JP7847066B2 - electric construction machinery - Google Patents

Description

This invention relates to an electric construction machine.

Engine-driven construction machinery comprises an engine, a hydraulic pump driven by the engine, a hydraulic actuator driven by the hydraulic fluid pressurized by the hydraulic pump, a fan connected to the engine's output shaft, and a heat exchanger that cools the hydraulic fluid or cooling water with the cooling air generated by the fan. On the other hand, electric construction machinery replaces the engine with an electric motor and the fan connected to the engine's output shaft with an electric fan. Electric fans offer greater layout flexibility and easier speed control compared to fans connected to the engine's output shaft.

Patent Document 1 discloses an electric excavator, which is a type of electric construction machine. This electric excavator comprises a traveling body, a slewing body rotatably mounted above the traveling body, and a working device connected to the front of the slewing body. The slewing body includes a slewing frame, a cab-type driver's cabin located at the front of the slewing frame, a battery located at the rear of the slewing frame, a main storage compartment formed between the driver's cabin and the battery in the slewing frame, an electric motor, a hydraulic pump, a hydraulic oil tank, and a heat exchanger located in the main storage compartment, an opening/closing cover for opening and closing the opening of the main storage compartment, and an electric fan attached to the opening/closing cover.

Japanese Patent Publication No. 2021-063339

In electric construction machinery, since there is no engine, the noise from the electric fan is particularly noticeable. If the noise from the electric fan propagates through the structure of the electric construction machinery and reaches the operator's cab, it can disturb the operator inside. The structure interposed between the electric fan and the operator's cab should preferably be heavy, in order to increase sound attenuation and minimize vibration. In the electric excavator described in Patent Document 1, a hydraulic oil tank is interposed between the electric fan and the operator's cab. However, the hydraulic oil tank cannot be definitively said to be a structure that minimizes vibration or to be heavy. Therefore, there is room for improvement in reducing the transmission of electric fan noise to the operator's cab.

Furthermore, in the electric excavator described in Patent Document 1, the electric fan is covered by an opening/closing cover. Therefore, considering the possibility of collisions with flying objects or collisions with surrounding objects due to the rotation of the rotating body, there is room for improvement in protecting the electric fan.

This invention has been made in view of the above matters, and its objective is to provide an electric construction machine that can reduce the transmission of electric fan noise to the operator's cab and protect the electric fan.

To achieve the above objective, the present invention provides an electric construction machine comprising a traveling body, a slewing body rotatably mounted above the traveling body, and a working device connected to the front of the slewing body, wherein the slewing body comprises a slewing frame, a cab located at the front of the slewing frame, a counterweight located at the rear of the slewing frame, a battery located between the cab and the counterweight on the slewing frame, an electric motor driven by the battery, a hydraulic pump driven by the electric motor to pressurize the hydraulic fluid, an electric fan driven by the battery, and a heat exchanger that cools the hydraulic fluid or cooling water with the cooling air generated by the electric fan, wherein the electric fan is positioned such that the battery is interposed between it and the cab, and at least one of its upper, lower, left, and right sides is covered by the counterweight.

According to this invention, the transmission of electric fan noise into the driver's cab can be reduced, and the electric fan can be protected.

This is a perspective view showing the overall structure of an electric excavator in one embodiment of the present invention. This is a top view showing the equipment arrangement of the rotating body of an electric excavator in one embodiment of the present invention. This is a side view showing the equipment arrangement of the rotating body of an electric excavator in one embodiment of the present invention. This is a rear view showing the equipment arrangement of the rotating body of an electric excavator in one embodiment of the present invention. This diagram shows the configuration of the drive system for an electric excavator in one embodiment of the present invention.

One embodiment of the present invention will be described with reference to the drawings.

Figure 1 is a perspective view showing the overall structure of the electric excavator in this embodiment. Figures 2 to 4 are top, side, and rear views showing the equipment arrangement of the rotating body of the electric excavator in this embodiment. Note that, for convenience, some equipment is omitted from Figure 2.

The electric excavator of this embodiment comprises a traveling body 1, a slewing body 2 rotatably mounted above the traveling body 1, and a working device 3 connected to the front of the slewing body 2. The traveling body 1 moves by the rotation of a traveling motor (not shown), and the slewing body 2 rotates by the rotation of a slewing motor (not shown).

The work device 3 comprises a boom 4 rotatably connected vertically to the front of the slewing body 2, an arm 5 rotatably connected vertically to the tip of the boom 4, and a bucket 6 (working tool) rotatably connected vertically to the tip of the arm 5. The boom 4 rotates by the extension and retraction of the boom cylinder 7, the arm rotates by the extension and retraction of the arm cylinder 8, and the bucket 6 rotates by the extension and retraction of the bucket cylinder 9 (working tool cylinder). The bucket 6 is interchangeable with other working tools.

The slewing body 2 comprises a slewing frame 10 forming the lower base structure, a cab-type driver's cabin 11 located at the front of the slewing frame 10, a counterweight 12 located at the rear of the slewing frame 10, and a battery (e.g., a lithium-ion battery) 13 located between the driver's cabin 11 and the counterweight 12 on the slewing frame 10. The driver's cabin 11 is equipped with multiple operating devices (not shown) that can be operated by the driver.

The electric excavator is equipped with a drive system that drives multiple hydraulic actuators (specifically, the travel motor, slewing motor, boom cylinder 7, arm cylinder 8, and bucket cylinder 9 mentioned above) in response to the operation of multiple operating devices. Figure 5 shows the configuration related to the boom cylinder 7 in the drive system of the electric excavator in this embodiment.

The drive system of this embodiment comprises an inverter 14 that converts DC power from the battery 13 to AC power, an electric motor 15 driven by the power converted by the inverter 14, a hydraulic pump 16 and a pilot pump 17 driven by the electric motor 15, a control valve 18 that controls the flow of pressurized oil (specifically, direction and flow rate) from the hydraulic pump 16 to the boom cylinder 7, and an operating device 19 that switches the control valve 18. As described above, the operating device 19 is mounted in the operator's cab 11 of the slewing body 2, while the inverter 14, electric motor 15, hydraulic pump 16, pilot pump 17, and control valve 18 are mounted in other parts of the slewing body 2.

The operating device 19 includes an operating lever 20 that can be operated by the operator, a pilot valve 21a that reduces the discharge pressure of the pilot pump 17 to generate pilot pressure according to the amount of operation on one side of the operating lever 20, and a pilot valve 21b that reduces the discharge pressure of the pilot pump 17 to generate pilot pressure according to the amount of operation on the opposite side of the operating lever 20.

When the operator moves the control lever 20 to one side, the pilot pressure generated by the pilot valve 21a, corresponding to the amount of movement, is output to the pressure receiving section 22a of the control valve 18. This switches the control valve 18 to the switching position shown on the right in the diagram, and pressurized oil from the hydraulic pump 16 is supplied to the rod side of the boom cylinder 7 via the control valve 18, causing the boom cylinder 7 to retract. As a result, the boom 4 lowers.

When the operator moves the control lever 20 to the opposite side, the pilot pressure generated by the pilot valve 21b according to the amount of movement is output to the pressure receiving section 22b of the control valve 18. This switches the control valve 18 to the left-hand switching position shown in the figure, and pressurized oil from the hydraulic pump 16 is supplied to the bottom side of the boom cylinder 7 via the control valve 18, causing the boom cylinder 7 to extend. As a result, the boom 4 rises.

Returning to Figures 2 to 4 above, the counterweight 12 is composed of counterweight divisions 23a and 23b, which are divided in the left-right direction. Viewed from above, the overall shape is arc-shaped (in other words, a shape consisting of a circular arc and line segments connecting its ends). The counterweight divisions 23a and 23b are constructed, for example, by filling a steel container with heavy concrete. A storage chamber 24 is formed between the counterweight divisions 23a and 23b, and a cover (not shown) is attached to cover the upper and rear sides of the storage chamber 24.

A key feature of this embodiment is that the storage chamber 24 for the counterweight 12 houses the heat exchanger units 25a and 25b. Heat exchanger unit 25a consists of an electric fan 26a powered by the battery 13 and a heat exchanger (oil cooler) 27a that cools the hydraulic fluid with the cooling air generated by the electric fan 26a. Heat exchanger unit 25b consists of an electric fan 26b powered by the battery 13 and a heat exchanger (radiator) 27b that cools the cooling water with the cooling air generated by the electric fan 26b.

In this embodiment, configured as described above, the electric fans 26a and 26b are positioned such that a battery 13 is interposed between them and the driver's cab 11. The left and right sides (in other words, both sides in the width direction of the slewing body 2) are covered by counterweight divisions 23a and 23b (see Figures 2 to 4). The battery 13 is a heavy object with a structure that generates less vibration compared to, for example, a hydraulic oil tank. Therefore, the transmission of noise from the electric fans 26a and 26b to the driver's cab 11 can be reduced. Furthermore, the left and right sides of the electric fans 26a and 26b are covered by counterweight divisions 23a and 23b. Therefore, the electric fans 26a and 26b can be protected even if an object flies in and collides with them, or if the slewing body 2 collides with surrounding objects due to its rotation.

In the above embodiment, the counterweight 12 is divided into counterweight segments 23a and 23b, and the electric fans 26a and 26b are covered on the left and right sides by the counterweight segments 23a and 23b. However, the explanation is not limited to this configuration. The counterweight 12 does not need to be divided, and the electric fans 26a and 26b only need to be covered by the counterweight 12 on at least one of the top, bottom, left, and right sides. This allows for protection of the electric fans 26a and 26b, although the degree of protection may vary.

In the above description, the present invention has been explained using an electric excavator as an example of its application. However, it is not limited to this. That is, the present invention may be applied to other electric construction machinery besides electric excavators.

1. Traveling body 2. Rotating body 3. Working device 10. Rotating frame 11. Cab 12. Counterweight 13. Battery 15. Electric motor 16. Hydraulic pump 26a, 26b. Electric fan 27a, 27b. Heat exchanger

Claims (3)

The system comprises a traveling body, a rotating body rotatably mounted above the traveling body, and a working device connected to the front of the rotating body.
The electric construction machine comprises a slewing frame, a cab located at the front of the slewing frame, a counterweight located at the rear of the slewing frame, a battery located between the cab and the counterweight on the slewing frame, an electric motor driven by the battery, a hydraulic pump driven by the electric motor to pressurize the hydraulic fluid, an electric fan driven by the battery, and a heat exchanger that cools the hydraulic fluid or cooling water with the cooling air generated by the electric fan.
The electric construction machine is characterized in that the electric fan is positioned such that the battery is interposed between it and the driver's cab, and at least one of the upper, lower, left, and right sides is covered by the counterweight. In the electric construction machine according to claim 1,
The electric construction machine is characterized in that the electric fan is covered on the left and right sides by the counterweight. In the electric construction machine according to claim 2,
The aforementioned counterweight is characterized by having an overall shape that is curved when viewed from above, in an electric construction machine.