JP2022153098A - Construction machine - Google Patents

Abstract

To shorten execution time of warm-up operation and, as a result, shorten charging time of a power storage device.SOLUTION: The construction machine includes an electric motor that drives a hydraulic pump, a power storage device that supplies electric power to the electric motor, a charger that charges the power storage device, and a control device that controls the charger. Based on at least a temperature of the power storage device, the control device determines whether to perform a warm-up operation in which charging and discharging of the power storage device are repeated. Then, the control device performs warm-up operation by changing the magnitude of a charging current and a discharging current during warm-up operation according to a relation between the temperature of the power storage device and a charging rate of the charger.SELECTED DRAWING: Figure 6

Description

The present invention relates to construction machinery.

In recent years, the electrification of automobiles has been rapidly progressing from the viewpoint of curbing global warming, and the electrification of construction machinery has also started to progress mainly in Europe. As a power source for an electric motor, which is a driving source that enables electrification, a power storage device is mainly used as in automobiles.

Since electric construction machines are used in a harsh environment exposed to the open air, power storage devices are greatly affected by the external environment. In order to supply power from the power storage device to the electric motor, it is necessary to store power in advance in the power storage device.

The allowable current value that can flow through the power storage device is limited by the characteristics of the power storage device, and this allowable current value is further reduced at low temperatures. Since a sufficient current value cannot flow during charging, there is a problem that the charging time becomes long. Therefore, warm-up operation for warming the power storage device is performed to increase the allowable current value, thereby shortening the charging time. Warm-up operation is performed, for example, by intentionally repeating charging and discharging of the power storage device. The power storage device can be warmed by the heat generated by the charge/discharge current during warm-up operation (see, for example, Patent Documents 1 and 2).

However, in the prior art, it is only necessary to determine whether or not to perform warm-up operation according to the detected temperature, and it is not possible to sufficiently shorten the execution time of warm-up operation.

JP 2015-094173 A JP 2013-052866 A

The present invention provides a construction machine capable of shortening the execution time of warm-up operation and, as a result, shortening the charging time of a power storage device.

In order to solve the above problems, a construction machine according to the present invention provides an electric motor that drives a hydraulic pump, an electric storage device that supplies electric power to the electric motor, a charger that charges the electric storage device, and a controller that controls the charger. and a control device. Based on at least the temperature of the power storage device, the control device determines whether or not to perform a warm-up operation in which charging and discharging of the power storage device are repeated. Then, the control device performs the warm-up operation by changing the magnitude of the charging current and the discharging current during the warm-up operation according to the relationship between the temperature of the power storage device and the charging rate of the charger. .

ADVANTAGE OF THE INVENTION According to this invention, the construction machine which can shorten the execution time of a warm-up operation and, as a result, can shorten the charging time of an electrical storage apparatus can be provided.

1 is an external configuration diagram of a construction machine 10 according to an embodiment; FIG. 2 is a block diagram illustrating a configuration example of an electric motor that drives a hydraulic control device and an electric system that supplies electric power to the electric motor provided in the construction machine 10. FIG. 4 is a graph illustrating the relationship between the state of charge (SOC) and the allowable current when the power storage device 4 is charged. 4 is a graph illustrating the relationship between the state of charge (SOC) and the allowable current when the power storage device 4 is discharged. An example of a table provided in the controller 6 is shown. 4 is a flowchart for explaining warm-up operation in the construction machine of the embodiment; 7 is a graph for explaining warm-up operation in the construction machine of the embodiment;

Hereinafter, this embodiment will be described with reference to the accompanying drawings. In the accompanying drawings, functionally identical elements may be labeled with the same numbers. It should be noted that although the attached drawings show embodiments and implementation examples in accordance with the principles of the present disclosure, they are for the purpose of understanding the present disclosure and are in no way used to interpret the present disclosure in a restrictive manner. is not. The description herein is merely exemplary and is not intended to limit the scope or application of this disclosure in any way.

Although the present embodiments are described in sufficient detail to enable those skilled in the art to practice the present disclosure, other implementations and configurations are possible without departing from the scope and spirit of the present disclosure. It is necessary to understand that it is possible to change the composition/structure and replace various elements. Therefore, the following description should not be construed as being limited to this.

As shown in the external structural view of FIG. 1, the construction machine 10 of the present embodiment is, for example, a hydraulic excavator, and includes, for example, an upper revolving body 1110, a lower traveling body 1120, a working machine 1130, and a revolving mechanism 1140. , and a cylinder 1160 .

The upper revolving structure 1110 is a part of the vehicle body that is rotatably attached to the upper part of the lower traveling structure 1120 via a revolving mechanism 1140, and is equipped with an operator's cab 1111 for operation by an operator. The driver's cab 1111 is equipped with a door D that can be opened and closed to separate the driver's cab 1111 from the outside. The door D is configured to be lockable with a physical key.

The upper revolving body 1110 revolves with respect to the lower running body 1120 about a rotation axis parallel to the height direction of the construction machine 10 . The upper swing structure 1110 houses, for example, a hydraulic pump and a hydraulic controller. The undercarriage 1120 includes crawler belts 1121 driven by, for example, a hydraulic pump (not shown), and causes the construction machine 10 to travel under the control of the control device. As will be described later, the construction machine 10 also incorporates an electric motor that drives the hydraulic control device, a power storage device that supplies electric power to the electric motor, and other electrical systems.

The work machine 1130 is provided, for example, in the front portion of the upper revolving body 1110 and is driven by a cylinder 1160 to perform work such as excavation work. Work implement 1130 has, for example, boom 1131 , arm 1132 , and bucket 1133 . The revolving mechanism 1140 has a hydraulic motor (not shown), and rotates the upper revolving body 1110 with respect to the lower traveling body 1120 around a rotation axis parallel to the height direction of the construction machine 10 under the control of the hydraulic control device. to rotate.

The construction machine 10 generally uses a hydraulic pump or the like to power various moving parts. Such a hydraulic pump or the like is connected to an electric motor, the hydraulic pump is rotated by power from the electric motor to generate pressure, and the opening/closing degree of the solenoid of the hydraulic valve is adjusted to operate various movable parts. The degree of opening and closing of the solenoid can be controlled by a control lever or pedal on the driver's seat.

With reference to the block diagram of FIG. 2, a configuration example of an electric motor that drives the hydraulic control device and an electric system that supplies electric power to the electric motor provided in the construction machine 10 will be described. In FIG. 2 , power lines for supplying power are indicated by solid lines, and communication signal lines for transmitting and receiving control signals and the like are indicated by dotted lines.

This construction machine 10 includes an electric motor 2 that drives a hydraulic control device 1, an inverter 3 that controls the electric motor 2, and a high-voltage power storage device 4 that supplies electric power to the electric motor 2 via the inverter 3. and a charger 5 for charging the power storage device 4 for high voltage. Also, a controller 6 (control device) is provided for controlling these devices and for controlling, monitoring and protecting the entire operation of the electric system. Furthermore, a junction box 9 is provided for electrically connecting these devices. The junction box 9 provides dustproof and waterproof functions for connection of various devices, and is provided with OCP (Overcurrent protection) such as relays and fuses from the viewpoint of protection against misuse and failure.

As described above, there is a limit to the allowable current value that can flow through the power storage device 4, and the allowable current (discharge current, charge current) value is further reduced at low temperatures. Therefore, power storage device 4 of the present embodiment is configured to be able to perform warm-up operation by repeatedly performing charging and discharging when the temperature is low. Controller 6 determines whether or not to perform warm-up operation based on the temperature of power storage device 4 . It should be noted that the necessity of execution of the warm-up operation may be determined in consideration of not only the temperature of the power storage device 4 but also other determination factors. As will be described later, the value of the discharge current of the charge current during warm-up operation is appropriately updated according to changes in the situation.

A power conversion device 7 is connected to the power storage device 4 via a junction box 9 . The power conversion device 7 converts the voltage supplied from the power storage device 4 to generate a control voltage for each device. A low-voltage (for example, 12/24V) power storage device 8 is connected to the power conversion device 7 .

A low-voltage power storage device 8 generates a control voltage for controlling each device. Various warning lights are installed on the construction machine 10 . A power storage device 8 is provided as a power storage device for supplying a low voltage used in such warning lights and the like.

Inverter 3 converts the DC power output from power storage device 4 into AC power in order to control motor 2 at an arbitrary number of revolutions. In order for the power storage device 4 to supply power, it is necessary to store power in advance. The charger 5 is connected to system power supply equipment and charges the power storage device 4 under the control of the controller 6 .

Inside the power storage device 4, a current sensor 11 as a current measuring unit for measuring the current flowing through the power storage device 4, a voltage sensor 12 as a voltage measuring unit for measuring the voltage of each battery cell constituting the power storage device 4, and , a temperature sensor 13 as a temperature measuring unit for measuring the temperature of each battery cell of the power storage device 4 is attached.

A plurality of each of the various sensors 11 to 13 may be provided in one power storage device 4 . When a plurality of sensors of the same type are provided in one power storage device 8, the measured values can be output as an average value, maximum value, minimum value, intermediate value, or the like. The controller 6 calculates the power storage amount of the power storage device 8 according to the current, voltage, temperature, etc. measured by the various sensors 11 to 13, and further calculates the state of charge (SOC) from the power storage amount.

The relationship between the charging rate (SOC) and the allowable current during charging and discharging of the power storage device 4 will be described with reference to FIGS. 3 and 4. FIG. The allowable current means a current that can be supplied by power storage device 4 under certain conditions.

As shown in FIGS. 3 and 4, when the power storage device 4 is at a high temperature, the permissible charging current and the permissible discharging current are larger than those at a low temperature.

Further, as shown in FIGS. 3 and 4, when the power storage device 4 is at a low temperature, the higher the charging rate (SOC), the higher the allowable discharge current. On the other hand, as shown in FIG. 3, when the power storage device 4 is at a low temperature, the increase in the allowable charging current is very small with respect to the increase in the state of charge (SOC). Considering that heat generation can be promoted by applying a large current, when charging and discharging are performed as a warm-up operation of the power storage device 4, the temperature may be raised to about room temperature (up to about 25° C.). Desirably, the state of charge (SOC) should be kept high.

As can be seen from FIGS. 3 and 4 , the allowable current during charging and discharging of the power storage device 4 varies depending on the state of charge (SOC) of the power storage device 4 and the temperature of the power storage device 4 . Therefore, in the present embodiment, the charging current value x and the discharging current value y during the warm-up operation are determined according to the combination of the state of charge (SOC) of the power storage device 4 and the temperature T of the power storage device 4. The warm-up operation of the power storage device 4 is controlled according to the determined values x and y. The controller 6 sequentially calculates or measures the charging rate SOC and the temperature T, sets the charging current and discharging current suitable for the calculated or measured charging rate (SOC) and temperature T, and performs warm-up operation.

As an example, the controller 6 has a table for determining the charging current values x, y during warm-up, as shown in FIG. This table stores the charging current value x and the discharging current value y during warm-up operation for each combination of the charging rate (SOC) of the power storage device 4 and the temperature T of the power storage device. The controller 6 refers to the table based on the calculated state of charge (SOC) and the measured temperature T of the power storage device 4, determines the value x of the charging current and the value y of the discharging current, and controls the warm-up operation. do. Note that the discharge power based on the discharge current during warm-up operation can be regenerated to the power supply that supplies charging power to the charger 5 .

In the table of FIG. 5, for each combination of the charging rate (SOC) and the temperature T, the charging current value x (x11, x12, . . . x99) and the discharging current value y (y11, y12, . y99), but in any combination, the value of the charging current x is set to a value greater than the value of the discharging current y. The values of x and y are appropriately updated during warm-up, but the relationship x>y is always maintained according to the stored values in the table of FIG. By maintaining the relationship of x>y during warm-up operation, the state of charge (SOC) increases monotonically during warm-up operation. The higher the charging rate (SOC), the larger the allowable current, and accordingly the values of x and y can be set to larger values. Therefore, maintaining the relationship x>y is preferable for shortening the charging time of the power storage device 4 . However, depending on the operating conditions, a time period where x≦y may be partially set.

In the table of FIG. 5, the values of x and y are preferably set so that the ratio of the charging current value x to the discharging current value y increases as the state of charge (SOC) increases. As a result, the ratio of the charging current to the discharging current during warm-up operation is increased as the state of charge (SOC) increases, so that the charging time of power storage device 4 can be shortened. In the table of FIG. 5, the values of x and y are preferably set so that the ratio of the charging current value x to the discharging current value y increases as the temperature T rises. As a result, the ratio of the charging current to the discharging current during warm-up operation is increased as the temperature T rises, so that the charging time of power storage device 4 can be shortened.

The warm-up operation of the construction machine 10 according to the embodiment will be described with reference to the flowchart of FIG. 6 and the graph of FIG.

First, in step S10, temperature T of power storage device 4 is detected. Then, in step S11, it is determined whether or not the detected temperature T is lower than the threshold temperature Tth at which warm-up operation is required. In the case of T<Tth, it is determined that warm-up operation is necessary, the process proceeds to step S12, and preparation for warm-up operation is started. If T≧Tth, it is determined that warm-up operation is unnecessary, and normal operation (charging) is performed (step S24).

In subsequent step S12, based on the measured values of the current sensor 11 and the voltage sensor 12, the amount of electricity stored in the electricity storage device 4 is calculated, and the state of charge (SOC) is also calculated. The controller 6 refers to the table of FIG. 5 based on the measured temperature T and the calculated state of charge (SOC), and determines the conditions (conditions 1 to 5) of the charge and discharge current during warm-up operation. The charging current value x and the discharging current value y are set (or updated) (step S13), and warm-up operation is performed (step S14).

As shown in FIG. 7, warm-up operation is started at time t0, and charging and discharging of power storage device 4 are repeated in a short period of time during warm-up operation according to the determined charging current and discharging current values. The top graph in FIG. 7 shows changes over time in the charge/discharge current to the power storage device 4, with the discharge current on the positive side and the charging current on the negative side. The graph in the middle of FIG. 7 shows the change over time of the state of charge (SOC). The charge rate (SOC) also repeats increase and decrease due to repetition of charging and discharging by warm-up operation. However, since the value of the charging current x is set to a value larger than the value of the discharging current y in principle, the charging rate (SOC) also increases with time as a whole. In FIG. 7, conditions 1 to 5 include the charging current value x and the discharging current y value set by referring to the table shown in FIG. 5 according to the state of charge (SOC) and temperature T. It shows the conditions for executing warm-up operation. The contents of conditions 1 to 5 change according to changes in the situation. FIG. 7 shows an example in which conditions 1 to 5 are set, but the number of conditions set (updated) during warm-up operation is not limited to this.

Returning to the flowchart of FIG. 6, the temperature T and the state of charge (SOC) of the power storage device 4 are detected or calculated at predetermined time intervals after the warm-up operation is started according to the set conditions (step S20). , S21).

In subsequent step S22, it is determined whether the temperature T detected in step S21 has exceeded the next target temperature Tg (Tg1, Tg2, . . . ). If T>Tg, unless the temperature T has reached the final target temperature Tmax (No in step S23), the process returns to step S13, and the charging/discharging current conditions are updated based on the table of FIG. It should be noted that if the determination in step S23 is Yes, the warm-up operation ends and the operation is switched to normal operation, that is, normal charging operation to the power storage device 4 .

If it is determined in step S22 that T≤Tg, in step S32 it is determined whether or not the charging rate (SOC) calculated in step S21 exceeds the next target charging rate SOC (SOC1, SOC2...). be judged. If Yes, the process proceeds to step S33. If No, the process returns to step S14 and the warm-up operation is continued under the same charging/discharging conditions.

In step S33, it is determined whether or not the charging rate (SOC) has reached the final target charging rate SOCmax. If not reached (No in step S33), the process returns to step S13, and the charging/discharging current conditions are updated based on the table. If Yes is determined in step S33, it is determined that the charging is completed, and the charging operation is terminated.

As described above, according to the present embodiment, the state of charge (SOC) and the temperature T are continuously calculated or measured even after the warm-up operation is started, and the state of charge (SOC) and the temperature T are calculated or measured. The value x of the charging current and the value y of the discharging current are determined according to the combination, and the conditions for warm-up operation are appropriately updated. As a result, the warm-up operation is performed under optimum conditions, and the operation of charging power storage device 4 can be completed in a shorter period of time.

The present invention is not limited to the above-described embodiments, and includes various modifications other than those described above. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration.

DESCRIPTION OF SYMBOLS 1...Hydraulic control apparatus 2...Electric motor 3...Inverter 4...Power storage device 5...Charger 6...Controller 7...Power conversion device 8...Power storage device 9...Junction box 10...Construction machine 11 Current sensor 12 Voltage sensor 13 Temperature sensor 1110 Upper revolving body 1111 Cab 1120 Undercarriage 1121 Crawler 1130 Working machine 1131 Boom 1132 Arm 1133 Bucket, 1140... Turning mechanism, 1160... Cylinder.

Claims (8)

an electric motor that drives the hydraulic control device;
a power storage device that supplies power to the electric motor;
a charger that charges the power storage device;
and a control device that controls the charger,
The control device is
determining whether or not to perform a warm-up operation in which charging and discharging of the power storage device are repeated based on at least the temperature of the power storage device;
The construction machine, wherein the warm-up operation is performed by changing the magnitude of charging current and discharging current during the warm-up operation according to the relationship between the temperature of the power storage device and the charging rate of the charger. . 2. The construction machine according to claim 1, wherein said controller sets said charging current to a value greater than said discharging current during said warm-up operation. 2. The construction machine according to claim 1, wherein said controller increases the ratio of said charging current to said discharging current as the temperature of said power storage device increases during said warm-up operation. 2. The construction machine according to claim 1, wherein during said warm-up operation, said control device increases the ratio of said charging current to said discharging current as the charging rate of said power storage device increases. The control device sets the charging current to a value larger than the discharging current in the warm-up operation,
increasing the ratio of the charging current to the discharging current as the temperature of the power storage device increases;
The construction machine according to claim 1, wherein the ratio of said charging current to said discharging current is increased as the charging rate of said power storage device increases. The control device includes a table storing the charging current value and the discharging current value for each combination of the temperature of the power storage device and the charging rate,
2. The construction machine according to claim 1, wherein said control device refers to said table and determines the value of said charging current and said value of said discharging current based on said obtained temperature and said charging rate. After setting the charging current and the discharging current for the warm-up operation, the control device sets the charging current and the discharging current based on the newly measured or calculated temperature and the charging rate. The construction machine according to claim 1, wherein the conditions for warm-up operation are updated. 2. The construction machine according to claim 1, wherein said power storage device regenerates discharged power based on a discharged current during said warm-up operation to a power supply that supplies power to said charger.

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