EP3053705B1

EP3053705B1 - Power unit and electric tool

Info

Publication number: EP3053705B1
Application number: EP13894731.2A
Authority: EP
Inventors: Tadashi Tatai
Original assignee: Izumi Products Co
Current assignee: Maxell Izumi Co Ltd
Priority date: 2013-09-30
Filing date: 2013-09-30
Publication date: 2019-02-06
Anticipated expiration: 2033-09-30
Also published as: CN105555483A; CN105555483B; EP3053705A4; JP6040319B2; JPWO2015045161A1; WO2015045161A1; EP3053705A1

Description

The present invention relates to a power unit and an electric tool.
As an electric tool provided with a power unit for driving a hydraulic pump by rotating a motor by an electric power source of a battery pack is widespread because the electric tool can work even at a work place distant from the power source.
An electric tool rotationally drives a motor, using a battery pack having a built-in battery as a power source, generates a hydraulic pressure by operating a hydraulic pump by this rotational driving of the motor, and pressure-transports hydraulic oil to a hydraulic cylinder to thereby move a piston. An electric tool performs processing by a tool provided at the front end of the piston. As such an electric tool, there are known a cutting tool for cutting a thin wire, an electric wire, or the like, and as one used in connecting a crimping terminal to the end of an electric wire, a compressing tool disclosed by JP H8-150576A (fig. 1) and the like.
For example, a compressing tool is an electric tool that is provided with a movable die 7 at the tip end portion of a piston 6 (see FIG. 2) and provided with a fixing die 8 at a tool head 2. A work (for example, an electric wire and a crimping terminal) is disposed between the movable die 7 and the fixing die 8 so that the crimping tool crimps the work.
FIGS. 6A to 6C are configuration diagrams schematically showing the configuration of a conventional electric tool.
As shown in FIG. 6A, a conventional electric tool 30 is configured by an electric tool head 31 and a power unit 32. On the electric tool 30, a body 36 is integrally connected to the rear portion of the electric tool head 31, and the body 36 has a built-in returning device 25 for returning the position of a piston to an original position and a pressure restricting device 26. Further, one battery pack 14 and a motor 33 are attached on the rear portion of the body 36, and the battery pack 14 is electrically connected as the electric power source for rotational driving of the motor 33.
Still further, a hydraulic pump 35 for pressure-transporting hydraulic oil is attached to the power unit 32 through a deceleration mechanism 34 for decelerating the rotation of the motor 33.
As shown in FIG. 6B, a power unit 32a of the electric tool 30a is different from the above-described configuration diagram of the FIG. 6A in battery packs 14 and 15. The voltage of the power unit 32a is increased by serially arranging two battery packs 14, 15.
Further, as shown in FIG. 6C, it is known that a power unit 32b of an electric tool 30b has an operational time extended by arranging two battery packs 14, 15 in parallel.
Other power units for driving an electric tool are also known, for example from EP2022990 , EP2333335 , and from JP H02 89000 that defines a power unit according to the preamble of claim 1.
However, with the configuration of a conventional electric tool, even by arranging a plurality of battery packs serially or in parallel as shown in FIGs. 6B and 6C, there is a problem that the discharging performance cannot be improved as only one hydraulic pump is arranged.
Further, as shown in FIG. 6A, in case of arranging a set of plural conventional electric tools, as shown in FIG. 6A, there is a problem that the mass increases to inhibit the operability and causes an increase in the cost.
In this situation, the present invention has been developed to solve the above-described conventional problems, and an object of the invention is to provide an electric tool that is appropriately applicable to variations of various specifications by increasing the quantity of hydraulic pump to a plurality and thereby improving the discharging performance, and can improve the operability and handling by simplifying the configuration and decreasing the weight of the electric tool.
In an aspect of the invention, there is provided a power unit for driving an electric tool head to which a piston for operating a tool is attached, by pressure-transporting hydraulic oil, the power unit comprising: a first power unit; and a second power unit, wherein the first power unit includes: a first hydraulic pump for pressure-transporting the hydraulic oil; a first motor for driving the first hydraulic pump; and a first fluid passage for pressure-transporting the hydraulic oil from the first hydraulic pump to the electric tool head, and wherein the second power unit includes: a second hydraulic pump for pressure-transporting the hydraulic oil; a second motor for driving the second hydraulic pump; and a second fluid passage for pressure-transporting the hydraulic oil from the second hydraulic pump to the electric tool head; the power unit further comprising: a converging joint for converging the first fluid passage and the second fluid passage; a pressure restricting device arranged between the converging joint and the first hydraulic pump to restrict rise in pressure in the first fluid passage; and a returning device arranged between the converging joint and the second hydraulic pump to drain the hydraulic oil from the second fluid passage and thereby enable return operation of the piston, wherein the power unit pressure-transports the hydraulic oil from the converging joint to the electric tool head to drive the electric tool head; characterised in that: the first power unit includes a first battery pack for rotating the first motor, and the second power unit includes a second battery pack for rotating the second motor.
In another aspect there is provided an electric tool comprising: the power unit and the electric tool head according to the preceding aspect, wherein the power unit is arranged being separate from the electric tool head, and wherein the power unit and the electric tool head are connected by a hydraulic hose.
According to an aspect, selection from variations 1-3 with three specifications described below is possible.

Variation 1 : A using state in which only the first power unit is driven and the second power unit is not driven.
Variation 2 : A using state in which only the second power unit is driven, and the first power unit is not driven.
Variation 3 : A state in which both the first power unit and the second power unit are simultaneously driven.

As a result, depending on the thickness, the shape, the hardness, and the like, the electric tool can be used with high productivity and efficiency, by selection from the three variations, taking into account the motor output and the length of the operation time which are necessary.
Further, in a case where power is the first priority, as plural motors and hydraulic pumps are operated by selecting Variation 3 which simultaneously drives the first power unit and the second power unit, it is possible to improve the discharging performance of the hydraulic oil amount and the hydraulic pressure.
Still further, as the power unit is provided with the converging joint for converging the first fluid passage of the first power unit and the second fluid passage of the second power unit, the first fluid passage and the second fluid passage can communicate with each other. Thus, by using the pressure restricting device and the returning device in a shared state, the first fluid passage and the second fluid passage respectively function.
Accordingly, while in a conventional configuration, one pressure restricting device and one returning device were arranged individually for each motor (each hydraulic pump), it is possible according to the invention to make a pressure restricting device and a returning device shared and arranged in a quantity of one, which enables simple configuration, cost reduction, and weight reduction and thereby improves the operability and handling.
Furthermore, the first power unit is provided with the first battery pack for rotating the first motor, and the second power unit is provided with the second battery pack for rotating the second motor. Thus, matching the thickness, the shape, and the hardness of a work, it is possible to make selection from Variation 1 or Variation 2 for processing with one battery pack, and Variation 3 with two battery packs.
According to another aspect, the power unit for the electric tool is arranged being separate from the electric tool head. Thus, as weight reduction and compact size of the electric tool head can be attained, the operability and handling can be further improved.
Further, by connecting the power unit and the electric tool head by a flexible hydraulic hose, the workability of the electric tool head can be ensured.

FIG. 1 is a configuration diagram showing the electric tool head and the power unit of an electric tool according to the invention;
FIG. 2 is a cross-sectional view of the electric tool head;
FIG. 3A is a plan view of the power unit, FIG. 3B is a cross-sectional view taken along line A-A shown in FIG. 3A, and FIG. 3C is a cross-sectional view taken along line B-B shown in FIG. 3A;
FIG. 4 is a left side view of the power unit shown in FIG. 3B;
FIG. 5 is a configuration diagram of an electric component; and
FIGs. 6A to 6C are configuration diagrams schematically showing the configurations of conventional compressing tools, wherein FIG. 6A is a schematic diagram showing configuration in which an electric tool head includes one built-in motor and one built-in hydraulic pump, and one battery pack attached thereon as a power source, FIG. 6B is a schematic diagram showing configuration in which two battery packs are serially arranged, and
FIG. 6C is a schematic diagram showing configuration in which two battery packs are arranged in parallel.

An embodiment according to the present invention will be described below, referring to the drawings. Incidentally, in the respective drawings, the same symbol will be assigned to a common element or similar elements, and overlapped description of these will be omitted.
FIG. 1 is a configuration diagram showing the power unit and the electric tool head of an electric tool according to the invention.
As shown in FIG. 1, an electric tool 10 according to the invention includes an electric tool head 11 and a power unit 20. The power unit 20 is arranged separately from the electric tool head 11. The power unit 20 and the electric tool head 11 are connected by a hydraulic hose 9.

As shown in FIG. 1, the power unit 20 includes a first power unit 20a and a second power unit 20b.
The power unit 20 corresponds to the configuration enclosed by the rectangle represented by chain double-dashed line shown in FIG. 1.
As shown in FIG. 1, in the power unit 20, the first power unit 20a and the second power unit 20b are disposed in parallel, and the first fluid passage e of the first power unit 20a and the second fluid passage f of the second power unit 20b are joined into one third fluid passage g to pressure-transport hydraulic oil.
Further, the hydraulic hose 9 is arranged between the end portion of the fluid passage g from the power unit 20 and the electric tool head 11. The joints at the both ends of the hydraulic hose 9 are preferably one-touch joints.

The first power unit 20a includes a first hydraulic pump 23a for pressure-transporting the hydraulic oil, a first motor 21a for driving the first hydraulic pump 23a via a first deceleration mechanism 22a, and the first fluid passage e for pressure-transporting the hydraulic oil from the first hydraulic pump 23a to the electric tool head 11, wherein a converging joint 12 for converging the first fluid passage e and the second fluid passage f is arranged, and a pressure restricting device 26 for restricting the pressure rise in the first fluid passage e is arranged between the converging joint 12 and the first hydraulic pump 23a.
Further, a first battery pack 14 is electrically connected to the first motor 21a.

The second power unit 20b includes a second hydraulic pump 23b for pressure-transporting the hydraulic oil, a second motor 21b for driving the second hydraulic pump 23b via a second deceleration mechanism 22b, and the second fluid passage f for pressure-transporting the hydraulic oil from the second hydraulic pump 23b to the electric tool head 11, wherein the converging joint 12 for converging the first fluid passage e and the second fluid passage f is arranged, and a returning device 25 is arranged between the converging joint 12 and the second hydraulic pump 23b to enable returning operation of the piston 6.
Further, a second battery pack 15 is electrically connected to the second motor 21b.
FIG. 3A is a plan view of the power unit, FIG. 3B is a cross-sectional view taken along line A-A shown in FIG. 3A, and FIG. 3C is a cross-sectional view taken along line B-B shown in FIG. 3A. FIG. 4 is a left side view of the power unit shown in FIG. 3B.
As shown in FIG. 3A, a first body 24a and a second body 24b are arranged in parallel, and the same oil tank 29 is attached to the respective rear ends of the first body 24a and the second body 24b. Further, the converging joint 12 is disposed at the front end portions of the first body 24a and the second body 24b.
The converging joint 12 is made from a rectangular shaped material. The converging joint 12 converges the two fluid passages, namely the first fluid passage e and the second fluid passage f, into a single third fluid passage g. Further, a pipe 12a is connected to the third fluid passage g of the converging joint 12. The pipe 12a is closed at the front end and is provided with a hole for rectangular conversion of the fluid passage. The joint 12b is connected to the pipe 12a such as to cover the hole for the rectangular conversion.

As shown in FIG. 3B, the first body 24a of the first power unit 20a includes a high-pressure plunger 27, a low-pressure plunger 28 for pressure-transporting the hydraulic oil, and the pressure restricting device 26 for leaking a pressure higher than or equal to a certain high pressure to an oil tank 29 wherein the oil tank 29 is attached to the rear end portion of the first body 24a.

The first deceleration mechanism 22a is a deceleration device arranged between the first motor 21a and the first hydraulic pump 23a to decelerate the rotational speed of the first motor 21a to an appropriate rotational speed. The rotation of the first motor 21a is transmitted to the first hydraulic pump 23a via the first deceleration mechanism 22a.

As shown in FIG. 3B, the first hydraulic pump 23a is a kind of a plunger pump. By the operation of an eccentric cam 23c, the first hydraulic pump 23a moves the high-pressure plunger 27 and the low-pressure plunger 28 up and down to pressure-transports the hydraulic oil.

In the pressure restricting device 26, upon reception of a high pressure of the hydraulic oil on the upper end surface of a spool 26a, the spool 26a sinks down against the urging force of a spring, and the drain circuit opens. As a result, the high pressure oil is drained to the oil tank 29. Although the pressure restricting device 26 is disposed on the first fluid passage e, the pressure restricting device 26 also effectively functions on the high pressure oil of the second fluid passage f by the Pascal's principle.

As shown in FIG. 3C, the second body 24b of the second power unit 20b includes the high-pressure plunger 27 and the low-pressure plunger 28 for pressure-transporting the hydraulic oil, and the returning device 25 for returning the piston 6 (see FIG. 2) to the original position. The shared oil tank 29 is attached to the rear end portion of the second body 24b.

The second deceleration mechanism 22b is a deceleration device arranged between the second motor 21b and the second hydraulic pump 23b to decelerate the rotation speed of the second motor 21b down to an appropriate speed. The second deceleration mechanism 22b is configured by a planetary gear device. The rotation of the second motor 21b is transmitted to the second hydraulic pump 23b via the second deceleration mechanism 22b.

As shown in FIG. 3C, the second hydraulic pump 23b is a kind of a plunger pump. The second hydraulic pump 23b moves the high-pressure plunger 27 and the low-pressure plunger 28 up and down by the operation of the eccentric cam 23c to pressure-transport the hydraulic oil.

The returning device 25 is a device for opening the drain circuit to return the position, to which the piston 6 (see FIG. 2) has moved forward, back to the original back position. As shown in FIG. 3C, a ball 25b is usually urged by a spring, and the drain circuit is thus closed. In this state, if a returning pin 25a is pressed and the ball 25b is pressed down, the drain circuit again opens. When the returning pin 25a is pressed down by driving a later-described returning-pin pressing device 43, the piston 6 moves back by the urging force of a returning spring 4, the hydraulic oil of the cylinder 5 (see FIG. 2) is drained to the oil tank 29, and the piston 6 returns to the original back position of the oil tank 29.
As shown in FIG. 4, the power unit 20 is arranged such that the first power unit 20a is on the left side thereof and the second power unit 20b is on the right side thereof.
The first power unit 20a on the left side is configured by the first body 24a at the upper portion and the first motor 21a at the lower portion shown by chain double-dashed lines.
The second power unit 20b on the right side is configured by the second body 24b at the upper portion and the second motor 21b at the lower portion shown by chain double-dashed lines.
Further, the device shown by chain double-dashed lines at the upper portion of the second body 24b at the upper portion on the right side is the returning-pin pressing device 43. The returning-pin pressing device 43 is configured by a motor 43a, a deceleration mechanism 43b not shown, an attaching portion 43c, and an eccentric cam 43d.
The attaching portion 43c of the returning-pin pressing device 43 is fixed to the outer circumferential surface of the second body 24b by a bolt. The eccentric cam 43d is attached to the tip end portion of the returning-pin pressing device 43, and the returning pin 25a is pressed by rotation of the eccentric cam 43d.

As shown in FIG. 2, the electric tool head 11 includes the head 1 constructing the main body part, the tool head 2 rotatably connected to the head 1, the cylinder 5 integrally fixed to the head 1, the piston 6 attached to the cylinder 5, the movable die 7 connected to the piston 6, and the fixing die 8 arranged on the tool head 2.
By this arrangement of the electric tool head 11, when the hydraulic oil is supplied to the cylinder 5, the movable die 7 connected to the piston 6 moves forward, the movable die 7 moves a work inserted between the movable die 7 and the fixing die 8, and thus the work is processed.

The tool head 2 is in a U-shape in a front view. In the tool head 2, the fixing die 8 is engaged with an inner wall surface 2b forming a frame body 2a in the U-shape, wherein the fixing die 8 engages with a small hole 2c provided on the inner wall surface 2b.
The tool head 2 is connected to the tip end portion of the head 1 by a slide pin 1a and a hinge pin 1b. In a state that the tool head 2 is closed to the head 1 (closed state), the head 1 and the tool head 2 form the frame body 2a in a rectangular shape, and the movable die 7 and the fixing die 8 are disposed, facing the frame body 2a. The electric tool head 11 performs processing work in the closed state.
On the other hand, when the slide pin 1a is pulled off, the tool head 2 rotates relative to the head 1 with the hinge pin 1b as the rotation center, and the frame body 2a in the U-shape opens to form an open state in which the fixing die 8 separates from the movable die 7.
In the open state, the electric tool head 11 enables insertion of a work, replacing work of the movable die 7 and the fixing die 8, and a maintenance work.
Further, the rear end portion of the head 1 is open in a cylindrical shape, and an inner diameter screw 1c is arranged on the inner circumferential surface so that the cylinder 5 is screwed in.

The cylinder 5 is in a hollow cylindrical shape with a bottom, and an outer diameter screw 5a is formed at the tip end portion of the outer circumferential surface. The cylinder 5 is integrally fixed by screwing the outer diameter screw 5a into the inner diameter screw 1c of the head 1. A cylinder chamber 5c is formed inside the cylinder 5. At the center of the bottom portion at the rear end of the cylinder 5, a supply inlet 5b is provided to supply the hydraulic oil, and the hydraulic hose 9 is connected to the supply inlet 5b, wherein the hydraulic hose 9 can be connected to the power unit 20 through a one touch joint. Further, the piston 6 and the returning spring 4 are inserted in the cylinder chamber 5c.

The piston 6 is fitted to the inner circumferential surface of the cylinder 5 movably forward and backward. An oil chamber 6a, for which a space is ensured by a recession, is formed on the rear end surface of the piston 6; an O-ring groove 6b is provided on the outer circumferential surface; and an O-ring 3 is attached to the O-ring groove 6b. Further, the diameter of the outer circumferential surface of the piston 6 shrinks from an intermediate degree, and the returning spring 4 is attached in the space caused by the shrinkage of the diameter.
Still further, the diameter-shrunk outer circumferential surface of the piston 6 is provided with a key groove 6c in which a screw 1d for preventing rotation is loosely fit. Yet further, the front end surface of the piston 6 is provided with a small hole 6d, and the movable die 7 is attached and fitted to the small hole 6d.
FIG. 5 is a configuration diagram of an electric component according to the invention of the present application.
As shown in FIG. 5, the electric component of the power unit 20 is provided with an electric substrate 41. On the electric substrate 41, connected are a remote controller 42 for start operation, battery packs 14, 15, motors 21a, 21b configuring the power unit 20, and the returning-pin pressing device 43 for pressing the returning pin 25a to return the piston 6 to the original position, which are electrically connected by respective wires.

The electric substrate 41 is a controller. To connecting terminals provided on a print substrate of the electric substrate 41, connected and wired are wires a to c of the remote controller 42, wires h to k of the battery packs 14, 15, wires l to o of the motors 21a, 21b, and wires p, q of the returning-pin pressing device 43.

As shown in FIG. 5, the remote controller 42 is formed in a box shape, and a cable is connected to a connector 42c. An UP press button 42a and a DOWN press button 42b are arranged on the front surface of the remote controller 42. When an operator presses the UP press button 42a of the remote controller 42, the power unit 20 operates so that a hydraulic pump, not shown, supplies the hydraulic oil. When the operator presses the DOWN press button 42b, the motor 43a of the returning-pin pressing device 43 rotates and the rotational speed is decelerated through the deceleration mechanism 43b so that the eccentric cam 43d at the tip end presses the returning pin 25a of the returning device 25 (see FIG. 4). As a result, the drain circuit opens and the hydraulic oil is returned to the oil tank 29 from the cylinder 5 of the electric tool head 11.
The operation of the electric tool 10 will be described below.

The operation is in a case of attaching the battery pack 14 to the power unit 20 shown in FIG. 1.
When the operator presses the UP press button 42a of the remote controller 42 (see FIG. 5), the hydraulic oil is supplied to the electric tool head 11. That is, the first battery pack 14 rotates the first motor 21a, and the rotation of the first motor 21a drives the first hydraulic pump 23a through the first deceleration mechanism 22a. The hydraulic oil flows through the first fluid passage e, flows through the third fluid passage g where the first fluid passage e and the second fluid passage f are converged by the converging joint 12, and is pressure-transported to the electric tool head 11. Herein, the hydraulic oil also flows through the second fluid passage f.
Accordingly, if the pressure in the first fluid passage e exceeds a restriction value, the pressure restricting device 26 arranged on the first fluid passage e operates to drain high-pressure oil to the oil tank 29.
On the other hand, when the operator presses the DOWN press button 42b of the remote controller 42 (see FIG. 5), the piston 6 of the electric tool head 11 is returned to the original position. That is, as shown in FIG. 4, the returning-pin pressing device 43 operates, and the eccentric cam 43d formed at the tip end portion of the returning-pin pressing device 43 rotates by 180 degrees to press the returning pin 25a. Then, the drain circuit (see FIG. 3B) is opened. The hydraulic oil for the piston 6 is returned to the oil tank 29 by the urging force of the returning spring 4 (see FIG. 2), and the piston 6 returns to the original back position.

The operation is in a case of attaching the battery pack 15 to the power unit 20 shown in FIG. 1.
When the operator presses the UP press button 42a of the remote controller 42 (see FIG. 5), the hydraulic oil is supplied to the electric tool head 11. That is, the first battery pack 15 rotates the second motor 21b, and the rotation of the second motor 21b drives the second hydraulic pump 23b through the second deceleration mechanism 22b. The hydraulic oil flows through the second fluid passage f, flows through the third fluid passage g where the first fluid passage e and the second fluid passage f are converged by the converging joint 12, and is pressure-transported to the electric tool head 11. Herein, the hydraulic oil also flows through the first fluid passage e.
Accordingly, even though the pressure restricting device 26 is arranged on the first fluid passage e, as the pressure restricting device 26 is connected with the second fluid passage f, if the pressure in the second fluid passage f exceeds a restriction value of a high pressure, the pressure restricting device 26 operates by the Pascal's principle to drain the high pressure oil to the oil tank 29.
On the other hand, when the operator presses the DOWN press button 42b of the remote controller 42 (see FIG. 5), the piston 6 of the electric tool head 11 is returned to the original position. That is, as shown in FIG. 4, the returning-pin pressing device 43 operates, and the eccentric cam 43d formed at the tip end portion of the returning-pin pressing device 43 rotates by 180 degrees to press the returning pin 25a. Then, the drain circuit (see FIG. 3B) is opened. The hydraulic oil for the piston 6 is returned to the oil tank 29 by the urging force of the returning spring 4 (see FIG. 2), and the piston 6 returns to the original back position.

Operation in case of attaching the battery packs 14, 15 to the power unit 20 shown in FIG. 1 will be described below.
When the operator presses the UP press button 42a of the remote controller 42 (see FIG. 5), as described above, the first battery pack 14 operates the first power unit 20a, and the second battery pack 15 operates the second power unit 20b. Then, the hydraulic oil of the first hydraulic pump 23a of the first power unit 20a converges by the converging joint 12, flowing through the first fluid passage e and the third fluid passage g, and the hydraulic oil of the second hydraulic pump 23b of the second power unit 20b also converges by the converging joint 12, flowing through the second fluid passage f and the third fluid passage g. Thus, the hydraulic oil converges at the third fluid passage g to be pressure-transported to the electric tool head 11.
Then, as shown in FIG. 2, the piston 6 quickly advances against the urging force of the returning spring 4, compresses a work (for example, am electric wire and a crimping terminal) inserted between the movable die 7 and the fixing die 8, and compressing is carried out. By this arrangement, increase in the discharging performance of the hydraulic oil amount and the hydraulic pressure is improved double.
As shown in FIG. 5, subsequently, when the DOWN press button 42b of the remote controller 42 is pressed, the piston 6 of the electric tool head 11 is returned to the original position. In detail, as shown in FIG. 4, when the returning-pin pressing device 43 operates, the eccentric cam 43d formed at the tip end portion rotates by 180 degrees to press the returning pin 25a. Then, the drain circuit (see FIG. 3B) is opened. The hydraulic oil supplied to the piston 6 is returned to the oil tank 29 by the urging force of the returning spring 4 (see FIG. 2), and the piston 6 returns to the original back position. When the processed work is picked up, the process is complete.
Incidentally, it is needless to say that various modifications and changes can be made within the scope of the technical ideas of the invention.
For example, although herein the first power unit 20a and the second power unit 20b are arranged in parallel in a quantity of two for the power unit 20, the quantity in arrangement of power units is not limited to two, and can be three, four, or another multiple plural quantity.
Further, although the motor outputs of the first motor 21a and the second motor 21b are set the same, the motor outputs may be set different. For example, assuming that the output of the first motor 21a is 10W and the output of the second motor 21b is 20W, a combination is possible in which the output of the motor in Variation 1 is 100W, the output of the motor in Variation 2 is 200W, and the output of the motor in Variation 3 is 300W (100W + 200W), wherein integrating three models into one model enables an advantage of decreasing the number of models.
Further, although the pressure restricting device 26 is arranged in the first power unit 20a and the returning device 25 is arranged in the second power unit 20b, it is also possible to arrange, in reverse, the returning device 25 in the first power unit 20a and arrange the pressure restricting device 26 in the second power unit 20b.

Description of Reference Numerals

10 electric tool
11 electric tool head
12 converging joint
14 first battery pack
15 second battery pack
20 power unit
20a first power unit
20b second power unit
21a first motor
21b second motor
22a first deceleration mechanism
22b second deceleration mechanism
23a hydraulic pump
23b second hydraulic pump
23c eccentric cam
24a first body
24b second body
25 returning device
25a returning pin
26 pressure restricting device
27 high-pressure plunger
28 low-pressure plunger
29 oil tank
41 electric substrate
42 remote controller
42a UP press button
42b DOWN press button
42c connector
43 returning-pin pressing device
43a motor
43b deceleration mechanism
43c attaching portion
43d eccentric cam
e first fluid passage
f second fluid passage
g third fluid passage

Claims

A power unit (20) for driving an electric tool head (11) to which a piston for operating a tool is attached, by pressure-transporting hydraulic oil, the power unit (20) comprising:
a first power unit (20a); and

a second power unit (20b),

wherein the first power unit (20a) includes:
a first hydraulic pump (23a) for pressure-transporting the hydraulic oil;

a first motor (21a) for driving the first hydraulic pump (23a); and

a first fluid passage (e) for pressure-transporting the hydraulic oil from the first hydraulic pump (23a) to the electric tool head (11),

and wherein the second power unit (20b) includes:
a second hydraulic pump (23b) for pressure-transporting the hydraulic oil;

a second motor (21b) for driving the second hydraulic pump (23b); and

a second fluid passage (f) for pressure-transporting the hydraulic oil from the second hydraulic pump (23b) to the electric tool head (11);

the power unit (20) further comprising:
a converging joint (12) for converging the first fluid passage (e) and the second fluid passage (f);

a pressure restricting device (26) arranged between the converging joint (12) and the first hydraulic pump (23a) to restrict rise in pressure in the first fluid passage (e); and

a returning device (25) arranged between the converging joint (12) and the second hydraulic pump (23b) to drain the hydraulic oil from the second fluid passage (f) and thereby enable return operation of the piston,

wherein the power unit (20) pressure-transports the hydraulic oil from the converging joint to the electric tool head (11) to drive the electric tool head (11);

characterised in that:
the first power unit (20a) includes a first battery pack (14) for rotating the first motor (21a); and

the second power unit (20b) includes a second battery pack (15) for rotating the second motor (21b).
An electric tool (10) comprising:
the power unit (20) and the electric tool head (11) according to claim 1,

wherein the power unit (20) is arranged being separate from the electric tool head (11),

and wherein the power unit (20) and the electric tool head (11) are connected by a hydraulic hose (9).