Electric construction machinery

Abstract

To provide an electric construction machine capable of preventing failure in an electric circuit of a lithium ion battery or peripheral equipment when a vehicle body falls over.SOLUTION: An electric construction machine comprises an inclination sensor 31 that detects an inclination angle of a traveling body 1 or a revolving body 2, a cutoff relay 23 that connects or cuts off a lithium ion battery 20 and an inverter 22, and a controller 30 that switches the cutoff relay 23 so that a power supply circuit 21 connecting the lithium ion battery 20 and the inverter 22 is cut off when the value of the inclination sensor 31 exceeds a predetermined threshold value.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to electric construction machines such as hydraulic excavators.

Background Art

[0002] The environment in which construction machines are operated includes slopes and unstable scaffolds, and there is a possibility that the machines may tip over. Although there are means to notify the operator of the possibility of tipping over, there are cases where the operator cannot respond and the machine still tips over. Therefore, measures to prevent serious consequences even if the machine tips over are also important. For example, in Patent Document 1, the lithium-ion battery of an electric construction machine is surrounded by a protective structure to prevent damage due to the impact during tipping over.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, it is not recommended to continuously use a lithium-ion battery used in an electric construction machine in an extremely tilted state. According to the measure of Patent Document 1, although physical damage (such as trauma) of the lithium-ion battery due to the impact during tipping over can be prevented, when the power supply to the lithium-ion battery continues in a state where the vehicle body has tipped over, there is a possibility of an electrical circuit failure in the lithium-ion battery or peripheral devices.

[0005] An object of the present invention is to provide an electric construction machine capable of preventing an electrical circuit failure in a lithium-ion battery or peripheral devices when the vehicle body tips over.

Means for Solving the Problems

[0006] To achieve the above objective, the present invention provides an electric construction machine comprising: a traveling body; a slewing body rotatably attached to the traveling body and constituting a vehicle body together with the traveling body; a working device rotatably attached to the slewing body; a plurality of actuators for driving the traveling body, the slewing body, and the working device; a hydraulic pump for supplying hydraulic fluid to the plurality of actuators; an electric motor for driving the hydraulic pump; a lithium-ion battery; and an inverter connected to the lithium-ion battery via a power supply circuit for converting the DC power of the lithium-ion battery into AC power and supplying it to the electric motor, wherein the electric construction machine further comprises: a tilt sensor for detecting the tilt angle of the traveling body or the slewing body; a shut-off relay for conducting or shutting off the power supply circuit; and a controller for switching the shut-off relay so that the power supply circuit is shut off when the value of the tilt sensor exceeds a predetermined first threshold.

[0007] According to the present invention configured as described above, when the vehicle or turning body is tilted significantly, the power supply circuit connecting the lithium-ion battery and the inverter is shut off, making it possible to prevent failure of the lithium-ion battery or the electrical circuits of peripheral equipment due to continued power supply while the vehicle is overturned. [Effects of the Invention]

[0008] According to the electric construction machine of the present invention, it is possible to prevent failures in the electrical circuits of the lithium-ion battery or peripheral equipment caused by continuing to supply power to the lithium-ion battery when the vehicle body is overturned. [Brief explanation of the drawing]

[0009] [Figure 1] External view of a hydraulic excavator in an embodiment of the present invention [Figure 2] Configuration diagram of a hydraulic system in an embodiment of the present invention [Figure 3] Electrical circuit diagram of a power system in an embodiment of the present invention [Figure 4]State transition diagram of the vehicle body related to the storage of the reference inclination angle in an embodiment of the present invention [Figure 5] State transition diagram of a lithium-ion battery in an embodiment of the present invention. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments of the electric construction machinery according to the present invention will be described with reference to the drawings, using a hydraulic excavator as an example. In each figure, equivalent elements are denoted by the same reference numerals, and redundant explanations will be omitted as appropriate.

[0011] Figure 1 is an external view of a hydraulic excavator according to the present invention. In Figure 1, the hydraulic excavator comprises a traveling body 1, a slewing body 2 that is rotatably mounted on the traveling body 1 and forms the vehicle body together with the traveling body 1, and a working device 3 that is rotatably mounted on the front side of the slewing body 2. The slewing body 2 is driven by a slewing motor (not shown).

[0012] The work device 3 has a boom 4 that is rotatably connected to the slewing body 2 in the vertical direction, and an arm 5 that is rotatably connected to the tip of the boom 4 in the vertical direction. An attachment (a bucket 6 in this embodiment) is rotatably connected to the tip of the arm 5 depending on the work to be performed. The boom 4 is driven by a boom cylinder 7, the arm 5 is driven by an arm cylinder 8, and the bucket 6 is driven by a bucket cylinder 9. The traveling body 1 has a left crawler 10a, a right crawler 10b, a left travel motor 11a that rotates the left crawler 10a, and a right travel motor 11b that rotates the right crawler 10b (shown in Figure 2). The traveling body 1 can move forward or backward or turn by independently changing the rotation direction of the left crawler 10a and the right crawler 10b.

[0013] Figure 2 is a diagram of the hydraulic system installed in the hydraulic excavator shown in Figure 1. Power generated by the electric motor 12 drives the gear pump 13 and the main pump 14. The gear pump 13 supplies hydraulic pressure to the pilot valve 15. The pilot valve 15 reduces the hydraulic pressure supplied from the gear pump 13 in response to the operator's operation, generating pilot pressure that is input to the control valve 16. The main pump 14 supplies hydraulic pressure to the control valve 16. The control valve 16 supplies hydraulic pressure to the actuators (boom cylinder 7, arm cylinder 8, bucket cylinder 9, left travel motor 11a, right travel motor 11b, and slewing motor) in response to the pilot pressure input from the pilot valve 15. As the actuators operate, the boom 4, arm 5, bucket 6, left crawler 10a, and right crawler 10b move, causing the slewing body 2 to rotate.

[0014] Figure 3 is an electrical circuit diagram of the power system mounted on the hydraulic excavator shown in Figure 1. The lithium-ion battery 20 is connected to the inverter 22 via the power supply circuit 21. The power supply circuit 21 is equipped with a tripping relay 23. The switch-side circuit 23a of the tripping relay 23 is connected to the lithium-ion battery 20, and the normally closed-side contact 23b is connected to the inverter 22. The inverter 22 converts the DC power from the lithium-ion battery 20 into AC power necessary to rotate the electric motor 12 at the desired rotational speed and supplies it to the electric motor 12.

[0015] The lead-acid battery 24 is connected to the B terminal of the key switch 25. The key switch 25 can be switched to three positions: OFF, KEY_ON, and START. When in the OFF position, the B terminal is not connected to either the K terminal or the S terminal. When in the KEY_ON position, the B terminal is connected only to the K terminal. When in the START position, the B terminal is connected to both the K terminal and the S terminal. The K terminal of the key switch 25 is connected to the controller 30, and the S terminal is connected to the inverter 22. When the inverter 22 recognizes that the key switch 25 is in the START position, it operates the electric motor 12. The controller 30 has a processing unit such as a CPU, a storage device such as memory 30a, an input terminal 30b for receiving signals from external devices, and an output terminal 30c for outputting signals to external devices.

[0016] The input terminal 30b of the controller 30 is connected to a tilt sensor 31 for measuring the tilt angle (roll angle, pitch angle) of the slewing body 2 with respect to the horizontal plane, a left travel pilot pressure sensor 32a for measuring the pilot pressure of the left travel motor 11a, a right travel pilot pressure sensor 32b for measuring the travel pilot pressure of the right travel motor 11b, a boom rod pressure sensor 33 for measuring the rod-side pressure of the boom cylinder 7, a left travel drive pressure sensor 34a for measuring the drive pressure of the left travel motor 11a, and a right travel drive pressure sensor 34b for measuring the drive pressure of the right travel motor 11b.

[0017] The output terminal 30c of the controller 30 is connected to the coil-side circuit 36a of the self-holding relay 36 via a protection diode 35. The switch-side circuit 36b of the self-holding relay 36 is connected to the lead-acid battery 24, and the other end joins a circuit that goes to the coil-side circuit 36a of the self-holding relay 36 via the coil-side circuit 36a of the tripping relay 23 and the release switch 37. The release switch 37 is an alternate-type push-button switch.

[0018] The controller 30 is powered by the lead-acid battery 24 and starts up when the key switch 25 is switched to the KEY_ON position. At this time, the output terminal 30c is in the LOW state and the self-holding relay 36 is in the open state.

[0019] When the conditions described below are satisfied, the controller 30 sets the output terminal 30c to HIGH and applies a voltage to the coil side circuit 36a of the self - holding relay 36. The switch side circuit 36b of the self - holding relay 36 conducts, and a voltage from the lead - acid battery 24 is applied to the coil side circuit 23c of the cutoff relay 23. The switch side circuit 23a of the cutoff relay 23 switches to the normally - open side contact 23d. As a result, the power supply to the inverter 22 stops, and the lithium - ion battery 20 is disconnected from the circuit. Also, even when the voltage application from the controller 30 stops, the self - holding relay 36 maintains the state where the switch side circuit 36b is closed by the self - holding circuit. When the release switch 29 is pressed in this state, the self - holding is released, and the switch side circuit 36b becomes open. A signal indicating the state of the release switch 37 is also input to the controller 30.

[0020] The controller 30 stores the value of the tilt sensor 31 immediately after the operator operates the key switch 25 to the KEY_ON position or immediately after the vehicle body stops running as the reference tilt angle B. Immediately after the operator operates the key switch 25 to the KEY_ON position or immediately after the vehicle body stops running, the vehicle body is in a relatively stable place and has not fallen. That is, the reference tilt angle B is the tilt angle when the vehicle body has not fallen, and is used as one of the criteria for determining whether the vehicle body has fallen later.

[0021] FIG. 4 is a state transition diagram of the vehicle body related to the storage of the reference tilt angle B. When the key switch 25 is operated to the KEY_ON position in the system stop state, the controller 30 starts up and transitions to the running stop state. The controller 30 stores the value of the tilt sensor 31 as the reference tilt angle B immediately after startup (step S101).

[0022] When the vehicle is stopped, the controller 30 determines whether the value of the left drive pressure sensor 34a or the right drive pressure sensor 34b is greater than or equal to a predetermined threshold E (step S102). The threshold E is the minimum drive pressure of the left drive motor 11a and the right drive motor 11b during driving. If the result of the determination in step S102 is NO, the vehicle remains in the stopped state, and if the result of the determination in step S102 is also NO, the vehicle transitions to the driving state.

[0023] In the driving state, the controller 30 determines whether the values ​​of the left drive pressure sensor 34a and the right drive pressure sensor 34b are below a predetermined threshold F (step S103). The threshold F is the maximum drive pressure of the left motor 11a and the right motor 11b when driving and when driving is stopped. If the result of the determination in step S103 is NO, the driving state is maintained, and if the result of the determination in step S103 is NO, the value of the tilt sensor 31 is stored as the reference tilt angle B (step S104), and the system transitions to the stopped state.

[0024] Figure 5 is a state transition diagram of the lithium-ion battery 20. When the lithium-ion battery 20 is in a state where it can be energized, the controller 30 determines whether the value of the tilt sensor 31 is greater than a predetermined threshold A (step S201). Threshold A is the tilt angle at which the vehicle body can be considered to have clearly overturned, regardless of the posture of the work device 3 or the rotation angle of the slewing body 2.

[0025] If the result of step S201 is YES, output terminal 30c is set to HIGH (step S202). As a result, if the vehicle is clearly overturned, the shut-off relay 23 is unconditionally turned ON, and the lithium-ion battery 20 becomes unpowered.

[0026] If the result of step S201 is NO, it is determined whether the value of the left driving pilot pressure sensor 32a or the right driving pilot pressure sensor 32b is greater than or equal to a predetermined threshold C (step S203). The threshold C is the minimum pilot pressure required for the left driving motor 11a or the right driving motor 11b to start moving.

[0027] If the result of step S203 is YES, it is determined whether the left drive pressure sensor 34a and the right drive pressure sensor 34b are below a predetermined threshold D (step S204). The threshold D is smaller than the minimum drive pressure (= threshold E) of the left drive motor 11a (or right drive motor 11b) required for normal driving, and slightly larger than the drive pressure of the left drive motor 11a (or right drive motor 11b) when the vehicle body 1 is lifted and the left crawler 10a (or right crawler 10b) is running freely.

[0028] If the result of step S204 is NO, the lithium-ion battery 20 is kept in a state where it can be energized. That is, as long as at least one of the left crawler 10a and the right crawler 10b is not spinning freely, the shut-off relay 23 will not switch to ON, and the lithium-ion battery 20 will remain in a state where it can be energized. As a result, if the vehicle moves to a place with a different slope due to driving, it will not be considered to have overturned, and the lithium-ion battery 20 can be used continuously.

[0029] If the result of step S204 is YES, it is determined whether or not the vehicle body is jacked up. Specifically, it is determined whether or not the value of the boom rod pressure sensor 33 is below a predetermined threshold (0 MPa) (step S205). Jacking up is mainly performed by lowering the boom 4, at which time pressure is generated on the rod side of the boom cylinder 7. On the other hand, when the working device 3 is suspended in the air, no pressure is generated on the rod side of the boom cylinder 7 due to gravity. In this embodiment, the threshold is set to 0 MPa, but if pressure is generated on the rod side of the boom cylinder 7 even when the working device 3 is suspended in the air due to the characteristics of the hydraulic circuit, the threshold is set to a value greater than that pressure.

[0030] If the result of step S205 is NO, the lithium-ion battery 20 remains in a state where it can be energized. As a result, even if the left crawler 10a or the right crawler 10b spins freely while the vehicle is jacked up, it is not considered a rollover, and the lithium-ion battery 20 can be used continuously.

[0031] If the result of step S205 is YES, output terminal 30c is set to HIGH (step S202). As a result, if the crawler on the operating side slips even though the vehicle body is not jacked up (for example, if the vehicle overturns while driving), the shut-off relay 23 turns ON, and the lithium-ion battery 20 becomes unpowered.

[0032] If the result of step S203 is NO, it is determined whether the value of the tilt sensor 31 has changed from the reference tilt angle B (step S206). Specifically, if the difference between the value of the tilt sensor 31 and the reference tilt angle B exceeds a predetermined threshold (for example, the detection accuracy of the tilt sensor 31), it is determined that the value of the tilt sensor 31 has changed from the reference tilt angle B.

[0033] If the result of step S206 is NO, the lithium-ion battery 20 is kept in a state where it can be energized. As a result, if there is no change in the tilt angle of the vehicle body while the left crawler 10a and the right crawler 10b are stopped, it is not considered to have overturned, and the lithium-ion battery 20 can be used continuously.

[0034] If the result of step S206 is NO, it is determined whether the value of the boom rod pressure sensor 33 is less than or equal to a predetermined threshold (0 MPa in this embodiment) (step S205).

[0035] If the result of step S205 is YES, output terminal 30c is set to HIGH (step S202). As a result, if the tilt angle of the vehicle body changes even though the vehicle body is not jacked up, the shut-off relay 23 turns ON, and the lithium-ion battery 20 becomes unpowered.

[0036] Note that each of the judgments in steps S203 to S206 is performed before the tilt angle reaches threshold A (the result of the judgment in step S201 becomes YES). Therefore, there is a high probability that the shut-off relay 23 will be switched off before the vehicle body overturns and hits the ground. In that case, even if the controller 30 malfunctions due to the impact of the overturning, the shut-off relay 23 will be kept in the shut-off state by the action of the self-holding relay 36. After that, if the vehicle body is returned to a normal position with a crane or the like, or if the vehicle body is moved for a short time to recover, the lithium-ion battery 20 can be returned to a powered state by pressing the release switch 37.

[0037] (summary) In this embodiment, the vehicle comprises a traveling body 1, a rotating body 2 rotatably attached to the traveling body 1 and constituting the vehicle body together with the traveling body 1, a work device 3 rotatably attached to the rotating body 2, a plurality of actuators 7, 8, 9, 11a, 11b that drive the traveling body 1, the rotating body 2, and the work device 3, a main pump 14 (hydraulic pump) that supplies hydraulic fluid to the plurality of actuators 7, 8, 9, 11a, 11b, an electric motor 12 that drives the main pump 14, a lithium-ion battery 20, and a lithium-ion battery In a hydraulic excavator (electric construction machine) equipped with an inverter 22 connected to a lithium-ion battery 20 via a power supply circuit 21, which converts the DC power of the lithium-ion battery 20 into AC power and supplies it to an electric motor 12, the machine further includes a tilt sensor 31 for detecting the tilt angle of the traveling body 1 or the slewing body 2, a shut-off relay 23 for conducting or shutting off the power supply circuit 21, and a controller 30 that switches the shut-off relay 23 so that the power supply circuit 21 is shut off when the value of the tilt sensor 31 exceeds a predetermined threshold A (first threshold).

[0038] According to this embodiment configured as described above, when the vehicle body 1 or the turning body 2 is tilted significantly, the power supply circuit 21 connecting the lithium-ion battery 20 and the inverter 22 is shut off. This prevents electrical circuit failures of the lithium-ion battery 20 or peripheral equipment caused by the lithium-ion battery 20 remaining powered while the vehicle body is overturned.

[0039] Furthermore, in this embodiment, the vehicle 1 has a left crawler 10a and a right crawler 10b, and the plurality of actuators 7, 8, 9, 11a, 11b include a left drive motor 11a that drives the left crawler 10a and a right drive motor 11b that drives the right crawler 10b. The controller 30 stores the value of the tilt sensor 31 as a reference tilt angle B immediately after the controller 30 is started or immediately after the left drive motor 11a and the right drive motor 11b stop. When the vehicle 1 is not jacked up and the left drive motor 11a and the right drive motor 11b are stopped, the controller 30 switches the shut-off relay 23 so that the power supply circuit 21 is shut off if the difference between the value of the tilt sensor 31 and the reference tilt angle B exceeds, for example, the detection accuracy (second threshold) of the tilt sensor 31.

[0040] Furthermore, in this embodiment, the vehicle 1 has a left crawler 10a and a right crawler 10b, and the multiple actuators 7, 8, 9, 11a, 11b include a left drive motor 11a that drives the left crawler 10a and a right drive motor 11b that drives the right crawler 10b, and the controller 30 switches the shut-off relay 23 so that the power supply circuit 21 is shut off when the left drive motor 11a or the right drive motor 11b slips while the vehicle 1 is not jacked up. This makes it possible to stop the power supply to the lithium-ion battery 20 when traveling on a slope or when the vehicle body is tilted even when not jacked up.

[0041] Furthermore, in this embodiment, the work device 3 has a boom 4 rotatably attached to the slewing body 2, and a plurality of actuators 7, 8, 9, 11a, 11b include a boom cylinder 7 that drives the boom 4, and the hydraulic excavator is equipped with a boom rod pressure sensor 33 that detects the rod-side pressure of the boom cylinder 7, and the controller 30 determines whether or not the traveling body 1 is jacked up based on the value of the boom rod pressure sensor 33. This makes it possible to detect the state in which the traveling body 1 is jacked up based on the rod-side pressure of the boom cylinder 7.

[0042] Furthermore, the hydraulic excavator in this embodiment includes a left travel pilot pressure sensor 32a for detecting the pilot pressure of the left travel motor 11a, a right travel pilot pressure sensor 32b for detecting the pilot pressure of the right travel motor 11b, a left travel drive pressure sensor 34a for detecting the drive pressure of the left travel motor 11a, and a right travel drive pressure sensor 34b for detecting the drive pressure of the right travel motor 11b. The controller 30 determines that the left crawler 10a is slipping based on the values ​​of the left travel pilot pressure sensor 32a and the left travel drive pressure sensor 34a, and determines that the right crawler 10b is slipping based on the values ​​of the right travel pilot pressure sensor 32b and the right travel drive pressure sensor 34b. This makes it possible to detect whether the left crawler 10a or the right crawler 10b is slipping based on the pilot pressure of the left travel motor 11a, the pilot pressure of the right travel motor 11b, the drive pressure of the right travel motor 11b, and the drive pressure of the left travel motor 11a.

[0043] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above and includes various modifications. For example, the embodiments described above have been described in detail for the purpose of explaining the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to having all the configurations described above. [Explanation of Symbols]

[0044] 1...Travel body, 2...Slewing body, 3...Working device, 4...Boom, 5...Arm, 6...Bucket, 7...Boom cylinder (actuator), 8...Arm cylinder (actuator), 9...Bucket cylinder (actuator), 10a...Left crawler, 10b...Right crawler, 11a...Left travel motor (actuator), 11b...Right travel motor (actuator), 12...Electric motor, 13...Gear pump, 14...Main pump (hydraulic pump), 15...Pilot valve, 16...Control valve, 20...Lithium-ion battery, 21...Power supply circuit, 22...Inverter, 23...Shut-off relay 23a...Switch side circuit, 23b...Normally closed side contact, 23c...Coil side circuit, 23d...Normally open side contact, 24...Lead-acid battery, 25...Key switch, 29...Release switch, 30...Controller, 30a...Memory device, 30b...Input terminal, 30c...Output terminal, 31...Tilt sensor, 32a...Left travel pilot pressure sensor, 32b...Right travel pilot pressure sensor, 33...Boom rod pressure sensor, 34a...Left travel drive pressure sensor, 34b...Right travel drive pressure sensor, 35...Protection diode, 36...Self-holding relay, 36a...Coil side circuit, 36b...Switch side circuit, 37...Release switch.

Claims

1. The vehicle and A swivel body is rotatably attached to the aforementioned traveling body and, together with the traveling body, constitutes the vehicle body. A work device rotatably attached to the aforementioned rotating body, Multiple actuators that drive the traveling body, the rotating body, and the working device, A hydraulic pump that supplies hydraulic fluid to the plurality of actuators, An electric motor that drives the hydraulic pump, Lithium-ion battery, An electric construction machine comprising an inverter connected to the lithium-ion battery via a power supply circuit, which converts the DC power of the lithium-ion battery into AC power and supplies it to the electric motor, An inclination sensor for detecting the inclination angle of the traveling body or the turning body, A tripping relay for conducting or interrupting the power supply circuit, The system includes a controller that switches the shut-off relay so that the power supply circuit is shut off when the value of the tilt sensor exceeds a predetermined first threshold. An electric construction machine characterized by the following features.

2. In the electric construction machine according to claim 1, The aforementioned vehicle has a left crawler and a right crawler, The plurality of actuators include a left drive motor that drives the left crawler and a right drive motor that drives the right crawler. The aforementioned controller, The values ​​of the tilt sensors immediately after the controller is started, or immediately after the left and right motors stop, are stored as the reference tilt angle. When the vehicle is not jacked up and the left and right motors are stopped, and the difference between the tilt sensor value and the reference tilt angle exceeds a predetermined second threshold, the power supply circuit is shut off by switching the shut-off relay. An electric construction machine characterized by the following features.

3. In the electric construction machine according to claim 1, The aforementioned vehicle has a left crawler and a right crawler, The plurality of actuators include a left drive motor that drives the left crawler and a right drive motor that drives the right crawler. The controller switches the shut-off relay so that the power supply circuit is shut off when the left or right motor of the vehicle slips while the vehicle is not jacked up. An electric construction machine characterized by the following features.

4. In the electric construction machine according to claim 2 or 3, The aforementioned work device has a boom that is rotatably attached to the rotating body, The plurality of actuators include a boom cylinder that drives the boom, The electric construction machine is equipped with a boom rod pressure sensor that detects the rod-side pressure of the boom cylinder, The aforementioned controller, Based on the value of the boom rod pressure sensor, it is determined whether or not the vehicle is jacked up. An electric construction machine characterized by the following features.

5. In the electric construction machine according to claim 3, A left-side pilot pressure sensor for detecting the pilot pressure of the left-side motor, A right-hand drive pilot pressure sensor for detecting the pilot pressure of the right-hand drive motor, A drive pressure sensor for the left drive motor detects the drive pressure of the left drive motor, The system includes a drive pressure sensor for the right drive motor that detects the drive pressure of the right drive motor, The aforementioned controller, Based on the value of the left driving pilot pressure sensor and the value of the left driving drive pressure sensor, it is determined that the left crawler is slipping. Based on the value of the aforementioned right-hand pilot pressure sensor and the value of the aforementioned right-hand drive pressure sensor, it is determined that the right crawler is slipping. An electric construction machine characterized by the following features.

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