Electric construction machine

Abstract

A revolving frame 7 of an electric hydraulic excavator 1 includes: a bottom plate 7A extending in the front-back direction; and a left vertical plate 7B and a right vertical plate 7C fixed to an upper surface 7M of the bottom plate 7A and separated from each other in the left-right direction, the left vertical plate 7B and the right vertical plate 7C extending in the front-back direction. A battery support member 8 including rear end sides of the left vertical plate 7B and the right vertical plate 7C and supporting a battery 12 is provided on a rear part of the revolving frame 7. A reinforcement material 23 that extends in the left-right direction to span the left vertical plate 7B and the right vertical plate 7C and that reinforces the revolving frame 7 is provided on a lower surface 7L of the bottom plate 7A of the revolving frame 7, the lower surface 7L corresponding to the lower side of the battery support member 8.

Description

Electric Construction Machinery

[0001] The present disclosure relates to an electric construction machine such as a hydraulic excavator provided with an electric motor as a power source.

[0002] A hydraulic excavator, which is a representative example of construction machinery, includes a self-propelled lower traveling body, an upper revolving structure revolvably mounted on the lower traveling body, and a working device provided at a front portion of the upper revolving structure. In recent years, in order to suppress global warming and air pollution, electric hydraulic excavators equipped with an electric motor as a power source instead of an engine have been put into practical use. An electric hydraulic excavator is equipped with a battery that stores electric power for driving the electric motor.

[0003] In an electric hydraulic excavator, structures such as a vehicle body and a working device, and a hydraulic system are common to those of an engine-driven hydraulic excavator. A battery replacing the engine is mounted on a rear portion of a vehicle body frame of the electric hydraulic excavator. Here, in the case of hydraulic excavators with approximately the same bucket capacity, the weight of the battery mounted on the electric hydraulic excavator is larger than the weight of the engine mounted on the engine-driven hydraulic excavator. Therefore, when the electric hydraulic excavator is in operation, a large load acts on the vehicle body frame. In response to this, there has been disclosed a configuration that secures the strength of the vehicle body frame by providing a rib extending in the front-rear direction of the vehicle body on an upper surface of the vehicle body frame (Patent Document 1).

[0004] Japanese Patent Application Publication No. 2023-150760

[0005] However, according to the electric hydraulic excavator disclosed in Patent Document 1, the rib is disposed in a battery accommodation space formed at an upper portion of the vehicle body frame. Therefore, when the height of the rib is increased to enhance the strength of the vehicle body frame, the size (battery capacity) of the battery disposed in the battery accommodation space is limited. As a result, sufficient operating time of the electric hydraulic excavator cannot be ensured. On the other hand, when the height of the rib is reduced to increase the battery capacity, there is a problem that the strength of the vehicle body frame decreases because a large load acts on the vehicle body frame due to the weight of the battery.

[0006] The objective of the present invention is to provide an electric construction machine that can increase the strength of the vehicle frame while ensuring a large battery capacity.

[0007] The present invention relates to an electric construction machine having a self-propelled vehicle body and a work device provided on the vehicle body, wherein the vehicle body comprises a vehicle frame to which the work device is attached to the front, and a battery that supplies power to an electric motor which is a power source, and the vehicle frame has a bottom plate extending in the front-rear direction, and a left vertical plate and a right vertical plate fixed to the upper surface of the bottom plate spaced apart in the left-right direction and extending in the front-rear direction, and a battery support member is provided at the rear of the vehicle frame, which is composed of the rear ends of the left vertical plate and the right vertical plate and supports the battery, wherein a reinforcing member is provided on the lower surface of the bottom plate of the vehicle frame that corresponds to the lower side of the battery support member, extending in the left-right direction across the left vertical plate and the right vertical plate and reinforcing the vehicle frame.

[0008] According to the present invention, by providing a reinforcing material on the underside of the bottom plate of the vehicle body frame, the strength of the vehicle body frame can be increased while securing a large space for arranging the battery on the upper side of the vehicle body frame.

[0009] This is a left side view showing an electric hydraulic excavator according to an embodiment of the present invention. This is a top view of the electric hydraulic excavator. This is a perspective view from the left rear showing the slewing frame with the battery and other components arranged on it. This is a bottom view of the slewing frame with the reinforcing material attached according to the first embodiment, viewed from below. This is a left side view showing the blade raised at the rear end of the slewing frame. This is an enlarged view showing the positional relationship between the blade and the reinforcing material in Figure 5. This is a bottom view of the slewing frame with the reinforcing material and additional reinforcing material attached according to the second embodiment, viewed from below. This is a bottom view of the slewing frame with the reinforcing material attached according to the third embodiment, viewed from below.

[0010] Hereinafter, an electric construction machine according to an embodiment of the present invention will be described in detail with reference to Figures 1 to 8, using the application of an electric hydraulic excavator as an example. In this embodiment, the travel direction of the electric hydraulic excavator will be described as the front-rear direction, and the direction perpendicular to the travel direction will be described as the left-right direction.

[0011] Figures 1 to 5 show a first embodiment of the present invention. The electric hydraulic excavator 1 comprises a crawler-type lower traveling body 2 that is self-propelled in the front-rear direction, and an upper rotating body 4 that is rotatably mounted on the lower traveling body 2 via a slewing device 3. The body of the electric hydraulic excavator 1 is composed of the lower traveling body 2 and the upper rotating body 4. A blade (dozer blade) 5 that rotates vertically between the ground and a slewing frame 7, which will be described later, is provided at the front of the lower traveling body 2. The blade 5 is composed of an arm 5A, a blade body 5B, and a blade cylinder (not shown). The base end of the arm 5A is pin-connected to the lower traveling body 2 so as to be able to swing vertically, and a plate-shaped blade body 5B extending horizontally is fixed to the tip of the arm 5A. A blade cylinder is provided between the arm 5A and the lower traveling body 2, and the blade cylinder extends and retracts in response to the operation of an operating lever located near the driver's seat 11C. As a result, the blade 5 swings vertically, and soil removal work is performed by the blade body 5B. A swing-type work device 6 is provided at the front of the upper rotating body 4, and this work device 6 is used for excavation work of earth and sand, etc.

[0012] The swing-type work device 6 includes a swing post 6A that is pivotably mounted on the front of the slewing frame 7 (described later) so as to swing in the left-right direction, a boom 6B that is rotatably attached to the swing post 6A, an arm 6C that is rotatably attached to the tip of the boom 6B, and a bucket 6D that is rotatably attached to the tip of the arm 6C so as to swing in the up-down direction. The work device 6 also includes a swing cylinder (not shown) for swinging the swing post 6A, a boom cylinder 6E for rotating the boom 6B, an arm cylinder 6F for rotating the arm 6C, and a bucket cylinder 6G for rotating the bucket 6D.

[0013] The upper rotating body 4 is mounted on the lower traveling body 2 via a rotating device 3 so as to be rotatable, and performs a rotating operation on the lower traveling body 2. The upper rotating body 4 is composed of a rotating frame 7 (described later), a battery support member 8, a support member 9, an electric motor and a hydraulic pump (neither of which are shown), a cab 11, and a battery 12.

[0014] The slewing frame 7, which serves as the vehicle body frame, forms the base of the upper slewing body 4. The slewing frame 7 is mounted on the lower traveling body 2 via a slewing device 3, and a work device 6 is attached to the front of the slewing frame 7.

[0015] As shown in Figures 3 and 4, the swivel frame 7 is composed of a bottom plate 7A, a left vertical plate 7B and a right vertical plate 7C, a horizontal plate 7D, a rear end connecting plate 7E, a left side frame 7F, and a right side frame 7G. The swivel frame 7 is capable of swiveling around the swivel center P relative to the lower traveling body 2. The bottom plate 7A of the swivel frame 7 is made of a thick steel plate that extends in the front-rear direction and is positioned in the center in the left-right direction. The left vertical plate 7B and the right vertical plate 7C are erected on the upper surface 7M of the bottom plate 7A and extend in the front-rear direction while facing each other in the left-right direction. The middle portions of the left vertical plate 7B and the right vertical plate 7C in the front-rear direction are connected to the horizontal plate 7D which extends in the left-right direction. The rear end connecting plate 7E connects the rear end of the left vertical plate 7B and the rear end of the right vertical plate 7C and extends in the left-right direction. The left side frame 7F is fixed to the tip of the left overhang beam 7F1 that extends to the left from the bottom plate 7A and the left vertical plate 7B, and extends in the front-to-back direction. The right side frame 7G is fixed to the tip of the right overhang beam 7G1 that extends to the right from the bottom plate 7A and the right vertical plate 7C, and extends in the front-to-back direction.

[0016] The distance between the left vertical plate 7B and the right vertical plate 7C decreases from the rear to the front, and cylindrical support bodies 7H are provided at the front ends of the left vertical plate 7B and the right vertical plate 7C. The swing post 6A of the work device 6 is supported by the support bodies 7H so that it can swing from side to side. The rear end 7J of the slewing frame 7 in the front-rear direction is formed in an arc shape with respect to the pivot center P. A battery support member 8 for supporting the battery 12 is provided between the horizontal plate 7D and the rear end 7J of the slewing frame 7.

[0017] The battery support member 8 is positioned behind the horizontal plate 7D of the slewing frame 7. The battery support member 8 has a left plate 8A, a right plate 8B, and a rear end connecting plate 7E, and is formed in a U-shaped frame when viewed from above. The left plate 8A is made up of the portion of the left vertical plate 7B that extends rearward from the horizontal plate 7D, and the right plate 8B is made up of the portion of the right vertical plate 7C that extends rearward from the horizontal plate 7D. Thus, the battery support member 8 is made up of the rear ends of the left vertical plate 7B and the right vertical plate 7C of the slewing frame 7 and the rear end connecting plate 7E.

[0018] The polygonal area enclosed by the lateral plate 7D of the slewing frame 7 and the battery support member 8 is the battery housing section 7K. The battery 12 is attached to the battery support member 8 via a mounting member 16, etc., which will be described later, and the lower side of the battery 12 is housed in the battery housing section 7K in a state where it is spaced apart (floating) from the bottom plate 7A of the slewing frame 7.

[0019] Support brackets 8C are attached to the left plate 8A, the right plate 8B, and the rear end connecting plate 7E of the battery support member 8. These multiple support brackets 8C support the battery 12 via the battery-side bracket 12C and mounting member 16, which will be described later.

[0020] The support member 9 is positioned behind the horizontal plate 7D and is erected on the swivel frame 7 so as to surround the battery 12. The support member 9 consists of a left leg portion 9A, a right leg portion 9B, a horizontal beam portion 9C, etc., and supports the rear end of the cab 11 as well as the exterior cover 22, which will be described later.

[0021] The left leg portion 9A is positioned behind the horizontal plate 7D of the left side frame 7F and rises upward from the left side frame 7F to the left side of the battery 12. The left leg portion 9A is bent in an L-shape, and its lower end is fixed to the left overhang beam 7F1. The upper end of the left leg portion 9A is bent to the right (towards the battery 12) and is attached to the crossbeam portion 9C, which will be described later.

[0022] The right leg section 9B is positioned behind the horizontal plate 7D of the right side frame 7G and rises upward from the right side frame 7G to the right of the battery 12. The right leg section 9B consists of a front frame section 9B1 and a rear frame section 9B2, which are joined together in an L-shape when viewed from above by welding or the like. The front frame section 9B1 of the right leg section 9B extends in the left-right direction between the right vertical plate 7C and the right side frame 7G. The rear frame section 9B2 of the right leg section 9B extends rearward from the left end of the front frame section 9B1, and the upper end of the front frame section 9B1 is connected to the horizontal beam section 9C. A radiator 10 (see Figure 2) for cooling electrical equipment such as the charger 19 and inverter 20, which will be described later, is attached to the rear frame section 9B2.

[0023] The crossbeam section 9C connects the upper end of the left leg section 9A and the upper end of the right leg section 9B (front frame section 9B1), and extends horizontally above the battery 12. The left end of the crossbeam section 9C is fixed to the left leg section 9A using bolts, etc., and the right end of the crossbeam section 9C is fixed to the right leg section 9B using bolts, etc. Two mounting holes 9C1 are provided on the upper surface of the crossbeam section 9C, spaced apart horizontally, and mounting members (not shown) for supporting the rear end of the cab 11 are attached to the mounting holes 9C1.

[0024] A reinforcing plate 9D is provided between the crossbeam 9C and the left side plate 8A of the battery support member 8. The upper end of the reinforcing plate 9D is fixed to the left end of the crossbeam 9C using bolts, and the lower end of the reinforcing plate 9D is fixed to the left side plate 8A of the battery support member 8 using bolts, etc. The reinforcing plate 9D reinforces the support member 9 and also functions as a bracket for attaching the AC box 18, which will be described later.

[0025] The cab 11 is mounted on the front left side of the slewing frame 7. The cab 11 consists of a base floor member 11A and a cab box 11B positioned on the floor member 11A, forming the operator's cabin. The rear of the floor member 11A is inclined diagonally upward, and the rear end of the floor member 11A is supported by the crossbeam portion 9C of the support member 9. Specifically, the rear end of the floor member 11A is attached to the crossbeam portion 9C via a vibration-damping mount (not shown) located in the mounting hole 9C1 of the crossbeam portion 9C.

[0026] Inside the cab 11, there is a driver's seat 11C where the operator sits, and around the driver's seat 11C are travel levers and pedals and work operation levers (neither of which are shown) for operating the electric hydraulic excavator 1. By operating the travel levers and pedals and work operation levers, the operator can perform travel operations with the lower travel body 2, rotation operations with the upper slewing body 4, excavation work with the work device 6, etc.

[0027] The battery 12 is positioned at the rear end of the slewing frame 7, supported by a battery support member 8. The battery 12 is formed in the shape of a rectangular block by housing a plurality of battery modules (not shown), for example, lithium-ion batteries, within a housing. The plurality of battery modules constituting the battery 12 are densely housed within the housing, and the battery 12 has a large mass. The battery 12 supplies power to electric equipment such as the electric motor 13. The electric motor 13 drives the hydraulic pump 14 with power supplied from the battery 12. The hydraulic pump 14 pressurizes the hydraulic oil stored in the hydraulic oil tank 15 and discharges pressurized oil to be supplied to various hydraulic actuators mounted on the electric hydraulic excavator 1.

[0028] Battery-side brackets 12C are attached to the front (not shown), rear 12A, and left side 12B of the battery 12. These battery-side brackets 12C are attached to a plurality of support brackets 8C, which are attached to the battery support member 8, via mounting members 16 having an elastic material such as rubber.

[0029] Multiple battery-side brackets 12C attached to the battery 12 are each positioned in the middle of the battery 12 in the vertical direction. As a result, the battery 12 is supported by the battery support member 8 via multiple mounting members 16 at a position close to the center of gravity, and the lower end of the battery 12 is housed in the battery housing 7K while floating above the bottom plate 7A of the slewing frame 7. In this way, by supporting the battery 12 by the battery support member 8 via multiple mounting members 16 at a position close to the center of gravity, it is possible to suppress the upper part of the battery 12 from swaying in the front-rear and side-to-side directions when the electric hydraulic excavator 1 is in operation.

[0030] A rapid charging inlet 17 is attached to the left overhanging beam 7F1 of the slewing frame 7. The rapid charging inlet 17 connects an external power supply (not shown) for rapid charging to the battery 12. An AC box 18 is attached to the reinforcing plate 9D of the support member 9. The AC box 18 monitors whether AC current is being supplied to the charger 19 from the external power supply and cuts off the supply of AC current if there is an abnormality. Electrical equipment such as the charger 19 and inverter 20 are arranged on the top surface 12D of the battery 12. The charger 19 converts the AC current supplied from the external power supply into DC current and supplies it to the battery 12. The inverter 20 controls the operation of the electric motor 13 by controlling the drive voltage supplied from the battery 12 to the electric motor 13.

[0031] The connecting member 21 is provided between the support member 9 and the battery support member 8, connecting the two. As shown in Figure 3, the connecting member 21 is formed from an L-shaped bent flat steel material and has a vertical plate 21A extending in the vertical direction and an upper plate 21B that bends forward from the upper end of the vertical plate 21A and extends in the front-rear direction. The front end of the upper plate 21B is fixed to the upper surface of the horizontal beam portion 9C that constitutes the support member 9 using bolts, and the lower end of the vertical plate 21A is fixed to the rear end connecting plate 7E of the battery support member 8 using bolts. This suppresses the front-rear swaying of the support member 9 (horizontal beam portion 9C) and also suppresses the front-rear swaying of the rear end connecting plate 7E that constitutes the battery support member 8.

[0032] The exterior cover 22 is positioned on the slewing frame 7 while being supported by the support member 9. The exterior cover 22 covers the mounted equipment such as the battery 12, electric motor 13, and hydraulic pump 14 that are mounted on the slewing frame 7.

[0033] Next, the reinforcing material 23 used in this embodiment will be described.

[0034] The reinforcing member 23 is provided on the lower surface 7L of the bottom plate 7A that constitutes the slewing frame 7. As shown in Figures 1 and 4, the reinforcing member 23 is made of a thick rectangular steel plate that extends in the left-right direction as a whole, and is fixed by welding to the lower side of the battery support member 8 provided on the bottom plate 7A of the slewing frame 7. Specifically, the reinforcing member 23 has a front end 23A, a rear end 23B, a left end 23C, and a right end 23D, and the lower surface 23E of the reinforcing member 23 protrudes downward from the lower surface 7L of the slewing frame 7 (bottom plate 7A). Here, the lower surface 23E of the reinforcing member 23 is positioned above the arm 5A of the blade 5 when the blade 5 provided on the lower traveling body 2 is raised to the upper limit position that can be raised by the blade cylinder (see Figure 6). The rear end 23B of the reinforcing member 23 is positioned closer to the slewing center P of the upper slewing body 4 than the rear end 7J of the slewing frame 7, and is formed in an arc shape centered on the slewing center P.

[0035] The front end 23A of the reinforcing member 23 is joined to the rear end connecting plate 7E of the battery support member 8 via a plurality of front welds (weld beads) 24 at a position away from the front. The left end 23C of the reinforcing member 23 is joined to the lower side of the left plate 8A of the battery support member 8 via a left weld 25. The right end 23D of the reinforcing member 23 is joined to the lower side of the right plate 8B of the battery support member 8 via a right weld 26. Here, the left plate 8A of the battery support member 8 constitutes the rear part of the left vertical plate 7B of the slewing frame 7, and the right plate 8B of the battery support member 8 constitutes the rear part of the right vertical plate 7C of the slewing frame 7. Therefore, the reinforcing member 23 is fixed to the lower surface 7L of the bottom plate 7A in a state that extends in the left-right direction across the left vertical plate 7B and the right vertical plate 7C of the slewing frame 7, thereby reinforcing the slewing frame 7.

[0036] The rear end portion 23B of the reinforcing member 23 is joined to the battery support member 8 via a plurality of rear welds 27 at a position below the rear end connecting plate 7E. Since the rear end portion 23B is formed in an arc shape, both ends of the rear end portion 23B in the left-right direction are positioned in front of the rear end connecting plate 7E, and the central part of the rear end portion 23B in the left-right direction is positioned behind the rear end connecting plate 7E (see Figure 4). In this way, the reinforcing member 23 is fixed to the lower surface 7L of the bottom plate 7A, straddling the left vertical plate 7B and the right vertical plate 7C of the slewing frame 7, as well as the rear end connecting plate 7E which together with the left vertical plate 7B and the right vertical plate 7C constitute the battery support member 8. As a result, even if a large stress is generated on the rear side of the slewing frame 7 when the heavy battery 12 is attached, the slewing frame 7 can be effectively reinforced by the reinforcing member 23.

[0037] Here, we focus on the lengths of the multiple rear welds 27 formed between the reinforcing member 23 and the bottom plate 7A on the underside of the rear end connecting plate 7E of the battery support member 8. Of the multiple rear welds 27, the length L1 of the rear weld 27A formed at a position close to the support bracket 8C attached to the rear end connecting plate 7E is set to be greater than the length L2 of the rear welds 27 formed at a position further away from the support bracket 8C (L1 > L2). This makes it possible to concentrate the strength of the slewing frame 7 to which the rear end connecting plate 7E of the battery support member 8 is joined near the support bracket 8C that receives the load from the battery 12.

[0038] Furthermore, the rear end portion 23B of the reinforcing member 23 is formed in an arc shape centered on the pivot point P of the upper rotating body 4. As a result, as shown in Figures 5 and 6, even when the upper rotating body 4 is rotated with the blade 5 provided on the lower traveling body 2 raised to its upper limit position, contact between the blade 5 and the reinforcing member 23 can be avoided.

[0039] The electric hydraulic excavator 1 according to this embodiment has the configuration described above. When performing excavation work using the electric hydraulic excavator 1, the operator boards the cab 11 and operates the electric motor 13 to drive the hydraulic pump 14. In this state, the operator drives the electric hydraulic excavator 1 to the work site by operating the travel levers and pedals (not shown) inside the cab 11. Furthermore, by operating the work operation levers (not shown), the operator can rotate the upper slewing body 4 and perform excavation work on soil and sand using the work device 6.

[0040] When the electric hydraulic excavator 1 is in operation, excavation work is performed using the work device 6 located on the front end of the slewing frame 7, causing the entire vehicle to shake significantly in the front-to-back direction. As a result, the heavy battery 12 generates large vibrations such as pitching. The vibrations of the battery 12 are transmitted to the battery support member 8 via multiple battery-side brackets 12C, mounting members 16, and support brackets 8C. Therefore, when the electric hydraulic excavator 1 is in operation, a large load acts on the battery support member 8, pressing it in the front-to-back direction, and large stresses are generated at the joint between the slewing frame 7 and the battery support member 8.

[0041] In contrast, in this embodiment, a reinforcing member 23 is fixed to the lower surface 7L of the bottom plate 7A, which is the base of the slewing frame 7, and corresponds to the lower side of the battery support member 8. The reinforcing member 23 extends in the left-right direction, straddling the left plate 8A and the right plate 8B of the battery support member 8, which constitute the rear part of the left vertical plate 7B and the right vertical plate 7C of the slewing frame 7. As a result, even if a large stress is generated at the joint between the slewing frame 7 and the battery support member 8 due to vibration of the battery 12, the slewing frame 7 can be effectively reinforced by the reinforcing member 23.

[0042] Furthermore, since the reinforcing member 23 is fixed to the lower surface 7L of the bottom plate 7A constituting the swing frame 7, there is no need to increase the height of, for example, the left vertical plate 7B and the right vertical plate 7C arranged on the bottom plate 7A of the swing frame 7. Therefore, the strength of the swing frame 7 can be increased while securing a large space for arranging the battery 12 on the upper surface 7M side of the swing frame 7. As a result, the capacity of the battery accommodating portion 7K formed on the swing frame 7 is increased, so that the battery 12 having a large battery capacity can be mounted, and the operating time of the electric hydraulic excavator 1 can be sufficiently ensured.

[0043] Further, since the reinforcing member 23 is fixed to the lower surface 7L of the swing frame 7, an increase in the swing radius of the upper swing body 4 can be prevented compared to, for example, a case where the reinforcing member is fixed to the rear end of the swing frame. Furthermore, by fixing the reinforcing member 23 to the lower surface 7L of the swing frame 7, design, painting and the like for maintaining the aesthetic appearance of the electric hydraulic excavator 1 can be eliminated, and costs can be reduced.

[0044] Thus, the electric hydraulic excavator 1 according to the embodiment includes a self-propelled vehicle body (the lower traveling body 2 and the upper swing body 4) and the working device 6 provided on the upper swing body 4. The upper swing body 4 includes the swing frame 7 to which the working device 6 is attached at a front portion, and the battery 12 that supplies electric power to the electric motor 13 serving as a power source. The swing frame 7 includes the bottom plate 7A extending in the front-rear direction, and the left vertical plate 7B and the right vertical plate 7C which are fixed to the upper surface 7M of the bottom plate 7A spaced apart in the left-right direction and extend in the front-rear direction. A battery support member 8 configured to include the rear end sides of the left vertical plate 7B and the right vertical plate 7C and support the battery 12 is provided at a rear portion of the swing frame 7. A reinforcing member 23 that extends in the left-right direction across the left vertical plate 7B and the right vertical plate 7C and reinforces the swing frame 7 is provided on the lower surface 7L of the bottom plate 7A of the swing frame 7 corresponding to the lower side of the battery support member 8.

[0045] With this configuration, even if vibrations from the battery 12 are transmitted to the battery support member 8 when the electric hydraulic excavator 1 is in operation, the stress generated at the joint between the slewing frame 7 and the battery support member 8 can be reduced by the reinforcing member 23. As a result, the strength of the slewing frame 7 can be increased without increasing the height of the left vertical plate 7B and the right vertical plate 7C, which are placed on the bottom plate 7A of the slewing frame 7, and a battery 12 with a large battery capacity can be mounted on the upper slewing body 4.

[0046] In this embodiment, the slewing frame 7 includes a rear end connecting plate 7E that extends in the left-right direction between the rear end of the left vertical plate 7B and the rear end of the right vertical plate 7C, connecting the two and forming a battery support member 8 together with the left vertical plate 7B and the right vertical plate 7C. The reinforcing member 23 is fixed to the lower surface 7L of the bottom plate 7A, straddling the left vertical plate 7B, the right vertical plate 7C, and the rear end connecting plate 7E. With this configuration, the left vertical plate 7B, the right vertical plate 7C, and the rear end connecting plate 7E, which are located on the rear end of the slewing frame 7, can be intensively reinforced by the reinforcing member 23 fixed to the bottom plate 7A, straddling them. As a result, the rear end of the slewing frame 7, which is subjected to a large load due to the vibration of the battery 12, can be efficiently reinforced, and the strength of the slewing frame 7 can be increased.

[0047] In this embodiment, the battery support member 8 is provided with a support bracket 8C for attaching the battery 12, and the reinforcing member 23 is fixed to the lower surface 7L of the bottom plate 7A by welding. The length of the rear weld portion 27 formed between the reinforcing member 23 and the bottom plate 7A of the slewing frame 7 is set to be greater at positions closer to the support bracket 8C than at positions further away from the support bracket 8C. With this configuration, the strength of the slewing frame 7 to which the rear end connecting plate 7E of the battery support member 8 is joined can be concentrated and increased near the support bracket 8C that receives the load from the battery 12.

[0048] In the embodiment, the vehicle body of the electric hydraulic excavator 1 comprises a self-propelled lower traveling body 2 and a swing frame 7 pivotably mounted on the lower traveling body 2. The lower traveling body 2 is provided with a blade 5 that rotates vertically between the ground and the swing frame 7. A rear end portion 23B of the reinforcing member in the front-rear direction is disposed at a position closer to a swing center P side of the lower traveling body 2 than a rear end portion 7J of the swing frame 7 in the front-rear direction, and is formed in an arc shape centered on the swing center P. A lower surface 23E of the reinforcing member 23 is disposed above the blade 5 in a state where the blade 5 is lifted to an upper limit position. According to this configuration, even when the upper swing structure 4 is swung in a state where the blade 5 is lifted to the upper limit position, contact between the blade 5 and the reinforcing member 23 can be avoided.

[0049] Next, Fig. 7 shows a second embodiment of the present invention. The embodiment is characterized in that an additional reinforcing member is attached to the lower surface of the reinforcing member. In the embodiment, the same reference numerals are given to the same constituent components as those in the first embodiment, and the description thereof will be omitted.

[0050] In Fig. 7, the additional reinforcing member 28 is detachably attached to the reinforcing member 23 fixed to a lower surface 7L of the swing frame 7 (a bottom plate 7A). The additional reinforcing member 28 is formed of a thick rectangular steel plate or the like extending in the left-right direction as a whole, and has a front end portion 28A, a rear end portion 28B, a left end portion 28C, and a right end portion 28D. A length dimension of the additional reinforcing member 28 in the left-right direction (a distance between the left end portion 28C and the right end portion 28D) is set to be equal to that of the reinforcing member 23, and a length dimension of the additional reinforcing member 28 in the front-rear direction (a distance between the front end portion 28A and the rear end portion 28B) is set to be smaller than that of the reinforcing member 23. A lower surface 28E of the additional reinforcing member 28 protrudes downward from a lower surface 23E of the reinforcing member 23. Here, the lower surface 28E of the additional reinforcing member 28 is disposed above an arm 5A of the blade 5 in a state where the blade 5 provided on the lower traveling body 2 is lifted to an upper limit position that can be lifted by a blade cylinder. A rear end portion 28B of the additional reinforcing member 28 is formed in an arc shape centered on the swing center P of the upper swing structure 4.

[0051] The additional reinforcing member 28 has a plurality (for example, four) of bolt insertion holes that penetrate in the vertical direction (plate thickness direction), and bolts 29 are inserted through each of these bolt insertion holes. The additional reinforcing member 28 is attached to the lower surface 23E of the reinforcing member 23 by screwing these bolts 29 into a plurality of bolt holes (not shown) formed in the lower surface 23E of the reinforcing member 23. The rear end portion 28B of the additional reinforcing member 28 is positioned closer to the pivot center P than the rear end portion 23B of the reinforcing member 23, preventing contact with the blade 5.

[0052] The electric hydraulic excavator 1 according to the second embodiment has an additional reinforcing member 28 attached to the reinforcing member 23, and its basic operation and effect are not particularly different from that of the first embodiment. However, according to this embodiment, the stability of the upper slewing body 4 in the front-rear direction can be adjusted by appropriately attaching the additional reinforcing member 28 to the reinforcing member 23 according to the weight of the battery 12 mounted on the slewing frame 7.

[0053] Next, Figure 8 shows a third embodiment of the present invention. The characteristic of this embodiment is that the reinforcing material is provided with a weight portion that corrects the position of the center of gravity of the vehicle body in the lateral direction. In this embodiment, the same reference numerals are used for the same components as in the first embodiment, and their descriptions are omitted.

[0054] In Figure 8, the reinforcing member 30 is fixed to the lower surface 7L of the swivel frame 7 (bottom plate 7A) in place of the reinforcing member 23 according to the first embodiment. The reinforcing member 30 has an asymmetrical shape in the left-right direction, and a weight portion 32, described later, is integrally formed on the left side of the reinforcing member 30. Specifically, the reinforcing member 30 is composed of a rectangular main body portion 31 extending in the left-right direction and a weight portion 32 protruding forward from the left end of the main body portion 31.

[0055] The main body portion 31 has a front end portion 31A, a rear end portion 31B, a left end portion 31C, and a right end portion 31D, and the rear end portion 31B is formed in an arc shape centered on the pivot center P of the upper rotating body 4. Similar to the reinforcing member 23 in the first embodiment, the main body portion 31 is fixed to the lower surface 7L of the bottom plate 7A via a front weld portion 24, a left weld portion 25, and rear weld portions 27, 27A, while straddling the left vertical plate 7B, the right vertical plate 7C, and the rear end connecting plate 7E of the rotating frame 7.

[0056] The weight portion 32 is located on the left end of the main body portion 31 (the corner where the front end portion 31A and the left end portion 31C intersect) and protrudes forward in a rectangular shape from the front end portion 31A of the main body portion 31. The weight portion 32 is joined to the bottom plate 7A by the front weld portion 32A, the left weld portion 32B, and the right weld portion 32C. In this case, the electric hydraulic excavator 1 has the battery 12 located in the center of the upper rotating body 4 in the left-right direction, and the radiator 10, electric motor 13, hydraulic pump 14, and hydraulic oil tank 15 are located on the right side of the upper rotating body 4. Therefore, when the reinforcing member 30 is not fixed to the rotating frame 7, the center of gravity G of the upper rotating body 4 is located to the right of the rotation center P of the upper rotating body 4 (see Figure 2). Therefore, by fixing the reinforcing member 30, which is provided with the weight portion 32, to the lower surface 7L of the slewing frame 7, the center of gravity of the upper slewing body 4 can be corrected by the weight portion 32.

[0057] The electric hydraulic excavator 1 according to the third embodiment has a reinforcing member 30 with a weight 32 integrally attached to the main body 31, and its basic operation and effect are not particularly different from that of the first embodiment. However, according to this embodiment, even if the center of gravity G of the upper slewing body 4 is biased to the right with respect to the pivot center P, the position of the center of gravity of the upper slewing body 4 can be corrected in the left-right direction by fixing the reinforcing member 30 to the slewing frame 7. As a result, the left-right stability of the upper slewing body 4 can be adjusted.

[0058] In this embodiment, the reinforcing member 23 is fixed to the lower surface 7L of the slewing frame 7 (bottom plate 7A) by welding. However, the present invention is not limited to this, and the reinforcing member may be fixed to the lower surface of the slewing frame using fasteners such as bolts.

[0059] 2 Lower running body (vehicle body) 4 Upper rotating body (vehicle body) 5 Blade 6 Working device 7 Rotating frame (vehicle frame) 7A Bottom plate 7B Left vertical plate 7C Right vertical plate 7E Rear end connecting plate (connecting plate) 7J Rear end 7L Bottom surface 7M Top surface 8 Battery support member 8C Support bracket 12 Battery 13 Electric motor 23, 30 Reinforcement members 23B, 28B Rear end 23E, 28E Bottom surface 24 Front weld 25 Left side weld 26 Right side weld 27 Rear weld 28 Additional reinforcement member 32 Weight section

Claims

1. An electric construction machine having a self-propelled vehicle body and a work device provided on the vehicle body, wherein the vehicle body comprises a vehicle frame to which the work device is attached to the front, and a battery that supplies power to an electric motor which is a power source, the vehicle frame having a bottom plate extending in the front-rear direction, and a left vertical plate and a right vertical plate fixed to the upper surface of the bottom plate spaced apart in the left-right direction and extending in the front-rear direction, and a battery support member is provided at the rear of the vehicle frame, comprising the rear ends of the left vertical plate and the right vertical plate and supporting the battery, wherein a reinforcing member is provided on the lower surface of the bottom plate of the vehicle frame corresponding to the lower side of the battery support member, extending in the left-right direction across the left vertical plate and the right vertical plate and reinforcing the vehicle frame.

2. The electric construction machine according to claim 1, wherein the vehicle frame is provided with a connecting plate that extends in the left-right direction between the rear end of the left vertical plate and the rear end of the right vertical plate, connecting the two, and together with the left vertical plate and the right vertical plate, constitutes the battery support member, and the reinforcing member is fixed to the lower surface of the bottom plate while straddling the left vertical plate, the right vertical plate and the connecting plate.

3. The electric construction machine according to claim 1, characterized in that the battery support member is provided with a support bracket for attaching the battery, the reinforcing member is fixed to the lower surface of the bottom plate by welding, and the length of the weld formed between the reinforcing member and the bottom plate of the vehicle frame is set to be greater at positions closer to the support bracket than at positions further away from the support bracket.

4. The electric construction machine according to claim 1, wherein the vehicle body comprises a self-propelled lower vehicle and a vehicle frame rotatably mounted on the lower vehicle, the lower vehicle is provided with a blade that rotates vertically between the ground and the vehicle frame, the rear end of the reinforcing member in the front-rear direction is positioned closer to the pivot center of the vehicle frame than the rear end of the vehicle frame in the front-rear direction and is formed in an arc shape centered on the pivot center, and the lower surface of the reinforcing member is positioned above the blade when it is raised to its upper limit position.

5. The electric construction machine according to claim 4, wherein an additional reinforcing member is detachably attached to the lower surface of the reinforcing member, and the rear end of the additional reinforcing member in the front-rear direction is positioned closer to the pivot center than the rear end of the reinforcing member in the front-rear direction.

6. The electric construction machine according to claim 1, characterized in that the reinforcing member is integrally provided with a weight portion for correcting the position of the center of gravity of the vehicle body in the left-right direction.

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