JPH09309079A - Pump plunger mechanism for hydraulic tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate machining of a tool body, to reduce the number of processes, and to reduce a cost. SOLUTION: A pump plunger mechanism 2 comprises a small plunger 24 coupled directly to a pump plunger 29; and a large diameter plunger 25 slidably arranged at the outer periphery of the small plunger 24 and forced into an energized state through the force of a plunger spring 31. The small and large plungers are inserted in a plunger chamber 23 in two stages of the small and large chambers between which a hydraulic circuit is located. After an output piston 8 is rapidly fed by working oil sucked in large chamber 23a by the large plunger 25, in such a state that sucked working oil by the large plunger 25 is stored in a storage state in the large chamber, the large plunger 25 is stopped. An output piston 8 brought into a load state by working oil sucked in the small chamber 23b by the large plunger 24 is pressed for movement and by effecting a work, a conventional low pressure regulation valve is eliminated and further incurring of an energy loss is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic tool used for cutting wires or connecting them by crimping in overhead wire construction, and more particularly to a pump plunger mechanism for a hydraulic tool having a rapid feed function for an output piston equipped with a movable die. Regarding

[0002]

2. Description of the Related Art A hydraulic tool used for cutting an electric wire or crimping and connecting an electric wire using a terminal or a sleeve moves a movable die attached to an output piston provided at its tip end by hydraulic pressure generated by a pump action. Although the cutting and crimping work is performed with the fixed die attached to the head part, in order to improve workability and reduce labor, there is no need to close the wire etc. between both dies. It has come to be used that the load time is kept to a minimum and a rapid feed mechanism for the output piston is used that allows high pressure oil to be pressed into the cylinder chamber that accommodates the output piston with a light force.

As hydraulic tools equipped with such a rapid-feed mechanism for pistons, there are, for example, those shown in FIGS. 7 and 8. In this manual hydraulic tool B, a tool body 51 is formed with a two-stage plunger chamber 52 consisting of a large-diameter chamber 52a and a small-diameter chamber 52b, and the plunger chamber 52 has concentric two-stage large and small diameter portions. The plunger 53 is fitted and inserted, and the pumping action of rocking the attached pressure handle 54 to reciprocate the plunger 53 sucks the working oil from the attached oil tank 55 to remove the tool body 51. The output piston 57, which is supplied to the cylinder chamber 56 formed at the front end portion and is accommodated in the cylinder chamber 56, is fast-forwarded by a low pressure when there is no load, and can be moved forward by a high pressure after the load. .

In other words, the movement of the plunger 53 in the pulling-out direction causes the large-diameter plunger portion 53a to move as shown in FIG.
The hydraulic oil is sucked into the large-diameter chamber 52a of the plunger chamber 52 via the low-pressure suction valve 58 shown in FIG. 1, and the small-diameter plunger portion 53b sucks the hydraulic oil into the small-diameter chamber 52b via the high-pressure suction valve 59. The large-diameter plunger portion 53a and the small-diameter plunger portion 53b force the suction hydraulic oil from the low-pressure discharge valve 60 and the high-pressure discharge valve 61 to the cylinder chamber 56 by the movement in the pushing direction, and the output piston 57 is fast-forwarded.

Then, the movable die (not shown) attached to the tip end of the output piston 57 comes into contact with the object to be pressure-bonded, etc. to show a reaction force, thereby causing a load on the output piston 57,
When the hydraulic fluid in the cylinder chamber 56 is continuously pressurized and reaches a predetermined hydraulic pressure, the hydraulic fluid suctioned by the large-diameter plunger portion 53a is not supplied into the cylinder chamber 56 but passes through the low pressure regulating valve 62. Then, only the suction working oil by the small diameter plunger portion 53b is pumped to the cylinder chamber 56 to increase the oil pressure, and overcome the reaction force of the object to be pressure-bonded and output. The piston 57 is pushed and moved forward to perform work such as crimping. Incidentally, 63 is a return valve for returning the hydraulic oil in the cylinder chamber 56 to the oil tank 55 after the work is completed, and 64 is a high pressure regulating valve for regulating a high pressure degree equal to or higher than a predetermined pressure.

[0006]

However, a hydraulic tool having such a hydraulic circuit has a large number of small valve mechanisms in the tool body, and in manufacturing a hydraulic tool including these valve mechanisms, particularly a tool body. However, there has been a problem that many fine and complicated processing steps are required and high processing cost is required. On the other hand, during the fast-forward operation of the output piston of the hydraulic tool, there is an energy loss that the large-diameter plunger section continues the circulation operation of the low-pressure hydraulic oil even after the fast-forward operation is completed and the pressure is switched to high pressure. Not only the oil pressure increase but also the low pressure hydraulic oil is returned to the oil tank against the low pressure control valve, which increases the resistance of the pumping operation.For example, in the case of a manual hydraulic tool, the pressure handle is heavy. There was a problem that the operation labor increased.

Therefore, according to the present invention, it is possible to easily process the tool body at the time of manufacturing the tool and the processing man-hour is reduced. Therefore, the processing cost is reduced, and at the time of operation, the low pressure hydraulic oil of the hydraulic circuit is transferred to the oil tank. An object of the present invention is to provide a hydraulic tool that does not need to be returned and reduces the resistance of pumping operation.

[0008]

To achieve the above object, the present invention provides an oil tank at the base end of a tool body having a hydraulic circuit therein, and a cylinder chamber at the front end of the tool body. A hydraulic tool equipped with a pump plunger mechanism that collects the output piston biased to the base end side by the piston return spring, sucks the working oil of the oil tank by the reciprocating motion of the pump plunger, and pumps it to the cylinder chamber. In the above, the pump plunger mechanism includes a small diameter plunger and a large diameter plunger, and the tool body has a small diameter chamber, a low pressure suction valve, and a low pressure discharge valve interposed in a high pressure oil passage between the high pressure suction valve and the high pressure discharge valve of the hydraulic circuit. A small-diameter plunger and a large-diameter plunger are fitted in the two-stage plunger chambers, each of which has a large-diameter chamber interposed in a low-pressure oil passage between them. After fast-forwarding the output piston by pressure feed of hydraulic oil by a large-diameter plunger, the large-diameter plunger is stopped while the hydraulic oil is stored in the large-diameter chamber, and the high-pressure hydraulic oil from the small-diameter chamber is made by the small-diameter plunger. A pump plunger mechanism for a hydraulic tool, characterized in that the output piston is pushed and moved forward by pressure feeding to a cylinder chamber.

The pump plunger mechanism includes the small-diameter plunger directly connected to the pump plunger and the large-diameter plunger slidably provided around the small-diameter plunger, and the small-diameter plunger has a tip portion in the small-diameter chamber. The large-diameter plunger is inserted into the large-diameter chamber while being biased inward by a plunger spring, and the small-diameter plunger locks the large-diameter plunger. The large diameter plunger can be moved against the plunger spring when the small diameter plunger is moved outward in the pulling direction, and the plunger spring has a spring force larger than that of the piston return spring. A pump plunger mechanism for a hydraulic tool is provided.

Furthermore, the small diameter chamber of the plunger chamber provides a pump plunger mechanism formed in a fitting body that is detachably screwed into the side wall of the tool body.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the manual type, the pressurizing handle is oscillated, and in the electric type, the rotational drive of the motor is converted into a linear motion by a cam crank mechanism or the like to linearly reciprocate the pump plunger. By performing the operation, the large diameter plunger and the small diameter plunger reciprocate respectively, the large diameter plunger sucks the working oil from the oil tank and pumps it into the cylinder chamber via the large diameter chamber, and the small diameter plunger also moves to the oil tank. More hydraulic oil is suctioned and pressure-fed to the cylinder chamber via the small diameter chamber, and the relatively large amount of hydraulic oil rapidly feeds the output piston in the unloaded state. After the output piston is loaded due to the close contact between the die and the object to be clamped to raise the pressure of the hydraulic oil in the cylinder chamber, the operation of the large-diameter plunger is stopped to discharge the low pressure oil in the low pressure oil passage between the cylinder chamber and the cylinder. The valve closes, and thereafter only the small diameter plunger reciprocates. That is, the small-diameter plunger pressurizes the output piston to move it forward by pressing the output piston through the small-diameter chamber by a continuous reciprocating motion regardless of the load / no-load of the output piston. Perform hydraulic work, etc.

In a small-diameter plunger directly connected to the pump plunger, which is provided with a pump plunger mechanism in which a large-diameter plunger is slidably provided around the small-diameter plunger, when the small-diameter plunger moves in the pull-out direction in the small-diameter chamber,
The large-diameter plunger in the large-diameter chamber also moves integrally by the engagement of the engagement piece of the small-diameter plunger. That is, as the small-diameter plunger moves in the pulling-out direction, hydraulic oil is sucked from the oil tank into the small-diameter chamber of the plunger chamber through the high-pressure suction valve, and also into the large-diameter chamber of the plunger chamber through the low-pressure suction valve from the oil tank. Oil is sucked in.

Next, when the pump plunger moves in the pushing direction, the large diameter plunger moves together with the small diameter plunger in the pushing direction by the urging force of the plunger spring. By pushing the small diameter plunger, the hydraulic oil in the small diameter chamber is supplied to the cylinder chamber via the high pressure discharge valve, and the hydraulic oil in the large diameter chamber is supplied to the cylinder chamber via the low pressure discharge valve by the large diameter plunger. That is, since the piston return spring of the output piston has a smaller spring force than the plunger spring, the large-diameter plunger and the small-diameter plunger move as a unit in the low-pressure hydraulic fluid state, unlike the conventional two-stage plunger. , The low-pressure hydraulic oil is pressure-fed to the cylinder chamber, and the unloaded output piston is fast-forwarded against the urging force of the return spring. The output piston fast-forwarded by the reciprocating motions of the plurality of pump plungers is brought into a loaded state when the attached movable die comes in close contact with the sandwiched object such as the object to be pressure-bonded.

Further, the hydraulic pressure in the cylinder chamber increases rapidly due to the subsequent reciprocating motion of the pump plunger, but the small diameter plunger continuously supplies the hydraulic oil sucked into the small diameter chamber to the cylinder chamber via the high pressure suction valve. The hydraulic pressure in the cylinder chamber can be increased. However, unlike the conventional case, there is no low-pressure regulating valve between the low-pressure oil passage for the large-diameter plunger and the oil tank, and the increase in the valve opening resistance of the low-pressure discharge valve due to the pressure increase of the hydraulic oil in the cylinder chamber The hydraulic oil sucked by the large-diameter plunger is stored in the large-diameter chamber as it is, and the large-diameter plunger is stopped at the substantially bottom dead center position of the plunger spring. After that, only the small-diameter plunger will continuously reciprocate. That is, the small-diameter plunger further presses the output piston in the loaded state by the high-pressure hydraulic oil to move the output piston forward, thereby performing work such as crimping with a die.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A piston plunger mechanism for a hydraulic tool according to the present invention will be described below with reference to the drawings according to the embodiments. 1 is a side sectional view of an essential part of an electric hydraulic crimping tool according to the present invention, and FIG. 2 is a sectional view taken along line II-II of FIG.
3 is a sectional view taken along the line III-III in FIG. 1 when the pump plunger is at the top dead center.
6 is a sectional view taken along the line III-III in FIG. 1 when the pump plunger is at the bottom dead center, and FIG. 5 is a sectional view taken along the line VV in FIG. FIG. 2 is a hydraulic circuit diagram of the electric hydraulic crimping tool of FIG. 1.

1 and 2, an electric hydraulic crimping tool A has an oil tank 4 attached to the base end of a tool body 1 having a pump plunger mechanism 2 and a hydraulic circuit 3. A motor 7 is provided at the bottom through a speed reducer 6.
Is provided with a power unit 5 for transmitting the rotation of the tool body 1, and a cylinder chamber 9 for accommodating the output piston 8 is formed in the front end portion of the tool body 1 as a cylinder portion 1a, and a movable die 10 is attached to the output piston 8. A fixed die 12 is arranged in front of the cylinder via a cylinder head 11 attached to the outer periphery of the cylinder portion 1a.

That is, the cylinder portion 1a at the front end portion of the tool body 1 is provided with a cylinder chamber 9 which opens forward (to the left in the drawing), and the output piston 8 is accommodated in the cylinder chamber 9 and the piston return spring 13 is provided. In the state of being urged to the rear side, that is, the base end side. A cylinder head 11 is screwed onto the outer periphery of the cylinder portion 1a, and a tool head 14 is attached to the cylinder head 11 by a slide pin 15 so that one side can be opened and closed.
A fixed die 12 is detachably attached to the movable die 1 so as to face the movable die 10 attached to the tip of the output piston 8.
By reciprocating 0, the crimping work of an electric wire or the like can be performed with the fixed die 12.

In the hydraulic circuit 3 of the tool body 1, a high pressure suction valve 16 and a low pressure suction valve 17 which are check valves are provided at the rear end portion of the tool body 1, and an oil strainer 18 is provided for each of them.
The hydraulic oil can be sucked from the oil tank 4 via the, and a high pressure discharge valve 19 and a low pressure discharge valve 20 by check valves are provided at the front end portion on the cylinder chamber 9 side.
A high pressure oil passage 21 is provided between the high pressure intake valve 16 and the high pressure discharge valve 16.
And a low pressure oil passage 22 is formed between the low pressure suction valve 17 and the low pressure discharge valve 20. The low-pressure oil passage 22 has a large-diameter chamber 2 of a plunger chamber 23 of a pump plunger mechanism 2 described later.
3a is interposed and a small diameter chamber 23b of the plunger chamber 23 is also interposed in the high pressure oil passage 21.

In the pump plunger mechanism 2, FIG.
Also, as shown in FIG. 4, the large-diameter chamber 23a and the small-diameter chamber 23, which open downward, are formed at approximately the center of the tool body 1.
a two-stage plunger chamber 23 consisting of b and
A small-diameter plunger 24 and a large-diameter plunger 25, which will be described later, can be fitted into the plunger chamber 23. The low pressure oil passage 22 penetrating in the front-rear direction is opened in the side wall portion close to the bottom of the large diameter chamber 23a so that the low pressure oil passage 22 between the oil tank 4 and the cylinder chamber 9 can be communicated. The small diameter chamber 23b is formed in a so-called cassette type fitting body 26, and the fitting body 26 is detachably attached to the side portion of the tool body 1 in a threaded state, and the small diameter chamber 23b is separately formed as described above. By forming the fitting body 26 in advance, the machining of the tool body 1 is simplified and the manufacturing process is remarkably shortened. Further, a diametrical through hole 27 passing through the internal small diameter chamber 23b is formed in a side portion of the fitting body 26, and a groove 28 is engraved on the outer periphery thereof. In the screwed state to the tool body 1,
A high-pressure oil passage between the oil tank 4 and the cylinder chamber 9 can communicate with each other.

Further, the pump plunger mechanism 2 is provided with a pump plunger 29 that reciprocates, and the small diameter plunger 24 is fixed to the pump plunger 29 by screwing, and reciprocates integrally with the pump plunger 29. It is supposed to move. The small diameter plunger and the pump plunger may be integrally formed. The large-diameter plunger 25 is in the shape of a piston, has a through hole formed in the shaft core, and is slidably fitted to the outer periphery of the small-diameter plunger 24.
The small diameter plunger 24 and the small diameter plunger 24 are fitted into the plunger chamber 23 in this combined state.

Further, the large-diameter plunger 25, in this fitted state, has a concave portion formed on the opening side of the plunger chamber 23, and the stopper 3 attached to the opening portion of the plunger chamber 23.
0 (the small-diameter plunger is in a penetrating state), the plunger spring 31 is accommodated, and the large-diameter plunger 25 is urged to the inner side (upper side in the drawing) of the large-diameter chamber 23a. The plunger spring 31 is smaller than the spring force of a high pressure regulating valve 38, which will be described later, which regulates the hydraulic pressure in the cylinder chamber 9, but has a larger spring force than the piston return spring 13 of the output piston 8. A collar-shaped locking piece 32 is provided around the middle portion of the small-diameter plunger 24, and when the small-diameter plunger 24 is pulled down, that is, when the small-diameter plunger 24 is moved in the pull-out direction, the small-diameter plunger 2
4, the large-diameter plunger 25 is forcibly pulled down.

As shown in FIG. 5, the return valve 33 can open and close the ball valve 36 urged by the spring 35 by the push pin 34 which is pressed from the outside. By this valve opening operation, the oil tank 4 is opened. The pressure hydraulic oil in the cylinder chamber 9 can be directly returned to the oil tank 4 via the return oil passage 37 that communicates with the cylinder chamber 9. Also, as shown in FIG.
In parallel with the return valve 33, a cassette type high pressure regulating valve 38
When the pressure hydraulic oil in the cylinder chamber 9 and the high pressure oil passage 21 reaches a high pressure higher than the regulation, the high pressure regulating valve 38 is opened to release the pressure hydraulic oil via the high pressure return oil passage 39. It can be returned to the oil tank 4.

The power unit 5 arranged in the lower part of the tool body 1 comprises a motor 7, a speed reducer 6 for reducing the rotation of the motor 7, and an output rotary shaft 40 from the speed reducer 6, as shown in FIGS. As shown in 4, the output rotary shaft 4
0 forms the tip end on the eccentric shaft 40a, and
An outer ring 42 is provided on 0a via a needle bearing 41. A ring portion 29a of a pump plunger 29 formed in a cam plunger type is externally fitted to the outer ring 42. This pump plunger 29
Is a part of the pump plunger mechanism 2 incorporated in the tool body 1, and has an elliptical ring portion 29.
a and the plunger portion 29 fixed to the ring portion 29a
When the eccentric shaft portion 40a of the output rotary shaft 40 is rotated by the drive of the motor 7, the ring portion 29a and the plunger portion 29b are linearly reciprocated in the vertical direction.

In the electric hydraulic crimping tool A according to the pump plunger mechanism of the present invention constructed as described above,
As shown in the hydraulic circuit diagram of FIG. 6, the operation of converting the rotational drive of the output rotary shaft 39 by the motor 7 into the linear reciprocating motion of the pump plunger 29 by the cam crank mechanism or the like, and the small diameter directly connected to the pump plunger 29 is performed. Plunger 2
Move 4 straight back and forth. When the pump plunger 29 is at the top dead center, that is, when the small diameter plunger 24 is pushed upward as shown in FIG. 3, the small diameter chamber 23b is substantially closed by the small diameter plunger 24, and The large-diameter plunger 25 is in a state of substantially blocking the large-diameter chamber 23a by the urging force of the plunger spring 31, and when the pump plunger 29 is pulled down to the bottom dead center of the plunger spring 31 as shown in FIG. The hydraulic oil is sucked into the small diameter chamber 23b from the oil tank 4 via the high pressure suction valve 16 by the small diameter plunger 24, and at the same time, the large diameter plunger 25 of the large diameter chamber 23a is locked by the locking piece 32 of the small diameter plunger 24. As a result, the plunger spring 31 is compressed and pulled down, and the large-diameter chamber 23a is connected to the low-pressure intake valve 1 from the oil tank 4.
The hydraulic oil is sucked through 7.

Then, the pump plunger 29 is pushed up to the top dead center of the plunger spring 31, whereby the small diameter plunger 24 discharges the hydraulic oil in the small diameter chamber 23b into the high pressure discharge valve 19.
The large-diameter plunger 25, which is pressure-fed to the cylinder chamber 9 via the plunger spring 31 and operates integrally with the small-diameter plunger 24 by the urging force of the plunger spring 31, presses the hydraulic oil in the large-diameter chamber 23a, The pressure is fed to the cylinder chamber 9.
Then, the output piston 8 in the cylinder chamber 9 is fast-forwarded against the urging force of the piston return spring 13 by the relatively large amount of low-pressure hydraulic oil supplied by the small-diameter plunger 24 and the large-diameter plunger 25. Due to the reciprocating movements of the plurality of pump plungers 29, the output piston 8 receives a reaction force at a stage in which the movable die 10 attached to the fast-forwarded output piston 8 comes into close contact with the object to be crimped at an early stage, and becomes a loaded state.

Further, when the hydraulic pressure of the hydraulic oil in the cylinder chamber 9 rises to a predetermined pressure due to the reciprocating movement of the pump plunger 29, the low pressure discharge valve is operated at the hydraulic pressure of the low pressure hydraulic oil by the urging force of the plunger spring 31. 20 does not open, and the hydraulic oil sucked by the large-diameter plunger 25 is stored in the large-diameter chamber 23a as it is.
Is stopped at the position of the bottom dead center of the plunger spring 31. After that, only the small-diameter plunger 24 reciprocates, and the working oil in the cylinder chamber 9 is transferred to the small-diameter plunger 24.
The operating oil supplied from the small diameter chamber further increases the pressure, further presses the output piston 8 in the loaded state and moves it forward, and the movable die 10 moves forward together with the fixed die 12 facing the object to be pressure-bonded. Perform crimping work.

When the pressure applied to the output piston 8 exceeds a predetermined pressure, the high pressure regulating valve 38 is opened to return a part of the high pressure hydraulic oil to the oil tank 4 via the high pressure return oil passage 39, and the inside of the tool Relieve pressure.

When the pressing operation is completed and the push pin 34 of the return valve 33 is pushed, the working oil in the cylinder chamber 9 is returned to the oil tank 4 as it is through the return oil passage 37 opening in the cylinder chamber 9. The high pressure oil remaining in the plunger chamber 23 and the hydraulic circuit 3 is also returned to the oil tank 4 via the cylinder chamber 9, and the output piston 8 of the cylinder chamber 9 is returned to its original position by the urging force of the piston return spring 13. Return.

Thus, after the output piston 8 is fast-forwarded,
The low-pressure hydraulic oil is not returned to the oil tank 4,
Since the operation of the large-diameter plunger 25 can be stopped in the state of being stored in a, it is not necessary to provide a low pressure regulating valve as in the conventional case, and the hydraulic oil returning to the oil tank via the low pressure regulating valve is eliminated. As a result, operating resistance is no longer increased.

In the above embodiments, the pump plunger mechanism of the present invention has been described using the electric hydraulic crimping tool, but it is naturally applicable to a manual hydraulic tool with the same configuration.

[0031]

As described above, according to the present invention, it is not necessary to return the low pressure oil sucked by the large diameter plunger to the oil tank in a circulating manner as in the prior art, and the low pressure regulating valve required in the prior art is required. Therefore, it is possible to provide a hydraulic tool in which a fine and complicated machining process related to the low pressure control valve is reduced, manufacturing is facilitated, and machining cost is also reduced. Also, with this hydraulic tool, it is no longer necessary to return the low-pressure hydraulic oil to the oil tank via the low-pressure regulating valve by means of a large-diameter plunger, which reduces the operational energy burden, especially in the case of the manual type. The pressure handle becomes heavy and the operation does not become dull.

Further, since a part of the plunger chamber is formed as a cassette type fitting body, the machining at the time of manufacturing the tool is further facilitated, and even if it is damaged during use, it can be replaced. Is obtained.

[Brief description of drawings]

FIG. 1 is a side sectional view of an essential part of an electric hydraulic crimping tool according to the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG. 1 when the pump plunger is at the top dead center.

FIG. 4 is a cross-sectional view taken along the line III-III in FIG. 1 when the pump plunger is at the bottom dead center.

5 is a sectional view taken along line VV of FIG.

FIG. 6 is a hydraulic circuit diagram of the electric hydraulic crimping tool of FIG. 1.

FIG. 7 is a side sectional view of a main part of a conventional manual hydraulic tool.

8 is a sectional view taken along the line VIII-VIII in FIG.

[Explanation of symbols]

 A Electric hydraulic crimping tool 1 Tool body 2 Pump plunger mechanism 3 Hydraulic circuit 4 Oil tank 5 Power unit 7 Motor 8 Output piston 9 Cylinder chamber 10 Movable die 11 Cylinder head 12 Fixed die 13 Piston return spring 14 Tool head 16 High pressure suction valve 17 Low pressure suction valve 19 High pressure discharge valve 20 Low pressure discharge valve 21 High pressure oil passage 22 Low pressure oil passage 23 Plunger chamber 23a Large diameter chamber 23b Small diameter chamber 24 Small diameter plunger 25 Large diameter plunger 26 Fitting body 29 Pump plunger 29a Ring portion 29b Plunger portion 31 Plunger spring 32 Locking piece 33 Return valve 37 Return oil passage 38 High pressure regulating valve 39 High pressure return oil passage 40 Output rotation shaft 40a Eccentric shaft portion

Claims (3)

[Claims] An oil tank is attached to a base end portion of a tool body in which a hydraulic circuit is provided, a cylinder chamber is formed in a front end portion of the tool body, and is biased toward the base end side by a piston return spring. In a hydraulic tool equipped with a pump plunger mechanism that collects the output piston and sucks the hydraulic oil in the oil tank by the reciprocating motion of the pump plunger and pressure-feeds it to the cylinder chamber, the pump plunger mechanism includes a small diameter plunger and a large diameter plunger. The tool body is provided with a two-stage plunger chamber consisting of a small diameter chamber interposed in the high pressure oil passage of the hydraulic circuit and a large diameter chamber interposed in the low pressure oil passage to provide the small diameter plunger and the large diameter plunger. After inserting each, fast feed the output piston by pressure feed of hydraulic oil by the large diameter plunger and the small diameter plunger, and then stop the large diameter plunger. The pump plunger mechanism in a hydraulic tool, characterized in that to move forward by pushing the output piston by the pumping to the cylinder chamber of the high pressure hydraulic fluid from the small chamber by the small-diameter plunger with. 2. The pump plunger mechanism includes the small-diameter plunger directly connected to the pump plunger and the large-diameter plunger slidably provided around the small-diameter plunger, and the small-diameter plunger has a tip portion in the plunger chamber. The large-diameter plunger is fitted into the small-diameter chamber, and the large-diameter plunger is inserted into the large-diameter chamber while being biased in the pushing direction by a plunger spring, and the small-diameter plunger has a locking piece for locking the large-diameter plunger. The large-diameter plunger can be moved around the small-diameter plunger against the plunger spring when the small-diameter plunger moves in the pulling-out direction, and the plunger spring has a larger spring force than the piston return spring of the output piston. The pump plunger mechanism in the hydraulic tool according to claim 1, wherein: 3. The pump plunger for a hydraulic tool according to claim 1, wherein the small diameter chamber of the plunger chamber is formed as a fitting body which is detachably screwed into a side wall of the tool body. mechanism.