power tools

Abstract

To provide an electric tool with a structure that can be more efficiently boosted than before by controlling a rotation speed of a motor so as to send a working fluid according to liquid sending operation of a hydraulic pump, according to a state of the working fluid such as temperature or viscosity.SOLUTION: An electric tool 1 includes: a cylinder portion 4; an oil tank 3; a body portion 2 that is provided with a hydraulic pump 7a sending a working fluid 3a to the cylinder portion 4, a motor 7b driving the hydraulic pump 7a, and a control circuit 7c; a tool head 8 that is operated by a piston 4a while being coupled to the body portion 2; a secondary battery 6 that supplies power to the motor 7b; and a sensor 9 that detects a state of the working fluid 3a. The control circuit 7c drive-controls the motor 7b on the basis of a detection signal from the sensor 9.SELECTED DRAWING: Figure 1

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 using a power tool in a cold environment, the tool body may be cold. Hydraulic oil has the property of increasing viscosity as the temperature drops. It has recently been discovered that if the motor speed is increased when the viscosity of the hydraulic oil is high, the hydraulic oil will not be pumped as expected by the hydraulic pump, resulting in a longer pressure build-up 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 power tool configured to be able to increase pressure more efficiently than conventional tools by controlling the motor rotation speed so that hydraulic oil is pumped in accordance with the hydraulic pump's pumping operation, depending on the state of the hydraulic oil, such as temperature and viscosity.

[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 having a piston, an oil tank, a hydraulic pump that sends hydraulic oil from the oil tank to the cylinder portion, a motor that drives the hydraulic pump, a main body portion having a control circuit disposed therein, a tool head that is connected to the main body portion and operated by the piston, a secondary battery that supplies power to the motor, and a sensor that detects the temperature of the hydraulic oil, and the control circuit receives a detection signal from the sensor and detects the temperature of the hydraulic oil. than room temperature When it is determined that the rotation speed is low, the rotation speed of the motor is reduced below a set value.

[0008] With this configuration, the control circuit controls the motor based on the detection signal from the sensor that detects the state of the hydraulic oil, so the pressure can be increased more efficiently, shortening the time required for pressure increase compared to conventional tools. In addition, efficient operation extends the battery life.

[0009] The sensor is preferably one or more of a temperature sensor, a viscosity sensor, a flow rate sensor, and a pressure sensor. In the case of a temperature sensor, by intentionally reducing the rotation speed of the motor when the temperature of the hydraulic oil is low, the hydraulic oil can be delivered in accordance with the hydraulic pump's delivery operation. In the case of a viscosity sensor, by intentionally reducing the rotation speed of the motor when the viscosity of the hydraulic oil is high, the hydraulic oil can be delivered in accordance with the hydraulic pump's delivery operation. In the case of a flow rate sensor, by intentionally reducing the rotation speed of the motor when the flow rate of the hydraulic oil is lower than a set value, the hydraulic oil can be delivered in accordance with the hydraulic pump's delivery operation. In the case of a pressure sensor, by intentionally reducing the rotation speed of the motor when the pressure rise of the hydraulic oil is slower than a set value, the hydraulic oil can be delivered in accordance with the hydraulic pump's delivery operation.

[0010] As an example, the control circuit calculates the temperature of the hydraulic oil based on the detection signal, and when the calculated temperature of the hydraulic oil is lower than a reference value, the rotation speed of the motor is reduced below a set value. The motor can be a brushless motor, a carbon brush motor, a universal motor, or any other known electric motor. In the case of a brushless motor, the rotor position can be detected using a Hall element, and the rotation speed can be controlled by an inverter. In the case of a carbon brush motor or a universal motor, the rotation speed can be controlled by linear control, which increases the input voltage value in response to a temperature rise; pulse control, which increases the duty ratio of the input voltage pulse in response to a temperature rise; or voltage switching control, which switches the input voltage value when the temperature reaches a set value.

[0011] It is more preferable that the sensor is a contact temperature sensor, which allows for a simple configuration and makes it easy to accommodate the sensor within the main body.

[0012] For example, the sensor may be disposed inside the oil tank. This allows the state of the hydraulic oil to be directly detected, facilitating highly accurate control. For example, the sensor may be attached to a metal part of the oil tank.

[0013] As an example, the sensor is configured to be in contact with the outside of the oil tank, which allows the oil tank to have an existing configuration and the sensor to be retrofitted, making assembly and maintenance easy.

[0014] For example, the sensor is configured to be in contact with the outside of the cylinder portion. This allows the cylinder portion to have an existing configuration and the sensor to be retrofitted, making assembly and maintenance easy. For example, the sensor is attached to a metal part of the cylinder portion.

[0015] As an example, the sensor is configured to be disposed within the cylinder portion. This allows the oil tank to have its existing configuration while directly detecting the state of the hydraulic oil, making it easy to achieve highly accurate control. As an example, a first conduit for delivering the hydraulic oil is formed within the cylinder portion, and the sensor is configured to be disposed within a second conduit connected to the first conduit. This allows the state of the hydraulic oil to be directly detected while maintaining the flow of hydraulic oil, making it easy to achieve highly accurate control.

[0016] For example, a battery pack including a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery is connected to an adapter of the main body, and the adapter is connected to the handle of the main body, making the power tool highly portable. [Effects of the Invention]

[0017] According to the present invention, by controlling the motor rotation speed so that the hydraulic oil is pumped in accordance with the hydraulic pump's pumping operation depending on the state of the hydraulic oil, such as temperature and viscosity, it is possible to create an electric tool that is capable of increasing pressure more efficiently than conventional tools. [Brief explanation of the drawings]

[0018] [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] Figure 2A is a schematic structural diagram showing a first example of sensor arrangement in the power tool shown in Figure 1, Figure 2B is a schematic structural diagram showing a second example of sensor arrangement in the power tool shown in Figure 1, Figure 2C is a schematic structural diagram showing a third example of sensor arrangement in the power tool shown in Figure 1, and Figure 2D is a schematic structural diagram showing the third example of sensor arrangement in the power tool shown in Figure 1. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The embodiment is an electric compressor, an electric crimping machine, an electric cutter, or any other known hydraulic power tool. In all drawings used to explain the embodiment, components having the same function are designated by the same reference numerals, and repeated description thereof may be omitted.

[0020] FIG. 1 is a schematic diagram illustrating an example of a power tool 1 according to this embodiment. The power tool 1 includes a main body 2, a tool head 8 connected to the main body 2 and operated by a piston 4a in a cylinder 4 of the main body 2, and a secondary battery 6 that supplies power to the motor 7b of the main body 2. The power tool 1 is a cordless tool that is handheld and used by a worker on-site. To facilitate understanding of the relative positions of the various components of the power tool 1, arrows X, Y, and Z are used to indicate the directions. The piston 4a reciprocates along a first axis P1. That is, the piston 4a advances toward the Y-direction arrow in the drawing and retreats toward the opposite side of the Y-direction arrow in the drawing. The example shown in FIG. 1 is a tool head 8 for an electric compressor, and is a multi-function power tool 1 that allows the tool head 8 to be replaced. The power tool 1 operates normally in any orientation during work.

[0021] The main body 2 includes a cylinder 4 having a piston 4a disposed in a piston chamber 4b, an oil tank 3 attached to the outside of the cylinder 4 near the hydraulic pump 7a, a hydraulic pump 7a connected to the cylinder 4 to deliver hydraulic oil 3a from the oil tank 3 to the piston chamber 4b of the cylinder 4, a motor 7b connected to the hydraulic pump 7a to drive the hydraulic pump 7a, and a control circuit 7c for controlling the operation of the motor 7b. A secondary battery 6, which supplies power to the motor 7b and the control circuit 7c, is connected to an adapter 5 of the main body 2 as a battery pack, and 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 is equipped with a start switch 2c. In this embodiment, a sensor 9 that detects the state of the hydraulic oil 3a is disposed in the main body 2, and the control circuit 7c controls the operation of the motor 7b based on a detection signal from the sensor 9.

[0022] As an example, the hydraulic pump 7a is a swash plate type piston pump having a swash plate cam rotated by the drive shaft of the motor 7b. The piston chamber 4b of the cylinder portion 4 and the hydraulic pump 7a are connected by the cylinder portion 4, and a first pipe 11 for delivering the hydraulic oil 3a is formed inside the cylinder portion 4.

[0023] As an example, the control circuit 7c is configured to calculate the temperature of the hydraulic oil 3a based on the detection signal of the contact-type temperature sensor 9, and to reduce the rotation speed of the motor 7b below a set value when the calculated value is lower than a reference value. Also, the control circuit 7c is configured to calculate the temperature of the hydraulic oil 3a based on the detection signal of the contact-type temperature sensor 9, and to increase the rotation speed of the motor 7b above the set value when the calculated value is higher than a reference value.

[0024] [Example 1] 2A is a schematic structural diagram showing a first example of sensor arrangement in the power tool 1. The temperature sensor 9 is arranged inside the oil tank 3. As an example, the temperature sensor 9 is attached to a metal part of the oil tank 3. This allows the state of the hydraulic oil 3a to be directly detected, facilitating highly accurate control.

[0025] [Example 2] 2B is a schematic structural diagram showing a second example of sensor placement in the power tool 1. The temperature sensor 9 is arranged in contact with the outside of the oil tank 3. As an example, the temperature sensor 9 is attached to a metal part of the oil tank 3. This allows the oil tank 3 to have an existing configuration and the temperature sensor 9 to be retrofitted, making assembly and maintenance easy.

[0026] [Example 3] 2C is a schematic structural diagram showing a third example of sensor placement in the power tool 1. The temperature sensor 9 is arranged in contact with the outside of the cylinder portion 4. As an example, the temperature sensor 9 is attached to a metal part of the cylinder portion 4. This allows the oil tank 3 and cylinder portion 4 to have an existing configuration and the temperature sensor 9 to be retrofitted, making assembly and maintenance easy.

[0027] [Example 4] 2D is a schematic structural diagram showing a fourth example of sensor arrangement in the power tool 1. A first pipe 11 for delivering the hydraulic oil 3a and a second pipe 12 for attaching the temperature sensor 9 are each formed inside the cylinder portion 4, the first pipe 11 and the second pipe 12 are connected by a pipe connection portion 13, and the temperature sensor 9 is disposed inside the second pipe 12. This allows the state of the hydraulic oil 3a to be directly detected while maintaining the flow of the hydraulic oil 3a, facilitating highly accurate control.

[0028] In the above example, a configuration in which a temperature sensor is used as the sensor 9 to control the drive of the motor 7b has been described, but the present invention is not limited to this example. In this embodiment, not only a temperature sensor but also a viscosity sensor, a flow rate sensor, a pressure sensor, etc. can be applied as the sensor 9. Furthermore, the sensor 9 may be a combination of two or more types of sensors that detect different physical quantities. Alternatively, the sensor 9 may be a combination of two or more sensors of the same type.

[0029] In the above example, the secondary battery 6 is detachably attached to the main body 2 in the form of a battery pack, but the present invention is not limited to this example. In this embodiment, the secondary battery 6 may be built-in, or a combination of these may be used.

[0030] 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]

[0031] 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 5 Adapters 6 Secondary battery 7a hydraulic pump, 7b motor, 7c control circuit 8 Tool Head 9 Sensors 11 1st pipeline 12 2nd pipeline 13 Pipe connection P1 1st axis

Claims

[Claim 1] The tool includes a cylinder portion having a piston, an oil tank, a hydraulic pump that sends hydraulic oil from the oil tank to the cylinder portion, a motor that drives the hydraulic pump, a main body portion in which a control circuit is disposed, a tool head that is connected to the main body portion and is operated by the piston, a secondary battery that supplies power to the motor, and a sensor that detects the temperature of the hydraulic oil, and the control circuit receives a detection signal from the sensor and, when it determines that the temperature of the hydraulic oil is lower than room temperature, reduces the rotation speed of the motor below a set value. A power tool characterized by:

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