power tools

Abstract

To provide a hydraulic electric tool which is small and lightweight and enables reduction of electric power consumption to perform extended activity while preventing a motor from being heated to high temperature and deteriorating working efficiency.SOLUTION: An electric tool 1 includes: a body 2 having an oil tank 3, a hydraulic pump 7 which sends a hydraulic oil 3c to a cylinder part 4, and a motor 8 which drives the hydraulic pump 7; and a tool head 9 which is operated by pressing force of a piston in a cylinder part 4 while connected to the body 2. The oil tank 3 covers a motor case 8c.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a hydraulic power tool. [Background technology]

[0002] BACKGROUND ART Hydraulic power tools are known in the art (Patent Document 1: JP 2018-086696 A). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-086696 Summary of the Invention [Problem to be solved by the invention]

[0004] When a power tool repeatedly performs tool head operations such as cutting, fastening, compressing, or crimping in a short period of time, the motor heats up and reduces its operating efficiency. Continued use of the power tool with a hot motor can lead to motor burnout. Conventionally, air-cooled or water-cooled structures using refrigerants have been proposed to prevent motor burnout by forcibly cooling the motor. However, air-cooled structures require the provision of a ventilation window in the housing, which makes them prone to malfunction due to the intrusion of foreign matter such as dust and water droplets, significantly limiting the operating environment. Without a ventilation window, the cooling effect is significantly reduced, making continuous use difficult. Water-cooled structures are large and heavy, making them unsuitable for small power tools. Therefore, there is a market demand for compact, lightweight hydraulic power tools that can reduce power consumption and perform long-term work while preventing motor efficiency from decreasing due to high temperatures even when the tool head is repeatedly operated in a short period of time. [Means for solving the problem]

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a small, lightweight hydraulic power tool that can reduce power consumption and perform work for long periods of time, while preventing the motor from becoming too hot and reducing operating efficiency.

[0006] In one embodiment, the above problem is solved by the solution disclosed below.

[0007] The power tool according to the present invention includes a cylinder portion, an oil tank, and a hydraulic pump that sends hydraulic oil from the oil tank to the cylinder portion. a reducer connected to the hydraulic pump, and a An electric power tool including a main body having a motor that drives the hydraulic pump, and a tool head that is connected to the main body and operates by the pressing force of a piston in the cylinder portion. 、 In the oil tank The hydraulic pump has a motor case that surrounds and covers the motor, one end of the oil tank is engaged and fixed to the motor case, and the other end is engaged and fixed to the hydraulic pump, the reducer is disposed inside the oil tank, and the end of the motor case opposite to the drive shaft of the motor protrudes from the oil tank. The present invention is characterized by the following configuration.

[0008] This configuration prevents the motor from becoming too hot and reducing its operating efficiency by absorbing the exhaust heat from the motor with the hydraulic oil in the oil tank. Furthermore, since the hydraulic oil for the hydraulic pump in the main body is used, the number of parts can be reduced and the system can be made smaller and lighter. Furthermore, the viscosity of the hydraulic oil can be reduced by raising the temperature of the hydraulic oil using the exhaust heat from the motor, enabling more efficient hydraulic operation even in low-temperature environments.

[0009] Power is supplied to the motor using one or more of a secondary battery, a DC power connection cable, an AC adapter, or a commercial power connection cable, depending on the type of motor. One example is a configuration that includes a secondary battery that supplies power to the motor and an adapter that connects the secondary battery to the main body. This configuration eliminates the need for a power cord, expanding the range of operation. For example, connecting the secondary battery as a battery pack to the adapter can easily extend the usable time.

[0010] The motor is preferably a brushless motor. This configuration reduces electromagnetic noise, achieves a longer life, and high efficiency, and allows for easy speed control. Here, the terms "brushless motor" and "permanent magnet synchronous motor" are synonymous. As an example, the motor is connected to the hydraulic pump via a reducer. This makes it easy to rotate the brushless motor at high speed while generating high power via the reducer. The reducer is disposed within the oil tank, and the hydraulic oil in the oil tank absorbs the exhaust heat from the reducer, thereby achieving good operating efficiency in the combination of the brushless motor and the reducer and easily achieving quieter operation. A magnetic filter is disposed within the oil tank, which facilitates lubrication of the reducer and removal of wear debris from the reducer.

[0011] As an example, the motor case of the motor is provided with fins that are configured to be in contact with the hydraulic oil in the oil tank. This configuration makes it easy to increase the surface area of ​​the motor case and improve heat dissipation efficiency. The fin pitch of the fins is set to a pitch that creates gaps through which the hydraulic oil can pass. The fins are made of aluminum, iron, brass, or a known alloy, and are subjected to surface treatment such as anodizing as necessary.

[0012] As an example, one end of the oil tank is in contact with the outer peripheral surface of the motor case. As an example, the hydraulic oil in the oil tank is able to come into contact with the outer peripheral surface of the motor case. As an example, the oil tank is configured to cover an area that is 0.5 times or more the axial length of the outer peripheral surface of the motor case. As an example, the hydraulic oil in the oil tank is able to come into contact with an area that is 0.5 times or more the axial length of the outer peripheral surface of the motor case. As an example, the side of the motor case opposite the drive shaft side is configured to protrude from the oil tank. As an example, the side of the motor case opposite the drive shaft side is configured not to come into contact with the hydraulic oil in the oil tank. As an example, the power supply line in the motor is configured not to come into contact with the hydraulic oil in the oil tank.

[0013] For example, one end of the oil tank is attached to the motor case, and the other end is attached to the hydraulic pump. This configuration allows the hydraulic oil to absorb the heat emitted from the motor more reliably while reducing the amount of hydraulic oil. The center of gravity can be positioned close to the handle that the operator holds, making the tank small, lightweight, and easy to hold.

[0014] For example, the hydraulic pump includes a swash plate cam that rotates around an axis passing through the drive shaft of the motor, multiple plungers arranged around an axis passing through the drive shaft in the cylinder unit and reciprocating while contacting the swash plate cam, and a check valve, and the hydraulic oil is delivered from the oil tank to the cylinder unit via the check valve. This configuration allows the hydraulic oil to be linearly increased in pressure in accordance with the rotational speed of the swash plate cam, facilitating operation control of the tool head. For example, a first conduit for delivering the hydraulic oil from the oil tank to the cylinder unit is formed at a connection between the hydraulic pump and the cylinder unit, and a check valve is provided in the first conduit. For example, a second conduit for returning the hydraulic oil from the cylinder unit to the hydraulic pump is formed at a connection between the hydraulic pump and the cylinder unit, and a return valve is provided in the second conduit. As an example, a third pipeline is formed at the connection between the hydraulic pump and the cylinder portion to return the hydraulic oil from the cylinder portion to the hydraulic pump, and as an example, a relief valve is provided midway along the third pipeline. [Effects of the Invention]

[0015] According to the present invention, it is possible to realize a small, lightweight hydraulic power tool that can reduce power consumption and perform work for long periods of time while preventing the motor from becoming too hot and reducing its operating efficiency. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic side view showing an example of a power tool according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the internal structure of the power tool of FIG. [Figure 3] 3A is a schematic cross-sectional view showing the internal structure of the drive system in the power tool of FIG. 1 from the side, FIG. 3B is a schematic cross-sectional view showing the internal structure of the drive system in the power tool of FIG. 1 from the top, FIG. 3C is a cross-sectional view taken along line CC in FIG. 3B, and FIG. 3D is a partial cross-sectional view of FIG. 3B when viewed from a different angle. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The embodiment is an electric tool 1 such as an electric cutter, an electric compressor, or an electric crimping machine. In all the drawings used to explain the embodiment, components having the same functions are designated by the same reference numerals, and repeated description of such components may be omitted.

[0018] 1 and 2 are schematic diagrams illustrating an example of a power tool 1 according to this embodiment. The power tool 1 is a cordless hydraulic power tool that includes a main body 2, a tool head 9 that is connected to the main body 2 and operates by the pressing force of a piston 4a in a cylinder portion 4 of the main body 2, and a secondary battery 5b that supplies power to a motor 8 of the main body 2. The piston 4a reciprocates along an axis P1 of a drive shaft 8a of the motor 8. That is, the piston 4a advances in the direction indicated by the Y arrow in the figure and retreats in the direction opposite the Y arrow in the figure. FIG. 1 illustrates an example of the power tool 1 equipped with a tool head 9 for an electric compressor. The power tool 1 may be a dedicated tool with a directly connected tool head 9 or a multi-function tool with an interchangeable tool head 9. To facilitate the explanation of the relative positions of the various components of the power tool 1, the X, Y, and Z arrows are used to indicate the directions. Note that the power tool 1 operates normally in any orientation.

[0019] 2 and 3A to 3C, the main body 2 has a cylinder section 4, a hydraulic pump 7 that is connected to the cylinder section 4 and has an integral structure, and an oil tank 3 that is attached to the outside of the hydraulic pump 7 and to the outside of the motor 8. The cylinder section 4 has a piston 4a disposed in a piston chamber 4b, and a coil spring 4c disposed along the outer periphery of the piston 4a in alignment with the axis of the piston 4a. The hydraulic pump 7 sends hydraulic oil 3c stored in the oil tank 3 to the piston chamber 4b of the cylinder section 4.

[0020] The main body 2 includes a motor 8 connected to the hydraulic pump 7 via a reducer 6 to drive the hydraulic pump 7, and a control circuit 27 for controlling the operation of the motor 8. A secondary battery 5b, which supplies power to the motor 8 and the control circuit 27, is connected as a battery pack to an adapter 5a of the main body 2. The adapter 5a is connected to the rear end of the main body 2. The tool head 9, main body 2, adapter 5a, and secondary battery 5b are arranged in this order along the axis P1. A handle 2d, which serves as a handle to be held by an operator, is integrally formed with the housing 2a of the main body 2 at the center of the main body 2 along the axis P1. The handle 2d is equipped with a start switch 2c for starting the motor 8 to send hydraulic oil 3c stored in the oil tank 3 to the cylinder 4, and a return switch 2e for returning the hydraulic oil 3c from the cylinder 4 to the oil tank 3. In this example, a battery pack composed of a secondary battery 5b, such as a lithium-ion battery or a nickel-metal hydride battery, is connected to the adapter 5a of the main body 2, and the adapter 5a is connected to the main body 2. This configuration makes the power tool 1 highly portable.

[0021] As an example, the motor 8 is an inner rotor type brushless motor. As an example, a motor case 8c of the motor 8 is provided with fins 8d for heat dissipation, and the fins 8d are configured to be able to come into contact with the hydraulic oil 3c stored in the oil tank 3.

[0022] 3A, the hydraulic pump 7 has a swash plate cam 7a that is connected to a drive shaft 8a of a motor 8 to which a reducer 6 is directly connected, or to the drive shaft 8a of a motor 8 that has a reducer 6 and is rotated by the driving force of the motor 8, and a plurality of plungers 12 that are arranged around an axis P1 passing through the drive shaft 8a in the cylinder section 4 and that reciprocate while in contact with the swash plate cam 7a. A check valve 16 that prevents backflow of hydraulic oil 3c from the plungers 12 to the oil tank 3 is arranged on the secondary side of the plungers 12 at a position close to the hydraulic pump 7 (the position on the cross section of line CC).

[0023] The oil tank 3 is a bag-shaped body made of an oil-resistant, expandable and contractible rubber material. The oil tank 3 is engaged with both the hydraulic pump 7 and the motor 8, and the motor case 8c is covered by the oil tank 3. As shown in FIGS. 3A to 3D, a first pipe 21 is formed at the connection between the hydraulic pump 7 and the cylinder 4 to send hydraulic oil 3c from the oil tank 3 to the cylinder 4, and a check valve 15 is provided along the first pipe 21. A second pipe 22 is formed at the connection between the hydraulic pump 7 and the cylinder 4 to return hydraulic oil 3c from the cylinder 4 to the hydraulic pump 7, and a return valve 26 is provided along the second pipe 22. A third pipe 23 is formed at the connection between the hydraulic pump 7 and the cylinder 4 to return hydraulic oil 3c from the cylinder 4 to the hydraulic pump 7, and a relief valve 25 is provided along the third pipe 23.

[0024] The oil tank 3 has one end 3a that is engaged with the motor case 8c and the other end 3b that is engaged with the hydraulic pump 7. As an example, the one end 3a of the oil tank 3 is curled outward and is engaged and fixed in an outer circumferential groove of the motor case 8c by a first locking member 17a, such as a rubber ring such as an O-ring or a cable tie. Similarly, the other end 3b of the oil tank 3 is curled outward and is engaged and fixed in an outer circumferential groove of the hydraulic pump 7 by a second locking member 17b, such as a rubber ring such as an O-ring or a cable tie.

[0025] According to this embodiment, the hydraulic oil 3c inside the oil tank 3 is configured to absorb the waste heat from the motor 8 and the reducer 6, which prevents the motor 8 and the reducer 6 from becoming too hot and reducing their operating efficiency. In addition, since the existing hydraulic oil 3c is used in the main body 2, the number of parts can be reduced without increasing, making the device compact and lightweight. Furthermore, by using the waste heat from the motor 8 and the reducer 6 to increase the temperature of the hydraulic oil 3c, the viscosity of the hydraulic oil 3c can be reduced even in a low-temperature environment, resulting in a configuration that enables more efficient hydraulic operation.

[0026] For example, the tool head 9 performs a gripping operation, a provisional gripping operation, or a gripping preparation operation at a low-pressure stage up to a first pressure, and performs a compression operation or a crimping operation at a high-pressure stage up to a second pressure. When the predetermined operation by the tool head 9 is completed, the relief valve 25 opens and reduces the pressure in the cylinder portion 4. To return the piston 4a to its original position, the return pin 28 is operated to open the return valve 26, and the restoring force of the coil spring 4c returns the hydraulic oil 3c to the oil tank 3. The power tool 1 may have an automatic return function, and in a configuration with this function, when the predetermined operation by the tool head 9 is completed, the tool head 9 returns to its state before the operation.

[0027] The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the scope of the present invention. [Explanation of symbols]

[0028] 1 Power tools 2 Main body, 2a Housing, 2c Start switch, 2d Handle, 2e Return switch 3 Oil tank, 3a one end side, 3b other end side, 3c hydraulic oil 4 cylinder portion, 4a piston, 4b piston chamber, 4c coil spring 5a Adapter, 5b Secondary battery (battery pack) 6 Reducer 7 Hydraulic pump, 7a Swash plate cam 8 motor, 8a drive shaft, 8c motor case, 8d fin 9 Tool Head 12 Plunger 16 Check valve 17a first locking member, 17b second locking member 21 1st pipeline 22 2nd pipeline 23 3rd pipeline 25 Relief valve 26 Return valve 27 Control circuit 28 Return pin P1 axis

Claims

1. An electric power tool comprising: a cylinder section, an oil tank, a hydraulic pump that sends hydraulic oil from the oil tank to the cylinder section, a reducer connected to the hydraulic pump, a main body having a motor directly connected to the reducer to drive the hydraulic pump, and a tool head that is connected to the main body and is actuated by the pressing force of a piston in the cylinder section, the electric power tool having a motor case that is surrounded by the oil tank and covers the motor, one end of the oil tank is engaged and fixed to the motor case and the other end is engaged and fixed to the hydraulic pump, the reducer is disposed inside the oil tank, and the opposite side of the motor case from the drive shaft of the motor protrudes from the oil tank. A power tool characterized by:

2. The hydraulic pump has a swash plate cam that rotates around an axis passing through the drive shaft, a plurality of plungers that are arranged around the axis passing through the drive shaft in the cylinder section and reciprocate while contacting the swash plate cam, and a check valve, and is configured to send the hydraulic oil from the oil tank to the cylinder section via the check valve. The power tool according to claim 1 .

3. A secondary battery that supplies power to the motor and an adapter that connects the secondary battery to the main body are provided. The power tool according to claim 1 or 2,

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