JP2021006355A - Electric hydraulic tool - Google Patents

Abstract

To provide an electric hydraulic tool which can advance a piston of a single-acting hydraulic cylinder by a start switch turning-on operation and return the piston to its original position if performing a returning operation once.SOLUTION: A return valve 48 includes a spool valve piece 48d which is slidably fitted into a valve bore 48a, forms a first oil chamber 48b which is communicated with a first supply oil passage 50 in the valve bore 48a and a second oil chamber 48c which is communicated with a drain oil passage 56, opens between a hydraulic cylinder 34 and the drain oil passage 56 at the returning position, and closes between the hydraulic cylinder 34 and the drain oil passage 56 at a blocking position. A throttle is provided to increase pressure in the first oil chamber 48b more than a return passage during circulation of hydraulic oil supplied from a hydraulic pump 20 in a supply passage 52 between the hydraulic cylinder 34 and the return valve 48 of the supply oil passages 50 and 52 for supplying hydraulic oil to the hydraulic cylinder 34.SELECTED DRAWING: Figure 6

Description

The present invention relates to an electric hydraulic tool.

An electric motor, a hydraulic pump provided in a housing connected to one end of the electric motor and driven to rotate by the electric motor, and a hydraulic pump provided in the housing on the opposite side of the electric motor and pumped from the hydraulic pump. A hydraulic cylinder driven by hydraulic oil is integrally equipped with a relief valve for maintaining the hydraulic pressure in the hydraulic circuit below a certain limit and a return valve for releasing the hydraulic pressure, and the hydraulic cylinder drives a predetermined work tool. A type of electric hydraulic tool is known. For example, the electric hydraulic tool described in Patent Document 1 is that. A relatively large load is required for such an electric hydraulic tool because a cutting tool driven by the hydraulic cylinder, a crimping terminal for an electric wire, a compression tool, an iron plate drilling tool, and the like are selectively mounted. Cutting work of reinforcing bars and large-diameter electric wires, crimping work of large crimp terminals to large-diameter electric wires, compression work of tubular joints for connection to pipes, drilling work using punch tools, etc. are efficiently performed.

In the above electric hydraulic tool, when the cutting work, crimping work, compression work, or drilling work is completed, the piston of the hydraulic cylinder is returned to the original position by operating the return lever to start the next work. Met. For this reason, it is necessary to temporarily release the finger from the start switch and operate the return lever for each work, which has a drawback that labor and time are increased in the work operation.

On the other hand, in the electric hydraulic tool described in Patent Document 2, the first operation mode and the second operation mode can be selected by using the operation of rotating the operation screw, and the start switch is set in the first operation mode. By turning off the operation, the piston of the hydraulic cylinder is automatically returned to the original position. In the second operation mode, the piston of the hydraulic cylinder is advanced by operating the start switch on, and the piston of the hydraulic cylinder is operated by turning off. I try to stop the work on the spot.

Japanese Unexamined Patent Publication No. 2013-066897 Japanese Unexamined Patent Publication No. 2018-058146

However, in the electric hydraulic tool described in the patent document, in order to return the piston of the hydraulic cylinder to the original position from the end of the work in the second operation mode, the circular operating body that switches the switching valve is rotated. Since it is necessary to switch to the first operation mode, the rotation operation for the circular operating body is complicated and takes time, so that there is a drawback that the work efficiency is lowered.

The present invention has been made in the background of the above circumstances, and an object of the present invention is to automatically return the piston of the hydraulic cylinder to the original position by performing a return operation once at the end of the work. It is possible to provide an electric hydraulic tool capable of advancing the piston of the hydraulic cylinder by turning on the start switch without needing to switch the operation mode after the piston of the hydraulic cylinder returns to the original position. It is in.

The gist of the first invention for achieving such an object is (a) a single-acting type having a hydraulic pump rotationally driven by an electric motor and a piston operated by hydraulic oil pumped from the hydraulic pump. The hydraulic cylinder is provided between the hydraulic cylinder, the hydraulic pump, and the hydraulic cylinder, and from a blocking position that prevents the hydraulic oil in the hydraulic cylinder from being discharged to the drain oil passage by the return operation member. An electric hydraulic tool including a return valve that discharges the hydraulic oil inside to a drain oil passage and switches the piston of the hydraulic cylinder to a return position to return to the original position. (B) The return valve is the said. A valve bore that opens a supply oil passage that supplies hydraulic oil to the hydraulic cylinder, a return oil passage that returns hydraulic oil from the hydraulic cylinder, and a drain oil passage that discharges hydraulic oil, and a valve bore that is slidably fitted into the valve bore. A first oil chamber communicating with the supply oil passage and a second oil chamber communicating with the drain oil passage are formed in the valve bore, and at the return position, the hydraulic cylinder and the drain oil passage are opened. The blocking position includes a spool valve that closes between the hydraulic cylinder and the drain oil passage, and (c) the hydraulic pressure between the hydraulic cylinder and the return valve in the supply oil passage. A throttle is provided to increase the pressure in the first oil chamber more than in the return oil passage when the hydraulic oil supplied from the pump is circulated.

According to the electric hydraulic tool of the first invention, the return valve has a supply oil passage for supplying hydraulic oil to the hydraulic cylinder, a return oil passage for returning hydraulic oil from the hydraulic cylinder, and a drain oil passage for discharging hydraulic oil. A valve bore that opens and a first oil chamber that is slidably fitted into the valve bore and communicates with the supply oil passage and a second oil chamber that communicates with the drain oil passage are formed in the valve bore. A spool valve that opens between the hydraulic cylinder and the drain oil passage at the return position and closes between the hydraulic cylinder and the drain oil passage at the blocking position is provided, and is included in the supply oil passage. A throttle is provided between the hydraulic cylinder and the return valve to increase the pressure in the first oil chamber more than in the return oil passage when the hydraulic oil supplied from the hydraulic pump flows. Therefore, when the return operation member is not operated, cutting work, crimping work, compression work, or drilling work is performed by a tool that is operated according to the hydraulic oil supplied from the hydraulic pump according to the on / off of the electric motor. .. When the work is completed and the return operation member is once operated and the spool valve is switched from the blocking position to the return position, the inside of the hydraulic cylinder is connected to the drain oil passage, and the piston of the hydraulic cylinder is automatically returned to the original position. Be retreated. In this state, when the electric motor is turned on again, cutting work, crimping work, compression work, etc. are performed by a tool that is immediately operated according to the hydraulic oil supplied from the hydraulic pump without the need to switch the operation mode. Alternatively, drilling work is performed.

Preferably, the spool valve has a land that divides the inside of the valve bore into the first oil chamber and the second oil chamber, and the pressure in the first oil chamber is higher than that in the hydraulic cylinder. Is positioned at the blocking position by the differential pressure acting on both end faces of the land. From this, when the hydraulic oil is supplied from the hydraulic pump to the hydraulic cylinder, the spool valve is positioned at the blocking position, so that it is not necessary to switch the operation mode after the return operation by the return operation member. , You can start working immediately.

Preferably, the spool valve that is slidably fitted in the valve bore is seated directly or indirectly at the opening of the return oil passage that opens in the valve bore at the blocking position. The opening of the path is closed, and at the return position, the opening of the return oil passage that opens to the valve bore is opened, and the land is larger than the pressure receiving area of the pressure receiving surface that the spool valve receives from the return oil passage. The pressure receiving area of the pressure receiving surface received from the first oil chamber is larger. As a result, as long as the inside of the hydraulic cylinder is in a pressurized state, the land is from the pressure in the first oil chamber rather than the thrust in the valve opening direction that the spool valve receives based on the pressure in the return oil passage. Since the thrust in the valve closing direction received is large based on the above, the blocking position of the spool valve is maintained even if the electric motor stops once during the pressurization work, so even if the electric motor stops once, it will be restarted thereafter. The pressurization work can be resumed immediately by the start operation.

Preferably, the electric hydraulic tool has an oil tank in which hydraulic oil sucked by the hydraulic pump is stored, and the hydraulic cylinder when the pressure of the hydraulic oil in the hydraulic cylinder exceeds a preset relief pressure. Since it is equipped with a relief valve that discharges the hydraulic oil inside to the oil tank and suppresses the pressure rise, it is possible to prevent the internal pressure of the hydraulic cylinder from rising abnormally, and the tools driven by the hydraulic cylinder are damaged. Be prevented.

It is a front view which shows the electric hydraulic tool of one Example of this invention. It is sectional drawing which shows the main part of the electric hydraulic tool of FIG. FIG. 3 is a sectional view taken along line III-III of FIG. FIG. 3 is a sectional view taken along line IV-IV of FIG. FIG. 3 is a sectional view taken along line VV of FIG. It is a figure which shows the hydraulic circuit provided in the electric hydraulic tool of FIG. In order to explain the operation of the electric hydraulic tool of FIG. 1, the relief valve, the return valve, the second check valve, the first supply oil passage and the second supply oil passage, the return oil passage, and the drain oil passage are made in the same plane. It is an unfolded figure and is a figure which shows the state which the hydraulic oil discharged from a hydraulic pump is supplied to a hydraulic cylinder. In order to explain the operation of the electric hydraulic tool of FIG. 1, the relief valve, the return valve, the second check valve, the first supply oil passage and the second supply oil passage, the return oil passage, and the drain oil passage are made in the same plane. It is the figure which shows unfolded, and is the figure which shows the state which the return lever was operated. In order to explain the operation of the electric hydraulic tool of FIG. 1, the relief valve, the return valve, the second check valve, the first supply oil passage and the second supply oil passage, the return oil passage, and the drain oil passage are made in the same plane. It is the figure which shows unfolded, and is the figure which shows the state after the return lever is operated once.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an overall configuration of an electric hydraulic tool 10 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a main configuration of the electric hydraulic tool 10. The electric hydraulic tool 10 accommodates an electric motor 16 having a grip 14 provided with a start switch 12, a reduction gear mechanism 18 for transmitting the rotational force of the electric motor 16, a hydraulic pump 20, and a hydraulic circuit 22, and hydraulic oil. It is provided with a housing 26 to which an oil tank 24 in which the oil tank 24 is stored is attached, and a single-acting hydraulic cylinder 34 connected to the housing 26 via a universal joint 32 and a short pipe 33. The hydraulic cylinder 34 includes a piston 28 formed with a female screw into which a connecting screw for connecting a male mold of a drilling punch tool (not shown) is screwed through a female mold, and a return spring 30 for urging the piston 28 toward its original position. Is provided in the cylinder bore 34a. FIG. 2 shows a state in which the piston 28 is in the original position.

The universal joint 32, the short pipe 33, and the hydraulic cylinder 34 are detachably fixed to the housing 26 in order to use a hole punching tool. The flange portion 35 formed at the end of the short pipe 33 is detachably fastened to the housing 26 by the fastening bolt 37. Then, the above-mentioned punching tool can be replaced with another tool by using the fastening bolt 37.

The reduction gear mechanism 18 has an output gear 16a of the electric motor 16 and a large-diameter gear 18a fixed to the shaft end of the crankshaft 36 and meshing with the output gear 16a, and decelerates the rotation of the electric motor 16 to reduce the crankshaft. Communicate to 36. The crankshaft 36 is rotatably supported by the housing 26 around the rotation center line C1 via bearings 38, 40, 42.

The hydraulic pump 20 for sucking hydraulic oil from the oil tank 24 has a pump chamber 20b formed in the housing 26 so as to communicate with the oil tank 24 via a first check valve 20a (see FIG. 5) described later, and a pump. A plunger 20d provided in the chamber 20b, one end engaging with the eccentric shaft portion 36a of the crank shaft 36 and the other end being urged to one end side by a spring 20c, and a first check valve 20a from the oil tank 24. The hydraulic oil sucked into the pump chamber 20b is discharged through the second check valve 20e (see FIG. 5) described later.

FIG. 3 is a sectional view taken along line III-III of FIG. 1, which is a cross-sectional view of the housing 26 orthogonal to the rotation center line C1 and including the center line C2 of the relief valve 44 and the center line C3 of the return valve 48. FIG. 4 is a sectional view taken along line IV-IV of FIG. 3, which is a cross section of the housing 26 parallel to the rotation center line C1 and including the center line C3 of the return valve 48. FIG. 5 is a sectional view taken along line VV of FIG. 3, which is a cross section parallel to the rotation center line C1 and orthogonal to the pump chamber 20b of the hydraulic pump 20 and the center line C4 of the plunger 20d. FIG. 5 shows a cross section of the first check valve 20a and the second check valve 20e. FIG. 6 is a diagram illustrating a hydraulic circuit 22 provided in the housing 26 of the electric hydraulic tool 10.

As shown in FIGS. 3 and 4, when the pressure of the hydraulic oil in the hydraulic cylinder 34 exceeds a preset relief pressure, the hydraulic oil in the hydraulic cylinder 34 is discharged to the oil tank 24 in the housing 26. The relief valve 44 that suppresses the pressure rise in the hydraulic cylinder 34 and the blocking position are switched to the blocking position when the hydraulic oil is supplied to the hydraulic cylinder 34, but the blocking position is performed by the return operation by the return lever 46 corresponding to the return operation member. A return valve 48 for switching from to the return position is provided. The base end portion of the return lever 46 is connected to the outer end portion of the spool valve 48d described later on the first oil chamber 48b side.

As shown in FIGS. 2, 5 and 6, when the crankshaft 36 is rotationally driven by the electric motor 16 that is activated by turning on the start switch 12, the plunger 20d is reciprocated into the pump chamber 20b. The hydraulic oil sucked from the oil tank 24 through the first check valve 20a into the pump chamber 20b is supplied to the hydraulic cylinder 34 through the first supply oil passage 50 and the subsequent second supply oil passage 52 through the second check valve 20e. To. The first supply oil passage 50 and the second supply oil passage 52 constitute a supply oil passage. As shown in FIGS. 3 and 4, the second supply oil passage 52 functions as a throttle having a reduced cross-sectional area.

As shown in FIG. 6, the hydraulic oil from the hydraulic cylinder 34 is collected in the oil tank 24 via the return oil passage 54 provided with the return valve 48. Further, on the upstream side of the return oil passage 54 with respect to the return valve 48, when the pressure of the hydraulic oil in the hydraulic cylinder 34 exceeds a preset relief pressure, the hydraulic oil in the hydraulic cylinder 34 is transferred to the oil tank 24. A relief valve 44 is provided for discharging and suppressing an increase in pressure in the hydraulic cylinder 34. The second supply oil passage 52 that functions as the throttle is set to be smaller in diameter than the first supply oil passage 50 and the return oil passage 54 so as to have a diameter of about 1/6, from the hydraulic pump 20 to the hydraulic cylinder 34. In the state where the hydraulic oil is circulated, a differential pressure is generated between the inside of the first supply oil passage 50 and the inside of the return oil passage 54, and the pressure in the first supply oil passage 50 is the pressure in the return oil passage 54. Is designed to be larger than.

As shown in FIGS. 3 and 4, the return valve 48 includes a valve bore 48a and a spool valve 48d slidably fitted into the valve bore 48a. The valve bore 48a has a first supply oil passage 50 and a second supply oil passage 52 for supplying hydraulic oil to the hydraulic cylinder 34, a return oil passage 54 for returning hydraulic oil from the hydraulic cylinder 34, and hydraulic oil to the oil tank 24. The drain oil passage 56 for discharging is open. The spool valve 48d is selectively positioned at a return position that opens between the return oil passage 54 and the drain oil passage 56 and a blocking position that closes between the return oil passage 54 and the drain oil passage 56. The spool valve 48d is provided in a first oil chamber 48b communicating with the first supply oil passage 50 and the second supply oil passage 52, and a second oil chamber 48c communicating with the return oil passage 54 and the drain oil passage 56. It has a pair of lands 48e that divide the space in the valve bore 48a. A first supply oil passage 50 and a second supply oil passage 52 are opened in the first oil chamber 48b, and a return oil passage 54 and a drain oil passage 56 are opened in the second oil chamber 48c.

The return oil passage 54 is opened at an end surface of the inner wall surface on the second oil chamber 48c side in the valve bore 48a at a position concentric with the center line C3, and the steel ball 48f that closes the opening is the second spool valve 48d. 2 It is inserted between the inner end on the oil chamber 48c side and the opening of the return oil passage 54. That is, the opening of the return oil passage 54 functions as a valve seat, and the inner end portion of the spool valve valve 48d can be indirectly seated in the opening of the return oil passage 54 via the steel ball 48f. The steel ball 48f may be provided integrally with the spool valve 48d, or if the shape of the inner end portion of the spool valve 48d is, for example, spherical or tapered, the steel ball 48f may be directly inserted into the opening of the return oil passage 54. You may be seated.

The diameter of the return oil passage 54 is sufficiently smaller than the diameter of the valve bore 48a, and the cross-sectional area of the return oil passage 54 is smaller than the cross-sectional area effective for receiving the pressure of the land 48e. Therefore, the land 48e operates in the first oil chamber 48b, that is, in the hydraulic cylinder 34, rather than the pressure receiving area of the pressure receiving surface S2 of the second pressure receiving surface that the spool valve 48d substantially receives from the hydraulic oil in the return oil passage 54. The pressure receiving area of the first pressure receiving surface S1 effectively received from the oil is larger. As a result, as long as the inside of the hydraulic cylinder 34 is in a pressurized state, the pressure of the land 48e in the first oil chamber 48b is larger than the thrust in the valve opening direction received by the spool valve 48d based on the pressure in the return oil passage 54. The thrust in the valve closing direction received from the above increases.

7, 8 and 9 are views for explaining the operation of the return valve 48, in which the center line C3 of the return valve 48, the center line C2 of the relief valve 44, the first supply oil passage 50, and the second supply are supplied. It is the figure which developed the oil passage 52, the return oil passage 54, and the drain oil passage 56 in one plane. In a state where hydraulic oil is supplied from the hydraulic pump 20 to the hydraulic cylinder 34 by the electric motor 16 that is activated by turning on the start switch 12, the first oil chamber 48c is more than in the second oil chamber 48c due to the throttle effect of the second supply oil passage 52. The pressure in the oil chamber 48b becomes high. In other words, the pressure in the first oil chamber 48b is higher than that in the hydraulic cylinder 34. When the spool valve 48d is urged toward the second oil chamber 48c by the differential pressure acting on both end surfaces of the land 48e to reach the blocking position, the steel ball 48f is placed at the inner end of the spool valve 48d and the return oil passage 54. It is sandwiched between the opening of the return oil passage 54 and seated at the opening of the return oil passage 54, and the opening of the return oil passage 54 is closed. FIG. 7 shows this state.

The base end of the return lever 46 is connected to the outer end of the spool valve 48d of the return valve 48. When the start switch 12 is turned off and the electric motor 16 is stopped by the end of the work, and the tip of the return lever 46 is operated toward the housing 26, that is, the electric motor 16, the spool valve 48d is blocked. It is moved from the position to the return position. FIG. 8 shows this state. In this state, the supply of hydraulic oil from the hydraulic pump 20 is stopped and no differential pressure is generated between the inside of the first supply oil passage 50 and the inside of the return oil passage 54, so that the spool valve valve 48d is It is maintained in the return position.

As a result, once the tip of the return lever 46 is operated, the piston 28 of the hydraulic cylinder 34 is returned to its original position even if the tip of the return lever 46 is released. FIG. 9 shows this state. In this state, when the start switch 12 is turned on, the work using the hydraulic cylinder 34 can be started as it is.

As described above, according to the electric hydraulic tool 10 of the present embodiment, a single operation having a hydraulic pump 20 rotationally driven by an electric motor 16 and a piston 28 operated by hydraulic oil pumped from the hydraulic pump 20. From a blocking position provided between the hydraulic cylinder 34 of the type and the hydraulic pump 20 and the hydraulic cylinder 34 and preventing the hydraulic oil in the hydraulic cylinder 34 from being discharged to the drain oil passage 56 by the return lever 46. An electric hydraulic tool 10 including a return valve 48 that discharges hydraulic oil in the hydraulic cylinder 34 to a drain oil passage 56 and switches the piston 28 of the hydraulic cylinder 34 to a return position to return to the original position. Reference numeral 48 denotes a supply oil passage (first supply oil passage 50 and a second supply oil passage 52) for supplying hydraulic oil to the hydraulic cylinder 34, a return oil passage 54 for returning hydraulic oil from the hydraulic cylinder 34, and a drain for discharging hydraulic oil. A valve bore 48a through which the oil passage 56 opens, and a second oil chamber 48b that is slidably fitted into the valve bore 48a and communicates with the first supply oil passage 50 and the drain oil passage 56 in the valve bore 48a. A spool valve 48d that forms an oil chamber 48c, opens between the hydraulic cylinder 34 and the drain oil passage 56 at the return position, and closes between the hydraulic cylinder 34 and the drain oil passage 56 at the blocking position. From the hydraulic pump 20, the supply oil passage (second supply oil passage 52) between the hydraulic cylinder 34 and the return valve 48 in the supply oil passages (first supply oil passage 50 and the second supply oil passage 52) A throttle (that is, a second supply oil passage 52) is provided to increase the pressure in the first oil chamber 48b rather than in the return oil passage when the hydraulic oil to be supplied is circulated.

Therefore, when the return lever 46 is not operated, cutting work, crimping work, compression work, or drilling work can be performed by a tool that is operated according to the hydraulic oil supplied from the hydraulic pump 20 according to the on / off of the electric motor 16. It is done. When the work is completed and the return operation member is once operated and the spool valve 48d is switched from the blocking position to the return position, the inside of the hydraulic cylinder 34 is connected to the drain, and the piston 28 of the hydraulic cylinder 34 is automatically returned to the original position. Is retreated. In this state, when the electric motor 16 is turned on again, cutting work, crimping work, and compression work are performed by a tool that is immediately operated according to the hydraulic oil supplied from the hydraulic pump without requiring switching of the operation mode. Alternatively, drilling work is performed.

According to the electric hydraulic tool 10 of the present embodiment, the spool valve 48d of the return valve 48 has a land 48e that divides the inside of the valve bore 48a into a first oil chamber 48b and a second oil chamber 48c, and has a hydraulic cylinder 34. When the pressure in the first oil chamber 48b is higher than that in the inside, it is automatically positioned at the blocking position by the thrust generated based on the differential pressure acting on both end surfaces of the land 48e. From this, when the hydraulic oil is supplied from the hydraulic pump to the hydraulic cylinder 34, the spool valve valve 48d is automatically positioned at the blocking position. Therefore, after the return operation by the return lever 46, the operation mode is switched. You can start working immediately without the need.

According to the electric hydraulic tool 10 of the present embodiment, the spool valve element 48d slidably fitted in the valve bore 48a is directly or indirectly connected to the opening of the return oil passage 54 opening in the valve bore 48a at the blocking position. The opening of the return oil passage 54 is closed, and at the return position, the opening of the return oil passage 54 that opens to the valve bore 48a is opened, and the spool valve 48d is substantially removed from the hydraulic oil in the return oil passage 54. The pressure receiving area of the first pressure receiving surface S1 that the land 48e effectively receives from the hydraulic oil in the first oil chamber 48b, that is, the hydraulic cylinder 34 is larger than the pressure receiving area of the second pressure receiving surface S2. As a result, as long as the inside of the hydraulic cylinder 34 is in a pressurized state, the pressure of the land 48e in the first oil chamber 48b is larger than the thrust in the valve opening direction received by the spool valve 48d based on the pressure in the return oil passage 54. Since the thrust in the valve closing direction received is large based on the above, the blocking position of the spool valve 48d is maintained even if the electric motor 16 is temporarily stopped during the pressurization work, so that the electric motor 16 can be operated during the pressurization work. Even if it is stopped once, the pressurizing work can be resumed immediately by the subsequent restart operation.

According to the electric hydraulic tool 10 of the present embodiment, the relief valve 44 is provided to discharge the hydraulic oil in the hydraulic cylinder 34 to the drain when the pressure of the hydraulic oil in the hydraulic cylinder 34 exceeds a preset relief pressure. , It is avoided that the internal pressure of the hydraulic cylinder 34 rises abnormally, and damage to the tools and the like driven by the hydraulic cylinder 34 is prevented.

Although one embodiment of the present invention has been described above with reference to the drawings, the present invention also applies to other aspects.

For example, although the first supply oil passage 50 and the second supply oil passage 52 were opened in the first oil chamber 48b of the return valve 48 described above, the first supply oil passage 50 and the second supply oil passage 52 If is connected at another place, only the first supply oil passage 50 may be configured to be opened in the first oil chamber 48b of the return valve 48.

Further, in the above-described embodiment, the steel ball 48f is provided at the opening of the return oil passage 54, but if the end of the spool valve valve 48d directly opens and closes the opening of the return oil passage 54, the steel ball 48f can be formed. It may not be provided.

Although not illustrated one by one, the present invention can be carried out in various modifications and improvements based on the knowledge of those skilled in the art.

10: Electric hydraulic tool 16: Electric motor 20: Hydraulic pump 24: Oil tank 28: Piston 34: Hydraulic cylinder 44: Relief valve 46: Return lever (return operation member)
48: Return valve 48a: Valve bore 48b: First oil chamber 48c: Second oil chamber 48d: Spool valve valve 48e: Land 48f: Steel ball 50: First supply oil passage (supply oil passage)
52: Second supply oil passage (supply oil passage, throttle)
54: Return oil passage 56: Drain oil passage S1: First pressure receiving surface (pressure receiving surface)
S2: Second pressure receiving surface (pressure receiving surface)

Claims (4)

A hydraulic pump rotationally driven by an electric motor, a single-acting hydraulic cylinder having a piston operated by hydraulic oil pumped from the hydraulic pump, and a return provided between the hydraulic pump and the hydraulic cylinder. The operating member discharges the hydraulic oil in the hydraulic cylinder to the drain oil passage from a blocking position that prevents the hydraulic oil in the hydraulic cylinder from being discharged to the drain oil passage, and causes the piston of the hydraulic cylinder to be discharged. An electric hydraulic tool equipped with a return valve that can be switched back to the original position.
The return valve slides into a valve bore in which a supply oil passage for supplying hydraulic oil to the hydraulic cylinder, a return oil passage for returning hydraulic oil from the hydraulic cylinder, and a drain oil passage for discharging hydraulic oil are opened, and a valve bore. A first oil chamber that is movably fitted and communicates with the supply oil passage and a second oil chamber that communicates with the drain oil passage are formed in the valve bore, and at the return position, the hydraulic cylinder and the drain oil are formed. A spool valve that opens between the passage and closes between the hydraulic cylinder and the drain oil passage at the blocking position is provided.
Between the hydraulic cylinder and the return valve in the supply oil passage, there is a throttle that increases the pressure in the first oil chamber more than in the return oil passage when the hydraulic oil supplied from the hydraulic pump flows. An electric hydraulic tool that is characterized by being provided. The spool valve has a land that divides the inside of the valve bore into the first oil chamber and the second oil chamber, and when the pressure in the first oil chamber is higher than that in the hydraulic cylinder, the land. The electric hydraulic tool according to claim 1, wherein the electric hydraulic tool is positioned at the blocking position by a differential pressure acting on both end surfaces of the above. The spool valve, which is slidably fitted in the valve bore, sits directly or indirectly at the opening of the return oil passage that opens in the valve bore at the blocking position to open the return oil passage. When closed and at the return position, the opening of the return oil passage that opens to the valve bore is opened.
The electric flood control according to claim 2, wherein the pressure receiving area of the pressure receiving surface that the land receives from the first oil chamber is larger than the pressure receiving area of the pressure receiving surface that the spool valve receives from the return oil passage. tool. An oil tank in which the hydraulic oil sucked by the hydraulic pump is stored, and
It is characterized by including a relief valve that discharges the hydraulic oil in the hydraulic cylinder to the oil tank to suppress the pressure increase when the pressure of the hydraulic oil in the hydraulic cylinder exceeds a preset relief pressure. The electric hydraulic tool according to any one of claims 1 to 3.

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