ELECTRIC TOOL

Abstract

There is provided a compact, lightweight, hydraulic electric tool which can perform a long-term operation by minimizing power consumption while preventing operation efficiency from being degraded due to a hot electric motor. An electric tool includes a main body having an oil tank, a hydraulic pump for feeding hydraulic oil to a cylinder part, and an electric motor for driving the hydraulic pump, and a tool head operated by a pressing force of a piston in the cylinder part in a state where the tool head is coupled to the main body. The oil tank is configured to cover a motor case.

Claims

1. An electric tool comprising: a main body having a cylinder part, an oil tank, a hydraulic pump for feeding hydraulic oil inside the oil tank to the cylinder part, and an electric motor for driving the hydraulic pump; and a tool head operated by a pressing force of a piston in the cylinder part in a state where the tool head is coupled to the main body, wherein a motor case in the electric motor is covered with the oil tank.

2. The electric tool according to claim 1, wherein one end part of the oil tank is locked to the motor case, and the other end part is locked to the hydraulic pump.

3. The electric tool according to claim 1, wherein the electric motor is a brushless motor, and is coupled to the hydraulic pump via a speed reducer.

4. The electric tool according to claim 2, wherein the electric motor is a brushless motor, and is coupled to the hydraulic pump via a speed reducer.

5. The electric tool according to claim 1, wherein the motor case in the electric motor is provided with a fin, and the fin is configured to come into contact with the hydraulic oil inside the oil tank.

6. The electric tool according to claim 2, wherein the motor case in the electric motor is provided with a fin, and the fin is configured to come into contact with the hydraulic oil inside the oil tank.

7. The electric tool according to claim 1, wherein the hydraulic pump includes a swash plate cam that rotates around an axis passing through a drive shaft of the electric motor, a plurality of plungers disposed around the axis passing through the drive shaft in the cylinder part, and reciprocating while coming into contact with the swash plate cam, and a check valve, and is configured to feed the hydraulic oil from the oil tank to the cylinder part via the check valve.

8. The electric tool according to claim 2, wherein the hydraulic pump includes a swash plate cam that rotates around an axis passing through a drive shaft of the electric motor, a plurality of plungers disposed around the axis passing through the drive shaft in the cylinder part, and reciprocating while coming into contact with the swash plate cam, and a check valve, and is configured to feed the hydraulic oil from the oil tank to the cylinder part via the check valve.

9. The electric tool according to claim 1, further comprising: a rechargeable battery that supplies power to the electric motor; and an adapter that connects the rechargeable battery to the main body.

10. The electric tool according to claim 2, further comprising: a rechargeable battery that supplies power to the electric motor; and an adapter that connects the rechargeable battery to the main body.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0017] FIG. 1 is a schematic side view illustrating an example of an electric tool according to an embodiment of the present invention.

[0018] FIG. 2 is a schematic internal structure diagram illustrating an internal structure in the electric tool in FIG. 1.

[0019] FIG. 3A is a schematic sectional view in which an internal structure of a drive system in the electric tool in FIG. 1 is illustrated in a side view, FIG. 3B is a schematic sectional view in which the internal structure of the drive system in the electric tool in FIG. 1 is illustrated in a plan view, FIG. 3C is a sectional view taken along line C-C in FIG. 3B, and FIG. 3D is a partial sectional view when a viewing angle in FIG. 3B is changed.

DESCRIPTION OF EMBODIMENTS

[0020] Hereinafter, an embodiment according to the present invention will be described in detail with reference to the drawings. The present embodiment provides an electric tool 1 such as an electric cutting machine, an electric pressing machine, and an electric crimping machine. In all drawings for describing the embodiment, the same reference numerals will be assigned to members having the same function, and repeated description thereof may be omitted in some cases.

[0021] FIGS. 1 and 2 are schematic views illustrating an example of the electric tool 1 according to the present embodiment. The electric tool 1 is a cordless type hydraulic electric tool including a main body 2, a tool head 9 operated by a pressing force of a piston 4a in a cylinder part 4 of the main body 2 in a state where the tool head 9 is coupled to the main body 2, and a rechargeable battery 5b for supplying power to an electric motor 8 of the main body 2. The electric tool 1 is gripped and used by a hand of an operator at a jobsite. The piston 4a reciprocates along an axis P1 of a drive shaft 8a of the electric motor 8. That is, the piston 4a moves forward to a side of an arrow in a Y-direction in the drawing, and moves rearward to a side opposite to the arrow in the Y-direction in the drawing. FIG. 1 illustrates an example of the electric tool 1 configured to include the tool head 9 for electric pressing machine. The electric tool 1 may be a dedicated tool to which the tool head 9 is directly coupled, or may be a multi-function tool in which the tool head 9 is exchangeable. Here, in order to facilitate description of a positional relationship of each part of the electric tool 1, directions are indicated by arrows X, Y, and Z in the drawing. The electric tool 1 is normally operated in any direction.

[0022] As illustrated in FIGS. 2 and 3A to 3C, the main body 2 includes the cylinder part 4, a hydraulic pump 7 coupled to the cylinder part 4 to have an integral structure, and an oil tank 3 attached to an outer side of the hydraulic pump 7 and attached to an outer side of the electric motor 8. In the cylinder part 4, the piston 4a is disposed in a piston chamber 4b, and a coil spring 4c is disposed along an outer periphery of the piston 4a in alignment with an axis of the piston 4a. The hydraulic pump 7 feeds hydraulic oil 3c stored in the oil tank 3 to the piston chamber 4b of the cylinder part 4.

[0023] The main body 2 includes the electric motor 8 coupled to the hydraulic pump 7 via a speed reducer 6 to drive the hydraulic pump 7, and a control circuit 27 that performs driving control on the electric motor 8. The rechargeable battery 5b for supplying power to the electric motor 8 and the control circuit 27 is connected to an adapter 5a of the main body 2 in a state of a battery pack. The adapter 5a is coupled to a rear end part of the main body 2. The tool head 9, the main body 2, the adapter 5a, and the rechargeable battery 5b are disposed in order in a direction of the axis P1. A handle 2d as a hand portion gripped by an operator is provided to form an integral structure with a housing 2a in the main body 2 in a central part of the main body 2 in the direction of the axis P1. The handle 2d has a start switch 2c for starting the electric motor 8 and feeding the hydraulic oil 3c stored in the oil tank 3 to the cylinder part 4, and a return switch 2e for returning the hydraulic oil 3c from the cylinder part 4 to the oil tank 3. Here, the battery pack configured to include the rechargeable battery 5b such as a lithium-ion battery and a nickel-metal hydride battery is connected to the adapter 5a of the main body 2, and the adapter 5a is coupled to the main body 2. According to this configuration, the electric tool 1 is excellent in portability.

[0024] As an example, the electric motor 8 is an inner rotor type brushless motor. As an example, a motor case 8c in the electric motor 8 is provided with a fin 8d for heat radiation, and a configuration is adopted in which the fin 8d can come into contact with the hydraulic oil 3c stored in the oil tank 3.

[0025] As illustrated in FIG. 3A, the hydraulic pump 7 includes a swash plate cam 7a coupled to the drive shaft 8a of the electric motor 8 to which the speed reducer 6 is directly coupled or the drive shaft 8a of the electric motor 8 having the speed reducer 6 and rotated by a driving force of the electric motor 8, and a plurality of plungers 12 disposed around the axis P1 passing through the drive shaft 8a in the cylinder part 4 and reciprocating while coming into contact with the swash plate cam 7a. A check valve 16 for preventing a backflow of the hydraulic oil 3c from the plunger 12 to the oil tank 3 is disposed at a position (position in a cross section taken along line C-C) close to the hydraulic pump 7 on a secondary side of the plunger 12.

[0026] The oil tank 3 is a bag-like body made of an oil-resistant, expandable, and contractible rubber material. A configuration is adopted in which the oil tank 3 is locked to both the hydraulic pump 7 and the electric motor 8, and the motor case 8c is covered with the oil tank 3. As illustrated in FIGS. 3A to 3D, a connection portion between the hydraulic pump 7 and the cylinder part 4 has a first pipe portion 21 for feeding the hydraulic oil 3c from the oil tank 3 to the cylinder part 4, and a check valve 15 is provided in an intermediate portion of the first pipe portion 21. In addition, a connection portion between the hydraulic pump 7 and the cylinder part 4 has a second pipe portion 22 for returning the hydraulic oil 3c from the cylinder part 4 to the hydraulic pump 7, and a return valve 26 is provided in an intermediate portion of the second pipe portion 22. A connection portion between the hydraulic pump 7 and the cylinder part 4 has a third pipe portion 23 for returning the hydraulic oil 3c from the cylinder part 4 to the hydraulic pump 7, and a relief valve 25 is provided in an intermediate portion of the third pipe portion 23.

[0027] One end part 3a of the oil tank 3 is locked to the motor case 8c, and the other end part 3b is locked to the hydraulic pump 7. As an example, the one end part 3a of the oil tank 3 is curled outward, and is locked and fixed to an outer peripheral groove of the motor case 8c by a first locking material 17a which is a rubber ring such as an O-ring or a binding band. Similarly, the other end part 3b of the oil tank 3 is curled outward, and is locked and fixed to an outer peripheral groove of the hydraulic pump 7 by a second locking material 17b which is a rubber ring such as an O-ring or a binding band.

[0028] According to the present embodiment, a configuration is adopted in which the hydraulic oil 3c inside the oil tank 3 absorbs the heat exhausted from the electric motor 8 or the speed reducer 6. In this manner, operation efficiency can be prevented from being degraded due to the hot electric motor 8 or the hot speed reducer 6. In addition, the existing hydraulic oil 3c is used for the main body 2. Therefore, the electric tool 1 can be compact and lightweight without increasing the number of components. The heat exhausted from the electric motor 8 or the speed reducer 6 can be used to raise a temperature of the hydraulic oil 3c. In this manner, viscosity of the hydraulic oil 3c can be lowered even under a low-temperature environment. Therefore, it is possible to adopt a configuration which enables a more efficient hydraulic operation.

[0029] As an example, the tool head 9 performs a gripping operation, a temporary gripping operation, or a gripping preparation operation in a low-pressure stage leading to a first pressure, and performs a pressing operation or a crimping operation in a high-pressure stage leading to a second pressure. When the tool head 9 completes predetermined work, the relief valve 25 is opened to reduce the pressure in the cylinder part 4. When a position of the piston 4a is returned, a return pin 28 is operated to open the return valve 26, and the hydraulic oil 3c is returned to the oil tank 3 by a restoring force of the coil spring 4c. The electric tool 1 may have an automatic return portion. In a configuration having the automatic return portion, the tool head 9 returns to a state before the work when the predetermined work is completed by the tool head 9.

[0030] The present invention is not limited to the embodiment described above, and various modifications can be made within the scope not departing from the present invention.