current detection unit (not shown) provided in the high-voltage start-up panel 8.

[0025] Here, the supply current to the inverter 4 (i.e., the input current) is a current from which the output current (i.e., the torque current) output by the inverter 4 can be estimated, and therefore, hereinafter, it is sometimes referred to as the converted current.

[0026] The control device 5 operates the proportional valve current control unit 5C using the first detection signal DS1 and the second detection signal DS2, thereby controlling the driving force of the hydraulic pump 2 so that the torque current described above does not become an overcurrent.

[0027] The detection period of the second detection signal DS2 is set to be shorter than the detection period of the first detection signal DS1.

[0028] For example, when the detection period of the first detection signal DS1 is set to 0.3 seconds, the detection period of the second detection signal DS2 is set to less than 0.3 seconds (for example, 0.01 seconds).

[0029] Since the second detection signal DS2 provides information that can detect a sign of a fluctuation in the torque current, by making the detection period shorter than the detection period of the first detection signal DS1, it is possible to reduce the driving force of the hydraulic pump 2 before the torque current becomes an overcurrent. Hereinafter, the detection period of the first detection signal DS1 will be referred to as the "first detection period," and the detection period of the second detection signal DS2 will be referred to as the "second detection period."

[0030] 2 and 3 show an application example of the drive control device 1 (a crawler crane and its actuator).

[0031] In Figure 2, the crawler crane 100 has left and right running bodies 101, 102, a rotating body 104 rotatably mounted on the running bodies 101, 102 via a rotating device 103, a boom 105 attached to the tip of the rotating body 104 so that it can be raised and lowered, and sheaves 110, 111 and sheaves 112, 113 provided at the tip of the boom 105.

[0032] A bucket 117 as an attachment is suspended so as to be able to rise and fall by a main hoisting rope 115 passing through sheaves 110 and 112 and an auxiliary hoisting rope 116 passing through sheaves 111 and 113 .

[0033] A cab 120 is provided on the rotating body 104. Inside the cab 120, an operator operates the accelerator pedal 10 and / or the control lever 11 shown in FIG.

[0034] The main hoisting rope 115 and the auxiliary hoisting rope 116 are wound around a main hoisting winch (not shown) and an auxiliary hoisting winch (not shown) mounted on the rotating body 104, respectively. The main hoisting rope 115 and the auxiliary hoisting rope 116 are wound up or unwound by driving the corresponding winches, causing the load suspended by the bucket 117 to rise or fall.

[0035] A pendant rope 118 is connected to the tip of the boom 105. When the hoisting rope 119 is wound or unwound by driving a hoisting winch (not shown) mounted on the rotating body 104, the boom 105 is raised or lowered via the pendant rope 118. The operation of raising or lowering the boom 105 is also performed using an operating lever inside the cab 120.

[0036] 3 shows an actuator to which pressure oil is supplied from the control valve 6. As an example, the left and right traveling bodies 101 and 102 described above are driven by hydraulic motors 6A and 6B.

[0037] In addition, the hydraulic motor 6C drives the aforementioned slewing device 103. In addition, the hydraulic motor 6D drives the aforementioned main hoisting winch. In addition, the hydraulic motor 6E drives the aforementioned auxiliary hoisting winch. In addition, the hydraulic motor 6F drives the aforementioned hoisting winch.

[0038] The following describes in detail the control performed by the drive control device 1. Fig. 4 shows the basic operation of the drive control device 1 (in other words, current control).

[0039] When control is started by the operator operating the accelerator pedal 10 or the control lever 11, the drive control device 1 (in other words, the control device 5) determines whether or not the operation signals OS1, OS2 are present (step S1).

[0040] Next, if an operation signal is present (step S1: YES), the drive control device 1 (in other words, the control device 5) continues the current control. On the other hand, if an operation signal is not present (step S1: NO), the drive control device 1 (in other words, the control device 5) ends the current control.

[0041] Next, the drive control device 1 (in other words, the control device 5) sets the proportional valve current value of the control signal CS3 to a maximum value (for example, 750 mA) (step S2).

[0042] Next, the drive control device 1 (i.e., the control device 5) acquires the first detection signal DS1 at a preset first detection period (step S3), and then acquires the second detection signal DS2 at a preset second detection period (step S4).

[0043] The control process of step S3 and the control process of step S4 may be performed alternately depending on the relationship between the first detection cycle and the second detection cycle.

[0044] Next, the drive control device 1 (in other words, the control device 5) controls the proportional valve current value setting to be output to the electromagnetic proportional valve 2A in the proportional valve current control section 5C (see FIG. 1) (step S5).

[0045] Here, the drive control device 1 (specifically, the control device 5) outputs a control signal CS1 for operating the actuator with a desired driving force based on the operation signals OS1 and OS2.

[0046] This control signal CS1 is input to the control valve 6. Then, based on the control signal CS1, the control valve 6 adjusts the opening of a valve for supplying pressure oil to an actuator (not shown).

[0047] When the valve opening is adjusted in the control valve 6 and the amount of pressure oil supplied to the actuator via the control valve 6 increases, the load on the electric motor 3 increases. As a result, the torque current supplied from the inverter 4 to the electric motor 3 also increases.

[0048] In this way, when the load on the electric motor 3 increases due to the operation signals OS1 and OS2 input to the control device 5, the torque current supplied from the inverter 4 to the electric motor 3 increases accordingly.

[0049] In step S5 of FIG. 4, the proportional valve current value setting control by the proportional valve current control section 5C (in other words, the control device 5) is performed based on the first detection signal DS1 and the second detection signal DS2.

[0050] Here, the proportional valve current control unit 5C (in other words, the control device 5) performs proportional valve current value setting control by a first control and a second control different from the first control. Specifically, the proportional valve current control unit 5C (in other words, the control device 5) performs proportional valve current value setting control by performing table control and state transition control in parallel.

[0051] The table control corresponds to an example of a first control. The state transition control corresponds to an example of a second control. The proportional valve current control unit 5C (in other words, the control device 5) compares the proportional valve current values ​​obtained by the table control and the state transition control.

[0052] The proportional valve current value determined by table control is referred to as the first proportional valve current value. The proportional valve current value determined by state transition control is referred to as the second proportional valve current value. The proportional valve current control unit 5C (in other words, the control device 5) outputs the lower of the first and second proportional valve current values ​​as a control signal CS3 to the solenoid proportional valve 2A.

[0053] In the proportional valve current value setting control in step S5 of FIG. 4, if the converted current is judged to be abruptly fluctuating in the second detection signal DS2 during the rising stage of the torque current detected by the first detection signal DS1, the proportional valve current value is set so as to reduce the driving force of the hydraulic pump 2.

[0054] In this case, the table control uses a table (hereinafter referred to as FF table) as shown in Fig. 5. The FF table is a table in which the proportional valve current value corresponds to the torque current attainment rate (%; the degree of increase of the torque current relative to a reference value) obtained from the first detection signal DS1.

[0055] In the FF table, the proportional valve current value is set in accordance with the degree of increase in the torque current (i.e., the torque current arrival rate) so that the driving force of the hydraulic pump 2 decreases. In the illustrated FF table, a state in which the torque current arrival rate exceeds 100% is a state in which the torque current is an overcurrent.

[0056] In the illustrated example, when the torque current attainment rate is 0%, the proportional valve current value is set to a maximum value (e.g., 750 mA). Furthermore, the proportional valve current value is maintained at the maximum value until the torque current attainment rate increases to the set value (83%).

[0057] When the torque current attainment rate exceeds the set value (83%), the proportional valve current value is reduced in accordance with the degree of increase in the torque current attainment rate.

[0058] In the illustrated example, when the torque current attainment rate is 95%, the proportional valve current value is set to 700 mA. When the torque current attainment rate is 96%, the proportional valve current value is set to 550 mA. When the torque current attainment rate is 100%, the proportional valve current value is set to 500 mA. When the torque current attainment rate is 107%, the proportional valve current value is set to 400 mA. When the torque current attainment rate is 120%, the proportional valve current value is set to 200 mA. Each of the proportional valve current values ​​shown in FIG. 5 corresponds to an example of a first proportional valve current value.

[0059] On the other hand, in the state transition control, the state classification shown in Fig. 6 is determined according to the current state of the proportional valve current value setting control. The state classification refers to classification according to the setting state of the proportional valve current value. In addition, in the state transition control, the proportional valve current value is set according to the state classification and the stage of torque current increase, based on the state transition diagram shown in Fig. 7.

[0060] In the state divisions shown in Fig. 6, the state in which the proportional valve current value is set to the maximum value (maximum driving force operation) is in the "S1" division. The state in which the proportional valve current value is set to wait for a torque current decrease (proportional valve current value is not changed) is in the "S2" division. The state in which the proportional valve current value is set to monotonically increase (for example, increase by 15 mA every 0.3 seconds) is in the "S3" division. The state in which the proportional valve current value is set to constant current control is in the "S4" division. The state in which the proportional valve current value is set to monotonically decrease (for example, decrease by 15 mA every 0.3 seconds) is in the "S5" division.

[0061] The aforementioned "S1" section is a state in which the torque current is rising at the beginning of input of the operation signal. The "S2" section is a state after the torque current has risen to a certain set value. The "S3" section is a state after a sudden fluctuation is detected (described later) and the proportional valve current value is suddenly reduced. The "S4" section is a state in which the torque current has risen to a certain level and then entered a stable period. The "S5" section is a state in which an overcurrent of the torque current has suddenly occurred.

[0062] The state transition diagram shown in FIG. 7 divides the torque current increase stages according to the first detection signal DS1 into four stages: "first stage," "second stage," "third stage," and "overcurrent occurrence."

[0063] Assuming that the torque current arrival rate is T, for example, "Stage 1" is T<88%, "Stage 2" is 88%≦T<95%, "Stage 3" is 95%≦T<100%, and "Overcurrent Occurrence" is 100%≦T.

[0064] In the state transition diagram shown in FIG. 7, when the degree of increase in torque current is in the "first stage," if the setting state of the proportional valve current value is in the "S1" category (maximum proportional valve current value setting) or the "S3" category (monotonically increasing proportional valve current value), a sudden change determination is made using the second detection signal DS2.

[0065] The sudden change determination here uses the second detection signal DS2, which has a shorter detection cycle than the first detection signal DS1, to determine if the converted current is higher than a predetermined threshold and if the change per unit time of the converted current is large. Then, based on the result of the sudden change determination, the proportional valve current value is suddenly reduced.

[0066] The state transition diagram shown in FIG. 7 is characterized in that a sudden change is determined based on the second detection signal DS2 only when the setting state of the proportional valve current value is in the "S1" or "S3" category and the degree of increase in torque current is in the "first stage."

[0067] When the torque current is increasing at the "first stage" and the proportional valve current value is set to the "S1" category, a sudden increase in the torque current can easily cause the torque current to suddenly rise to the overcurrent range due to various causes. By including the sudden change determination based on the second detection signal DS2 in this category, it is possible to prevent such a sudden increase in the torque current.

[0068] Furthermore, in the illustrated state transition diagram, in the "first stage," no sudden change determination is performed except for the "S1" and "S3" stages, and the state stage is transitioned to the "S3" stage (proportional valve current value monotonically increasing). As a result, in the torque current increasing stage (i.e., the first stage), the proportional valve current value is monotonically increased, allowing the hydraulic pump 2 to exert the desired driving force.

[0069] When the degree of increase in torque current reaches the "second stage" or the "third stage," the state transition is to the "S4" stage as a basic state transition. In the "S4" stage, the proportional valve current value is stabilized within a certain range by constant current control.

[0070] Furthermore, when the torque current increases from "Stage 1" to "Stage 2" or "Stage 3" in the "S4" category state, a state transition is made to narrow the fluctuation range of the constant current control (transition from Step ±5 mA to Step -5 mA), thereby setting a more stable proportional valve current value.

[0071] Furthermore, when the degree of increase in torque current reaches the "third stage" and the previous state category is "S1," the state category is transitioned to "S2" (waiting for the motor current to decrease). At this stage, there is little chance of a sudden increase in torque current. Therefore, the output of the proportional valve current value is not changed, and the torque current corresponding to the load on the motor 3 is maintained at the current level.

[0072] When the torque current becomes an "overcurrent", this is a sudden case, and by performing the proportional valve current value setting control described above, the torque current is controlled within the range of "first stage" to "third stage".

[0073] When an "overcurrent occurs" suddenly, the state category is basically transitioned to the "S5" category (proportional valve current value monotonically decreasing) to reduce the driving force of the hydraulic pump 2. However, if the state category is already the "S5" category, the state category is transitioned to the "S4" category to stabilize the proportional valve current value.

[0074] 8 and 9 show an example of the operation of the drive control device 1 (i.e., the control device 5). T in FIG. 8 indicates the attainment rate of the torque current detected by the first detection signal DS1. R in FIG. 8 indicates the motor rotation speed. C in FIG. 8 indicates the converted current detected by the second detection signal DS2. V in FIG. 8 indicates the set proportional valve current value. FIG. 9 shows states (1) to (6) in FIG. 8 superimposed on an FF table and a state transition diagram.

[0075] When the operation signals OS1 and OS2 are input by operating the accelerator pedal 10 or the control lever 11, and the motor rotation speed R increases in accordance with the load, the torque current arrival rate T increases in the "first stage" with the passage of time. In this state, the proportional valve current value V is in the "S1" category (maximum setting: 750 mA).

[0076] When the torque current attainment rate T1 is in the "first stage" state (1), a sudden change is determined based on the second detection signal DS2. That is, in FIG. 8, the torque current attainment rate T1 is the attainment rate corresponding to the "first stage." When a sudden change in the converted current C is detected by this determination, the proportional valve current value V is reduced to 550 mA. This prevents a sudden increase in the torque current attainment rate T, and the torque current attainment rate T temporarily decreases after a slight time lag.

[0077] In the subsequent state (2), the increase in the torque current attainment rate T remains within the "first stage," so the setting of the proportional valve current value V transitions from the "S1" category to the "S3" category, as shown in the state transition diagram of FIG. 9. As a result, the proportional valve current value V increases monotonically. During this time, the torque current attainment rate T, which had temporarily decreased, increases with the increase in the motor rotation speed R and the proportional valve current, as shown in FIG. 8.

[0078] In state (3) after the proportional valve current value V has monotonically increased, the torque current arrival rate T3 at that time is included in the "second stage," so the setting of the proportional valve current value V transitions to the "S4" section, as shown in the state transition diagram of Fig. 9. As a result, the proportional valve current value V is subsequently controlled to a constant current and reaches a stable state.

[0079] Then, in the subsequent state (4), the torque current attainment rate T4 at that time has risen to the "third stage" (96%). Therefore, the state transitions to the "S4" state (constant current control) in the state transition diagram shown in FIG. 7. At this time, the set value in the FF table decreases as shown in FIG. 9, so the FF table is selected and the proportional valve current value V decreases to approximately 540 mA.

[0080] In the subsequent state (5), the torque current attainment rate T5 at that time has fallen to the “first stage,” and as shown in the state transition diagram of FIG. 9 , the setting of the proportional valve current value V transitions to the “S3” category, and the proportional valve current value V is monotonically increased.

[0081] In the subsequent state (6), the torque current arrival rate T6 at that time has reached the “second stage,” so the setting of the proportional valve current value V transitions from the “S3” category to the “S4” category, and the proportional valve current value V is stabilized by constant current control.

[0082] As described above, the drive control device 1 according to an embodiment of the present invention detects a sudden fluctuation in the converted current (the current supplied to the inverter 4) using the second detection signal DS2, which has a shorter detection cycle than the first detection signal DS1 based on the torque current, and controls the driving force of the hydraulic pump 2 so that the torque current does not become an overcurrent. This makes it possible to detect a sudden fluctuation that cannot be detected by detecting the torque current alone, and to prevent the torque current from becoming an overcurrent. This makes it possible, in drive control of a crawler crane or the like, to avoid a situation in which the protection circuit of the inverter 4 is activated and the actuator stops during operation, thereby ensuring the safety and continuity of the operation.

[0083] Furthermore, according to the drive control device 1, when the torque current is increasing, a sudden change in the converted current is determined using the second detection signal DS2, and the drive force is reduced when a sudden change is detected, thereby effectively suppressing sudden increases in the torque current. Once the torque current has increased to a certain level, the proportional valve current value is stabilized without reducing the drive force, so that an appropriate drive force can be maintained in response to an increase in the load.

[0084] Furthermore, the drive control device 1 sets a proportional valve current value to be input to the electromagnetic proportional valve for controlling the drive force when controlling the drive force of the hydraulic pump 2. In this setting, table control and state transition control are performed in parallel. The proportional valve current values ​​determined by each control are then compared, and the electromagnetic proportional valve is controlled by the lower proportional valve current value. This allows the risk of a large increase in torque current to be doubly suppressed by both table control and state transition control, improving the reliability of risk management.

[0085] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configurations are not limited to these embodiments, and the present invention also includes design changes within the scope of the present invention. Furthermore, the above-described embodiments can be combined by utilizing each other's technologies as long as there are no particular contradictions or problems in their purposes, configurations, etc.

[0086] The disclosures of the specification, drawings, and abstract contained in Japanese Patent Application No. 2024-146634, filed on August 28, 2024, are incorporated herein by reference in their entirety.

[0087] The present invention can be applied to hydraulic pumps that supply pressure oil to various actuators.

[0088] REFERENCE SIGNS LIST 1 Drive control device 2 Hydraulic pump 2A Solenoid proportional valve 3 Electric motor 4 Inverter 4A Current detection unit 5 Control device 5A Actuator control unit 5B Electric motor rotation speed control unit 5C Proportional valve current control unit 6 Control valve 6A to 6F Hydraulic motor 7 Commercial power supply 8 High-voltage start panel 10 Accelerator pedal 11 Operation lever 100 Crawler crane 101, 102 Traveling body 103 Swing device 104 Swing body 105 Boom 110, 111, 112, 113 Sheave 115 Main hoisting rope 116 Auxiliary hoisting rope 117 Bucket 118 Pendant rope 119 Hoisting rope 120 Cab OS1, OS2 Operation signal CS1, CS2, CS3 Control signal DS1 First detection signal DS2 Second detection signal

Claims

1. A drive control device for an electric hydraulic pump that is driven by an electric motor and controls a hydraulic pump that discharges pressurized oil to drive an actuator, comprising: an inverter that receives an input current and outputs a torque current to the electric motor according to the load on the electric motor; and a control device that controls the hydraulic pump and the inverter, wherein the control device controls the hydraulic pump based on a detection signal based on the input current and a detection signal based on the torque current so that the torque current does not become an overcurrent.

2. A drive control device for an electric hydraulic pump according to claim 1, wherein the detection period of the detection signal based on the input current is shorter than the detection period of the detection signal based on the torque current.

3. A drive control device for an electric hydraulic pump according to claim 1, wherein the hydraulic pump is a variable displacement pump, and the control device changes the discharge capacity of the hydraulic pump by setting a proportional valve current value of an electromagnetic proportional valve.

4. A drive control device for an electric hydraulic pump according to claim 3, wherein the control device sets the proportional valve current value so that the driving force of the hydraulic pump decreases according to the degree of increase in the torque current.

5. A drive control device for an electric hydraulic pump as described in claim 3, wherein the control device sets the proportional valve current value so as to reduce the driving force of the hydraulic pump when it determines that there is a sudden fluctuation in the detection signal based on the input current during the torque current increase stage.

6. A drive control device for an electric hydraulic pump according to claim 3, wherein the control device performs state transition control by defining stage divisions into which the torque current increase stages are divided and state divisions of the proportional valve current value set for each of the stage divisions.

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