Power Tools

Abstract

To provide a power tool configured to suppress burden on a motor and increase hydraulic oil pressure slowly so that operation time can be shortened.SOLUTION: A power tool 1 comprises: a body part 2 that includes a cylinder part 4, an oil tank 3, a hydraulic pump 7 for sending a hydraulic oil 3a to the cylinder part 4 and a motor 8 for driving the hydraulic pump 7; a tool head 9 that operates with a pressing force from a piston 4a while being connected to the body part 2; and a battery 6 for providing electric power to the motor 8. The hydraulic pump 7 comprises: a swash cam 7a connected to the driving shaft 8a of the motor 8; a first plunger 11 and a second plunger 12 that are arranged around an axis line P1 running through the driving shaft 8a in the cylinder part 4 and conduct reciprocating motion while touching the swash cam 7a; and a check valve 15 that opens to the secondary side of the first plunger 11 under a first pressure. The first liquid amount to be supplied by the first plunger 11 is larger than the second liquid amount to be supplied by the second plunger 12 until the first pressure is reached.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] 2. Description of the Related Art Hydraulic power tools are known in the art (Patent Literature 1: JP 2018-086696 A). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-086696 A Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional products, the battery tends to wear out quickly when the tool head is repeatedly operated in a short time, such as compression or crimping. Since the maximum current that can be passed through the motor is predetermined by the battery rating, the market demands efficient operation while reducing the load on the motor in order to reduce battery consumption and perform long-term work. In addition, the market demands a rapid increase in hydraulic pressure from low to high pressure to shorten work time in order to repeat the tool head operation in a short time. [Means for solving the problem]

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide an electric tool that can operate efficiently while reducing the load on the motor, consumes less battery power than conventional products, and can quickly increase the hydraulic pressure from low to high to shorten working time.

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

[0007] The electric tool according to the present invention includes a cylinder section, an oil tank, a hydraulic pump that delivers hydraulic oil in the oil tank to the cylinder section, a main body having a motor that drives the hydraulic pump, a tool head that is connected to the main body and operates by the pressing force of a piston in the cylinder section, and a battery that supplies power to the motor. The hydraulic pump has a swash plate cam that is connected to a drive shaft of the motor and rotates, and a plurality of plungers that are arranged around an axis passing through the drive shaft in the cylinder section and reciprocate while in contact with the swash plate cam. A first plunger of the plungers has a check valve on its secondary side that opens at a first pressure, and a second plunger of the plungers does not have the check valve on its secondary side, and a relief valve that opens at a second pressure higher than the first pressure is arranged in the cylinder section. Until the first pressure is reached, the first amount of fluid delivered by the first plunger is increased more than the second amount of fluid delivered by the second plunger.

[0008] According to this configuration, the amount of fluid sent by the first plunger and the second plunger at the low pressure stage is increased, and the transition time to the high pressure stage can be shortened. Furthermore, the load on the motor at the high pressure stage can be suppressed, and the maximum current value of the battery can be reduced. Therefore, the hydraulic pressure can be quickly increased from low pressure to high pressure, and the operation time can be shortened.

[0009] As an example, the product of the plunger stroke L1, the plunger cross-sectional area S1, and the number of plungers N1 in the first plunger is larger than the product of the plunger stroke L2, the plunger cross-sectional area S2, and the number of plungers N2 in the second plunger. With this configuration, the hydraulic pressure can be quickly increased from low to high pressure while maintaining a small size suitable for an electric tool, thereby shortening the working time.

[0010] As an example, a battery pack including a lithium-ion battery, a nickel-metal hydride battery, or the like is connected to an adapter of the main body, and the adapter is connected to a handle of the main body. This configuration makes it possible to make a power tool with excellent portability. Effect of the Invention

[0011] According to the present invention, it is possible to provide an electric tool that can operate efficiently while reducing the load on the motor, consumes less battery power than conventional products, and quickly increases the hydraulic pressure from low to high to shorten working time. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic side view showing an example of a power tool according to an embodiment of the present invention. [Diagram 2] 2A is a schematic cross-sectional view showing a first example of the power tool shown in FIG. 1, FIG. 2B is a schematic cross-sectional view taken along line BB in FIG. 2A, and FIG. 2C is a schematic view of FIG. 2A viewed from direction C. [Diagram 3] 3A is a schematic cross-sectional view showing an example of the arrangement of a first plunger in the first example of the power tool shown in FIG. 1, and FIG. 3B is a schematic cross-sectional view showing an example of the arrangement of a second plunger in the first example of the power tool shown in FIG. 1. [Figure 4] FIG. 4 is a schematic cross-sectional view showing a first example of the power tool shown in FIG. [Diagram 5] 5A is a schematic cross-sectional view showing a second example of the power tool shown in FIG. 1, and FIG. 5B is a schematic cross-sectional view showing a third example of the power tool shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] 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 compressor, an electric crimping machine, an electric cutter, etc. In all the drawings for explaining the embodiment, members having the same functions are given the same reference numerals, and repeated explanations thereof may be omitted.

[0014] FIG. 1 is a schematic diagram showing an example of an electric power tool 1 according to the present embodiment. The electric power tool 1 is a cordless type 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 part 4 of the main body 2, and a battery 6 that supplies power to a motor 8 of the main body 2, and is used by a worker at a work site. The piston 4a reciprocates along an axis P1 of a drive shaft 8a of the motor 8. That is, the piston 4a advances toward the side of the Y direction arrow in the figure, and retreats toward the opposite side of the Y direction arrow in the figure. The example in FIG. 1 is a tool head 9 of an electric compressor, and is a multi-function electric power tool 1 in which the tool head 9 is replaced. Here, in order to easily explain the positional relationship of each part of the electric power tool 1, directions are indicated by X, Y, and Z arrows in the figure. The electric power tool 1 operates normally in any direction.

[0015] The main body 2 has a cylinder 4, a hydraulic pump 7 connected to the cylinder 4 and integrally formed, and an oil tank 3 attached to the outside of the hydraulic pump 7 and connected to the cylinder 4. The cylinder 4 has a piston 4a arranged in a piston chamber 4b, and a coil spring 4c arranged along the outer periphery of the piston 4a in accordance with the axis of the piston 4a. The hydraulic pump 7 sends the hydraulic oil 3a stored in the oil tank 3 to the piston chamber 4b of the cylinder 4. The main body 2 also has a motor 8 connected to the hydraulic pump 7 for driving the hydraulic pump 7, and a control circuit 27 for controlling the drive of the motor 8. A battery 6 for supplying power to the motor 8 and the control circuit 27 is connected to an adapter 5 of the main body 2. The adapter 5 is connected to a handle 2d of the main body 2. The handle 2d is a handle that is held by an operator, and has a start switch 2c arranged therein. As an example, a battery pack constituted by a battery 6 such as a lithium ion battery or a nickel metal hydride battery is connected to an adapter 5 of the main body 2, and the adapter 5 is connected to the handle 2d of the main body 2. This configuration makes the power tool 1 highly portable.

[0016] Fig. 2A is a schematic cross-sectional view showing the structure of the hydraulic pump 7 in the power tool 1, Fig. 2B is a schematic cross-sectional view of the line BB in Fig. 2A, and Fig. 2C is a schematic view of Fig. 2A viewed from the direction C. Fig. 3A is a schematic cross-sectional view showing an example of the arrangement of the first plunger 11 in the hydraulic pump 7 of the power tool 1, and Fig. 3B is a schematic cross-sectional view showing an example of the arrangement of the second plunger 12 in the hydraulic pump 7 of the power tool 1. Fig. 4 is a schematic cross-sectional view of the power tool 1 viewed from a different direction from the above. The power tool 1 of this embodiment has a swash plate cam 7a connected to the drive shaft 8a of the motor 8 and rotated by the driving force of the motor 8, and a first plunger 11 and a second plunger 12 arranged around an axis P1 passing through the drive shaft 8a in the cylinder section 4 and reciprocating while contacting the swash plate cam 7a.

[0017] The oil tank 3 is disposed at a position connecting the cylinder portion 4 and the hydraulic pump 7. The oil tank 3 communicates with the hydraulic pump 7 via a check valve 15. In addition, the oil tank 3 communicates with the cylinder portion 4 via a relief valve 26.

[0018] 3A, a check valve 25 for preventing backflow of the hydraulic oil 3a from the first plunger 11 to the oil tank 3 is disposed at a position on the secondary side of the first plunger 11 that communicates with the piston chamber 4b. Also, at a position (position of the cross section of line BB) closer to the hydraulic pump 7 than the position where the check valve 25 is disposed on the secondary side of the first plunger 11, a check valve 15 that opens when the pressure is equal to or higher than the first pressure, which is a specified pressure, and a check valve 16 for preventing backflow of the hydraulic oil 3a to the first plunger 11 are disposed.

[0019] 3B, a check valve 25 for preventing backflow of the hydraulic oil 3a to the second plunger 12 is disposed at a position on the secondary side of the second plunger 12 that communicates with the piston chamber 4b. Also, a check valve 16 for preventing backflow of the hydraulic oil 3a from the second plunger 12 to the oil tank 3 is disposed at a position (position of the cross section of line BB) closer to the hydraulic pump 7 than the position where the check valve 25 is disposed on the secondary side of the second plunger 12. No check valve 15 is disposed on the secondary side of the second plunger 12.

[0020] As shown in FIG. 3A and FIG. 3B, a first flow path 21 for feeding the hydraulic oil 3a by the reciprocating motion of the first plunger 11 and a second flow path 22 for feeding the hydraulic oil 3a by the reciprocating motion of the second plunger 12 are formed inside the cylinder portion 4. In the first example, the first plunger 11 reciprocates along a first center line P11 parallel to the axis line P1 passing through the drive shaft 8a, and the second plunger 12 reciprocates along a second center line P12 parallel to the axis line P1 passing through the drive shaft 8a. Also, as shown in FIG. 4, a relief valve 26 for releasing the pressure in the piston chamber 4b by releasing the hydraulic oil 3a in the high pressure stage is disposed in the cylinder portion 4. The relief valve 26 is, for example, a direct acting relief valve. A return flow path 28 for returning the hydraulic oil 3a to the oil tank 3 through the relief valve 26 is formed inside the cylinder portion 4.

[0021] The first plunger 11 delivers the hydraulic oil 3a to the cylinder section 4 until the pressure reaches the first pressure, which is lower than the second pressure, but when the pressure reaches or exceeds the first pressure, the check valve 15 opens and the hydraulic oil 3a is no longer delivered to the cylinder section 4. In other words, when the pressure reaches or exceeds the first pressure, the hydraulic oil 3a returns from the first plunger 11 through the check valve 15 to the oil tank 3. The second plunger 12 delivers the hydraulic oil 3a to the cylinder section 4 both in the stages of reaching the first pressure and the stage of reaching the second pressure.

[0022] As an example, the tool head 9 performs a gripping operation, a temporary 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. Then, when a predetermined operation by the tool head 9 is completed, the hydraulic oil 3a returns to the oil tank 3 from the cylinder portion 4 through the relief valve 26. The power tool 1 may have an automatic return function, and in a configuration having the automatic return function, when a predetermined operation by the tool head 9 is completed, the tool head 9 returns to the state before the operation.

[0023] A first example will be described below with reference to Figures 3A and 3B.

[0024] In the first example, the distance W1 from the axis P1 to the first plunger 11 is made larger than the distance W2 from the axis P1 to the second plunger 12, so that the plunger stroke L1 of the first plunger 11 is made larger than the plunger stroke L2 of the second plunger 12. Here, the plunger cross-sectional area S1 of the first plunger 11 is the same as the plunger cross-sectional area S2 of the second plunger 12. In addition, the number of plungers N1 of the first plunger 11 is 2, and the number of plungers N2 of the second plunger 12 is 2. Therefore, the amount of liquid delivered per one rotation of the swash plate cam 7a in the low pressure stage up to the first pressure is a first amount of liquid delivered by the first plunger 11 that is larger than the second amount of liquid delivered by the second plunger 12.

[0025] This configuration increases the amount of fluid sent by the first plunger 11 and the second plunger 12 in the low pressure stage up to the first pressure, shortening the transition time to the high pressure stage. Furthermore, the load on the motor 8 in the high pressure stage can be reduced, making it possible to reduce the maximum current value of the battery 6. In other words, the hydraulic pressure can be quickly increased from low pressure to high pressure, shortening the operation time. Furthermore, the battery 6 lasts longer due to the rational operation. As an example, in a configuration using a battery 6 with an output current in the range of 1 to 40 [A], it is easy to achieve a configuration that suppresses the consumption of the battery 6 and the rise in the battery temperature. Note that the above values ​​are merely examples and are not limited to the above values.

[0026] The first plunger 11 and the second plunger 12 are arranged around the axis P1 with a predetermined phase shift. In the example of Fig. 2C, the first plunger 11 and the second plunger 12 are arranged in pairs, and are arranged alternately around the axis P1 with a phase shift of 90 degrees. With this configuration, the pressure can be increased linearly in accordance with the rotation speed of the swash plate cam 7a, so that the operation of the tool head 9 can be easily controlled by the control circuit 27.

[0027] The axis P1 coincides with the center line of the piston 4a in the reciprocating direction. As an example, the interval W1 from the axis P1 to the first center line P11 in the reciprocating direction of the first plunger 11 is set to be 1.04 times or more and 1.12 times or less than the interval W2 from the axis P1 to the second center line P12 in the reciprocating direction of the second plunger 12. In addition, the plunger stroke L1 of the first plunger 11 is set to be 1.04 times or more and 1.12 times or less than the plunger stroke L2 of the second plunger 12. Note that the above numerical values ​​are merely examples and are not limited to the above numerical values. In any configuration, the effective diameter and effective angle of the swash plate cam 7a are set to fall within the ranges.

[0028] Next, a second example will be described below with reference to FIG. 5A.

[0029] In the second example, the plunger cross-sectional area S1 of the first plunger 11 is larger than the plunger cross-sectional area S2 of the second plunger 12. Here, the plunger stroke L1 of the first plunger 11 is the same as the plunger stroke L2 of the second plunger 12. The number of plungers N1 of the first plunger 11 is 2, and the number of plungers N2 of the second plunger 12 is 2. Therefore, the amount of liquid delivered per one rotation of the swash plate cam 7a in the low pressure stage up to the first pressure is such that the first amount of liquid delivered by the first plunger 11 is larger than the second amount of liquid delivered by the second plunger 12. Here, FIG. 5A is a schematic cross-sectional view showing the second example of the power tool shown in FIG. 1, and corresponds to FIG. 2B in the first example.

[0030] This configuration makes it easy to increase the amount of liquid delivered in the low pressure stage up to the first pressure. As an example, the plunger diameter is 4 to 10 mm, and preferably 4 to 6 mm. As an example, the plunger cross-sectional area S1 is set to be 1.2 to 6.6 times the plunger cross-sectional area S2. Note that the above values ​​are only examples and are not limited to the above values. In any configuration, the effective diameter and effective angle of the swash plate cam 7a are set within the range.

[0031] Next, a third example will be described below with reference to FIG. 5B.

[0032] In the third example, the number of plungers N1 in the first plunger 11 is 3, and the number of plungers N2 in the second plunger 12 is 1. Here, the plunger stroke L1 in the first plunger 11 is the same as the plunger stroke L2 in the second plunger 12. Also, the plunger cross-sectional area S1 in the first plunger 11 is the same as the plunger cross-sectional area S2 in the second plunger 12. Therefore, the amount of liquid delivered per one rotation of the swash plate cam 7a in the low pressure stage up to the first pressure is configured such that the first amount of liquid delivered by the first plunger 11 is larger than the second amount of liquid delivered by the second plunger 12. Here, FIG. 5B is a schematic cross-sectional view showing the third example of the power tool shown in FIG. 1, and corresponds to FIG. 2B in the first example.

[0033] This configuration makes it easy to increase the amount of liquid delivered in the low pressure stage up to the first pressure. As an example, the number of plungers N1=3 and the number of plungers N2=2. As an example, the number of plungers N1=3 and the number of plungers N2=1. As an example, the number of plungers N1=2 and the number of plungers N2=1. Note that these combinations are merely examples and are not limited to these combinations. In any configuration, the effective diameter and effective angle of the swash plate cam 7a are set to fall within the range.

[0034] In the above example, a total of four first plungers 11 and second plungers 12 are arranged around the axis P1 with their phases shifted at a predetermined interval, but the present invention is not limited to this example. For example, a total of two first plungers 11 and two second plungers 12 may be arranged. Also, for example, a configuration may be used in which the first plunger, the second plunger, and the third plunger are arranged around the axis P1 with their phases shifted at a predetermined interval.

[0035] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the scope of the present invention.

[0036] 1 Power tools 2 Main body, 2a Housing, 2c Start switch, 2d Handle 3 Oil tank, 3a hydraulic oil 4 cylinder portion, 4a piston, 4b piston chamber, 4c coil spring 5 Adapter 6 Battery 7 Hydraulic pump, 7a Swash plate cam 8 motor, 8a drive shaft 9 Tool Head 11 First plunger 12 Second plunger 15 Check valve 16 Check valve 21 First Channel 22 Second flow path 25 Check valve 26 Relief valve 27 Control circuit 28 Return flow path L1 Plunger stroke L2 Plunger stroke P1 axis

Claims

1. a main body having a cylinder section, an oil tank, a hydraulic pump that delivers hydraulic oil in the oil tank to the cylinder section, and a motor that drives the hydraulic pump; a tool head that is connected to the main body and operates by the pressing force of a piston in the cylinder section; and a battery that supplies power to the motor, wherein the hydraulic pump has a swash plate cam that is connected to a drive shaft of the motor and rotates, and a plurality of plungers that are arranged around an axis passing through the drive shaft in the cylinder section and reciprocate while in contact with the swash plate cam, a first of the plungers has a check valve on its secondary side that opens at a first pressure, a second of the plungers does not have the check valve on its secondary side, and a relief valve that opens at a second pressure higher than the first pressure is arranged in the cylinder section, A first amount of liquid delivered by the first plunger is made larger than a second amount of liquid delivered by the second plunger until the first pressure is reached. A power tool characterized by:

2. The product of the plunger stroke L1, the plunger cross-sectional area S1, and the number of plungers N1 in the first plunger is larger than the product of the plunger stroke L2, the plunger cross-sectional area S2, and the number of plungers N2 in the second plunger.

2. The power tool according to claim 1 .

3. The oil tank is connected to the hydraulic pump via the check valve, and the oil tank is connected to the cylinder portion via the relief valve.

3. The power tool according to claim 1 or 2,

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