JP3437342B2 - Spool valve mechanism of portable hydraulic processing machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is incorporated in a portable hydraulic machine for performing desired machining such as bending and cutting so that the flow of pressurized oil accompanying the operation of a pump mechanism can be controlled. The present invention relates to a spool valve mechanism.

[0002]

2. Description of the Related Art For example, in construction sites and civil engineering sites, mechanical processing such as bending and cutting of reinforcing bars and pipes and perforation of steel sheets and shaped steels is required as required. These types of machining are performed by various portable hydraulic type processing machines called punchers and the like.

A hydraulic processing machine of this type is provided with a piston, which is slidably disposed in a cylinder, and which defines the inside of the cylinder as a starting chamber and a returning chamber. Then, the oil stored in an oil tank called a reservoir is pressure-fed to the starting chamber in the cylinder as pressure oil under the operation of the pump mechanism accompanying the driving of the motor, and the pressure oil is fed under pressure. In order to perform the desired machining according to the jig by the operation of the jig accompanying the movement of the piston,
This type of hydraulic processing machine is constructed.

Here, as such a hydraulic processing machine,
For example, a configuration including a valve mechanism for controlling the flow of pressurized oil between a reservoir and a starting chamber in a cylinder is known. As a valve mechanism of this type, for example, a spool valve device disclosed in Japanese Patent Publication No. 06-075738 is provided.

The spool valve device disclosed in the above Japanese Patent Publication No. 06-075738 is arranged so as to communicate with a flow path provided with any one pump mechanism among a plurality of pump mechanisms such as three. , Can be closed under the pressure generated by the pressure feed of pressurized oil from the pump mechanism. The spool valve device is configured so that the flow of the pressurized oil between the reservoir and the starting chamber in the cylinder can be controlled by opening and closing depending on the presence or absence of the pressure.

[0006] The remaining two pump mechanisms, for example, are respectively communicated with the starting chambers in the cylinders from the reservoirs through the individual flow paths, and the oil in the reservoirs is drained under the operation of each pump mechanism. It is directly pumped as pressurized oil to the starting chamber.

[0007]

By the way, in the known spool valve device disclosed in Japanese Patent Publication No. 06-075738, the remaining pump mechanism other than the pump mechanism communicating with the spool valve device is the oil of the reservoir. Is directly sent to the starting chamber in the cylinder as pressurized oil, whereas the pump mechanism in communication with the spool valve device merely controls the opening and closing of the spool valve.

That is, since the pump mechanism communicating with the spool valve does not have the function of pumping the pressurized oil from the reservoir to the starting chamber in the cylinder, the efficiency corresponding to the number of pump mechanisms arranged cannot be secured. .

It is an object of the present invention to provide a spool valve mechanism for a portable hydraulic processing machine which maintains a high efficiency of pumping pressurized oil by a plurality of pump mechanisms.

[0010]

In order to achieve this object, according to the present invention, a valve cylinder formed as a hollow portion having a substantially cylindrical shape is used in any one of a plurality of pump mechanisms. It is in communication with the mechanism via a flow path.

In the valve cylinder, a corresponding substantially cylindrical pilot is arranged around the gap allowing only sliding, and the pilot communicates the inside of the valve cylinder with the pump mechanism. And an outflow side communicating with the flow passage between the starting chamber of the piston cylinder and the reservoir.
The pilot is provided so that the interlocking valve element can be brought into close contact with the valve seat of the flow path communicating with the starting chamber of the piston cylinder while being pressed against the biasing force of the corresponding spring member.

A space in which a substantially cylindrical escape valve corresponding to the valve cylinder is aligned with the flow path from the pump mechanism on the inflow side in the valve cylinder through a clearance through which pressurized oil can flow. Is arranged between the pilot and the pilot. The escape valve is provided so that the interlocking valve element can be brought into close contact with the valve seat of the flow path communicating with the return chamber with respect to the starting chamber of the piston cylinder, while being pressed against the biasing force of the corresponding spring member. .

A check valve is provided so as to ensure only the inflow of pressurized oil from the space in the valve cylinder into the starting chamber of the piston cylinder, and the pressure from the pump mechanism is applied via the check valve. Oil can be pumped into the piston cylinder start chamber.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the spool valve mechanism 10 of the portable hydraulic processing machine according to the present invention is connected to any one of a plurality of pump mechanisms 12 via a flow passage 14. . The plurality of pump mechanisms including the pump mechanism 12 is, for example, about three, and these pump mechanisms are respectively arranged in communication with an oil tank 16 called a reservoir serving as an oil sump.

In the figure, the spool valve mechanism 10
Only the pump mechanism 12 is illustrated by omitting other pump mechanisms that do not communicate with the above.

The spool valve mechanism 10 is provided in a portable hydraulic processing machine 18 as shown in FIG. Such a hydraulic machine 18 includes, for example, a housing 20, a casing body 22, and a motor housing 24, and is assembled as shown by bolting or the like between them via a seal packing or the like.

In this type of hydraulic processing machine 18, for example, a motor (not shown) which can be driven and controlled under the operation of a switch means (not shown) provided on the handle 24a of the motor housing 24 is a motor. It is housed in the housing. Then, as shown in FIG. 1, the motor housing
The output shaft 26 of the motor extended from 24 is
It is rotatably inserted inside 22.

The casing main body 22 is formed, for example, with a reservoir (oil tank) 16 inside, and the pump mechanism 12 for pumping the oil accumulated in the reservoir as pressurized oil in a predetermined direction. Is continuously provided in the reservoir together with the rest of the pump mechanism.

As can be seen from FIG. 1, the pump mechanism 12
Is a cam portion 28 provided on the output shaft 26 of the motor, a ram 32 that is disposed via a needle bearing 30 around the cam portion, and reciprocates according to the displacement of the cam portion, and a pump mechanism. And a delivery valve 34 that controls opening and closing of the flow path 14. The delivery valve 34 is biased in the closing direction of the flow path under the biasing force of the corresponding spring member 36, and the oil (pressurized oil) pressurized by the reciprocating motion of the ram 32 is biased by the spring member. The pump mechanism 12 is configured so that the fluid is pumped to the flow path 14 under the opening against the pressure.

Although the pump mechanism 12 is described here, it goes without saying that other pump mechanisms have the same structure.

Further, as shown in FIGS. 1 and 2, a piston cylinder is provided on the tip (lower end in the figure) side of the casing body 22.
A piston 40 is formed and has an integral piston rod 40a, and is slidably disposed in the piston cylinder. The interior of the piston cylinder 38 is divided by the piston head 40b of the piston 40 into a back activation chamber 38a and a forward return chamber 38b, for example a return spring 42 consisting of a compression coil spring is attached to the piston rod 40a in the return chamber. It is wrapped.

In such a structure, by supplying the pressurized oil to the starting chamber 38a of the piston cylinder, the piston 40 is slid in the cylinder in the starting direction, that is, in the downward direction in the drawing, and the processing is performed along with the movement of the piston. By the operation of the jig 44, desired machining according to the processing jig is performed.

As can be seen from FIG. 2, in the embodiment of the present invention, as a portable hydraulic rebar bending machine having a bending arm having a bending roller 46 at its free end as a processing jig 44, A hydraulic processing machine 18 is illustrated. In such a reinforcing bar bending machine (portable hydraulic processing machine) 18, the bending arm (processing jig) 44 is linked to the tip (lower end in the figure) of the piston rod 40a so as to be interlocked, and the starting direction, that is, Is movable in the corresponding counterclockwise direction from the initial position extending along the axis of the piston rod 40a under the movement of the piston 40 downward in the figure.

As shown in FIG. 1, a substantially cylindrical valve cylinder 48 is provided on the wall 22a between the reservoir 16 of the casing body 22 and the piston cylinder 38. Spool valve mechanism 10
Is configured. As described above, the spool valve mechanism 10 is configured such that one of the plurality of pump mechanism 12 is connected to the flow path 14
Are communicated via.

In this spool valve mechanism 10, a substantially cylindrical pilot 50 corresponding to the valve cylinder 48 is slidably arranged in the valve cylinder through a gap that allows only sliding. As a result, the inside of the valve cylinder is defined by, for example, an inflow side 48a communicating with the flow path 14 and an outflow side 48b other than the inflow side 48a. The pilot 50, under the biasing force of the spring member 52,
It is biased to the inflow side 48a.

Here, the outflow side 48b of the valve cylinder
Is, for example, the starting chamber 38a of the piston cylinder,
This flow path can be closed by the pilot 50 that is in communication with the flow path 54 between the reservoirs 16 and is pushed against the biasing force of the spring member 52. The flow path 54 communicates with the outflow side 48b of the valve cylinder via the valve seat 54a, and the valve element 56 made of a steel ball that can be brought into close contact with the valve seat is arranged between the valve seat and the pilot pressing piece 50a. Has been done.

In this structure, the pilot pressing piece 50a is moved by the movement of the pilot 50 against the biasing force of the spring member 52.
Presses the valve body (steel ball) 56, so that the valve body is brought into close contact with the valve seat 54a of the flow path and the flow path 54 is closed. Also,
When the pilot 50 is biased in the inflow side direction by the biasing force of the spring member 52, the pressing of the valve body 56 by the pilot pressing piece 50a is released, and the valve seat 54a of the flow path is opened.

A substantially cylindrical escape valve 58 corresponding to the valve cylinder 48 is provided with a clearance 60 through which pressurized oil can flow.
A space 62 that is aligned with the flow path 14 on the inflow side 48a in the valve cylinder is provided between the pilot 50 and.

The inflow side 48a of the valve cylinder
Is the return side 38b of the piston cylinder due to the flow path 64
And is configured to be able to close the flow path under the movement of the spring member 66 against the biasing force. The escape valve 58 is formed, for example, as a needle valve that integrally has a valve body 68 that can be in close contact with the valve seat 64a.

A space 62 between the pilot 50 and the escape valve 58 is defined by a pair of spacers 70 and 71 integrally provided on both opposing ends.

Further, in the spool valve mechanism 10 of the present invention, the check valve 74 is provided in line with the space 62 between the pilot and the escape valve. The check valve 74 is a space 62 in the valve cylinder, that is, the flow path 14
Is configured so as to ensure only the inflow of pressurized oil into the starting chamber 38a of the piston cylinder.

As can be seen from FIG. 1, the opposite ends of the pilot 50 and the escape valve 58 are, for example,
The terminals of the check valves 74 are respectively engaged. In such a configuration, excessive movement of the pilot 50 and escape valve 58 under the biasing force of the corresponding spring members 52, 66 is reliably prevented under the engagement of the end of the check valve 74. Therefore, even if there is a difference in spring force between the two spring members, the pilot and escape valve are not biased to either side, and are maintained at appropriate positions.

In such a hydraulic processing machine 18, the return chamber 38b of the piston cylinder and the reservoir 16
Are directly communicated with each other by the flow path 76, and the pressurized oil filled in the return chamber is returned to the reservoir in response to the reduction in the volume of the return chamber accompanying the movement of the piston 40 in the activation direction.

Further, in the hydraulic processing machine 18, normally,
Piston cylinder start chamber 38a, return chamber 38
For example, a flexible airbag (not shown) that prevents a negative pressure from being generated due to the volume variation of b is continuously provided in the reservoir 16. By providing the airbag in this way, even if the volume changes in the starting chamber 38a and the returning chamber 38b of the piston cylinder due to the movement of the piston 40, the expansion and contraction of the airbag accompanying this will cause the expansion and contraction of the airbag 16 Since the volume is also changed, the generation of negative pressure due to the movement of the piston is reliably prevented.

For example, the operation of the spool valve mechanism 10 of the present invention will be described below based on the working operation of the reinforcing bar bending machine 18 shown in FIG.

First, the reinforcing bar bending machine 18 is erected and supported,
A reinforcing bar to be processed, for example, a reinforcing bar 80 extending vertically from a reinforced concrete structure 78 is arranged along the axis of the piston rod 40a between the bending block 82 and the stopper 84 at the tip of the reinforcing bar bending machine. To do. And
In this state, the switch is operated to operate the pump mechanism 12 under the drive of the motor to suck and compress the oil in the reservoir 16 to generate pressurized oil (see FIG. 1).

The pump mechanism other than the pump mechanism 12 is also
The motors are simultaneously operated under the drive of the above-mentioned motor, and pressurized oil is generated by the same operation. Then, the pressurized oil generated by the pump mechanism other than the pump mechanism 12 passes through the corresponding flow passages and the starting chamber 38 of the piston cylinder.
It is pumped and supplied to a.

On the other hand, the pressurized oil generated by the pump mechanism 12 pushes up the delivery valve 34 and flows out into the flow path 14, and is first pressure-fed to the space 62 of the valve cylinder through this flow path. Then, under the pressure acting on the space 62,
Pilot 50 in valve cylinder, escape valve 58
Are pushed against the biasing forces of the corresponding spring members 52 and 66, respectively, by pressing the valve body 56 against the valve seat 54a by the pilot pressing piece 50a and pressing the valve body 66 against the valve seat 64a. , The flow paths 54 and 64 are closed (see FIG. 3).

Then, the pressurized oil from the pump mechanism 12 is pressure-fed from the space 62 of the valve cylinder to the starting chamber 38a of the piston cylinder via the check valve 74, and is exchanged with the pressurized oil by the pump mechanism other than the pump mechanism 12. Due to the increase in the volume of the starting chamber due to the inflow, the piston 40 moves in the distal direction, and the bending arm 44 is rotated in the corresponding direction, that is, the counterclockwise direction (see FIG. 2). Then, Fig. 4
As shown in FIG. 11, the bending bar 44 is bent in the corresponding direction with the bending block 82 as a fulcrum by the rotation of the bending arm 44.

The return chamber 38 of the piston cylinder
Pressurized oil filled in b is the piston 40
Due to the decrease in the volume of the return chamber associated with the movement of, the fluid is returned from the channel 76 to the reservoir 16 (see FIG. 1).

When the piston 40 moves to a predetermined position under the pressure feed of the pressurized oil to the starting chamber 38a of the piston cylinder, the release valve (not shown) provided in advance on the piston flange 40b or the like causes the piston to move. The excessive movement is prevented, and the bending operation of the bending bar 80 by the bending arm 44 ends.

When the switch operation is stopped and the motor is stopped, the operation of all pump mechanisms including the pump mechanism 12 is stopped, so that the pressurized oil is pumped from the reservoir 16 to the starting chamber 38a of the piston cylinder. Is blocked.
Then, under the biasing force of the return spring 42, the piston 40
Is biased toward the initial position, that is, upward in the figure (see FIG. 3).
reference).

Here, if the pumping of the pressurized oil to the valve cylinder 48 by the pump mechanism 12 is blocked, the check valve
Since 74 is closed under the action of pressure from the starting chamber 38a of the piston cylinder, the space 62
Pressurized oil inside the oil is discharged from the gap 60 around the escape valve to the opposite side isolated by the escape valve under the pressure left in the space. Then, under the outflow of the pressurized oil through the clearance 60 around the escape valve, the pressure remaining in the space 62 decreases, and the biasing force of the corresponding spring member 66 acts on the escape valve 58, When the pressure in the space becomes equal to or less than the biasing force of the spring member, the escape valve is biased toward the initial position under the biasing force of the spring member, and as shown in FIG.
The channel 64 is opened by releasing the pressing of the valve element 68 against the channel.

When the pressure in the space 62 further decreases due to the outflow of the pressurized oil through the gap 60 due to the opening of the flow path 64, the pilot 50 then operates under the biasing force of the corresponding spring member 52. It is returned to the initial position. Then, the pressing of the valve body 56 by the pressing piece 50a of the pilot is released, so that the valve seat 54
Due to the opening of the flow path 54 due to the separation of the valve element from a, the pressurized oil filled in the starting chamber 38a of the piston cylinder is
The piston 40 is returned to the initial position shown in FIG. 1 by being returned to the reservoir 16 through the flow path, and the volume of the starting chamber is reduced accordingly.

As described above, in the spool valve mechanism 10 of the portable hydraulic processing machine of the present invention, the piston cylinder of the piston cylinder is operated under the pressure of the pressurized oil from the pump mechanism 12 communicating with the spool valve mechanism. The outflow of the pressurized oil from the starting chamber 38a is controlled, and the pressurized oil from the pump mechanism is pressure-fed to the starting chamber via the check valve 74. That is, the starting chamber 38a of the piston cylinder
In the present invention, the pump mechanism is not used as a dedicated means for controlling the outflow of the pressurized oil from the pump mechanism 12, and the pump mechanism 12 pumps the pressurized oil from the reservoir 16 to the starting chamber. Since it also serves as both the pressure feeding means, the piston 4 can pump the pressurized oil with high efficiency according to the number of pump mechanisms provided in communication with the reservoir.
0, that is, it is ensured when the processing jig such as the bending arm 44 is started.

Therefore, by shortening the time required for the pressurized oil to be pumped from the reservoir 16 to the starting chamber 38a of the piston cylinder, a more rapid machining operation in the portable hydraulic machine can be sufficiently obtained.

Here, in the embodiment of the present invention, a separate steel ball is illustrated as the valve body 56 corresponding to the pilot 50, but the movement of the pilot against the biasing force of the spring member 52 may also be performed. It suffices to close the flow path 54 by means of, and the present invention is not limited to this. For example, the flow path 54 may be opened and closed by a valve body integrated with the pilot.

Further, the escape valve 58 is embodied as a needle valve having a valve body 68 integrally,
Depending on the magnitude of the pressure of the pressurized oil from the pump mechanism 12,
The escape valve is not limited to the needle valve, as long as it can open and close the corresponding channel 64, and the escape valve may be configured by other valve means.

However, if the escape valve 58 is a needle valve, since the valve body 68 is integrated, no malfunction occurs even under the flow of the pressurized oil from the gap 60 between the valve cylinder 48. The opening and closing of the flow path 64 can be easily ensured according to the pressure acting on the space 62.

Further, in this embodiment, the number of the plurality of pump mechanisms is three, including the pump mechanism 12 communicating with the spool valve mechanism 10, but the number of pump mechanisms is plural. However, the number is not limited to three and may be two or four or more.

By the way, in the embodiment of the present invention, both the pilot 50 and the escape valve 58 are slidably arranged with respect to the valve cylinder 48, and the space 62 is provided through the gap 60 around the escape valve. The pressure left inside is released to the other. However, by releasing the pressure in the space of the valve cylinder 48, it is sufficient as long as it is possible to secure the outflow of the pressurized oil from the starting chamber 38a of the piston cylinder to the reservoir 16, and thus the present invention is not limited to this.
If a gap is provided around the pilot 50 to allow pressurized oil to flow, the same operation as in the above-described embodiment can be obtained even if the escape valve is omitted from the valve cylinder.

That is, the valve cylinder 48 and the pilot 50
A space is provided between the
2, that is, if the pilot can be slid under the magnitude of the pressure generated on the inflow side communicating with the pump mechanism 12, the pump mechanism can be controlled by a means for controlling the pressurized oil without using the escape valve 58. It is possible to secure the spool valve mechanism 10 that can be used as both of the pressure feeding means. Therefore, the spool valve mechanism 10 is not limited to the presence or absence of the escape valve 58, and the valve cylinder 48 communicating with the pump mechanism 12 is not limited thereto.
It can be easily constructed by providing a check valve 74 in communication with the inflow side 48a.

In the embodiment of the present invention,
The rebar bending machine 18 using the rotatable bending arm 44 as a jig is embodied as a portable hydraulic machine, but it is a portable machine for machining under the movement of the piston accompanying the flow of pressurized oil. Since a hydraulic processing machine is sufficient, it is not limited to a reinforcing bar bending machine, and the spool valve mechanism of the present invention may be applied to other portable hydraulic processing machines such as a reinforcing bar cutter and an electric puncher. .

The above-described embodiments of the present invention are for explaining the present invention, and do not limit the present invention in any way, and those which are modified or modified within the technical scope of the present invention are also applicable. It goes without saying that all are included in this invention.

[0056]

As described above, according to the spool valve mechanism of the portable hydraulic processing machine according to the present invention, the pump mechanism communicated with the spool valve mechanism pressurizes the starting chamber of the piston cylinder to the reservoir. Depending on the number of pump mechanisms provided in communication with the reservoir, it serves both as a control means for controlling the outflow of oil and a pressure feeding means for feeding pressurized oil from the reservoir to the starting chamber. Efficient pumping of pressurized oil is ensured during processing of the work piece.

Therefore, by shortening the time for sending the pressurized oil from the reservoir to the starting chamber of the piston cylinder, it is possible to sufficiently obtain a quicker working operation in the portable hydraulic working machine.

If the escape valve is formed as a needle valve, since the valve body is integrated, a malfunction does not occur even when the pressurized oil flows through the gap between the valve cylinder and the valve cylinder. The opening and closing of the flow path can be easily ensured according to the pressure acting on the space between the escape valve and the pilot.

[Brief description of drawings]

FIG. 1 is a schematic operation diagram of a spool valve mechanism of a portable hydraulic processing machine according to the present invention in an initial state.

FIG. 2 is a schematic front view of a portable hydraulic rebar bending machine (portable hydraulic machine).

FIG. 3 is a schematic operation diagram of a spool valve mechanism of a portable hydraulic processing machine at the time of pressurization by a pump mechanism.

FIG. 4 is a schematic front view of a portable hydraulic rebar bending machine (portable hydraulic machine) during operation of a bending arm (machining jig).

[Explanation of symbols]

10 Portable hydraulic processing machine spool valve mechanism 12 Pump mechanism 14 Flow path 16 Reservoir (oil tank) 18 Portable hydraulic processing machine (portable hydraulic rebar bending machine) 38 Piston cylinder 38a Piston cylinder start chamber 40 Piston 40a Piston rod 44 Processing jig (bending arm) 48 Valve housing 50 Pilot 52 Spring member 54 Flow path 54a Flow path valve seat 56 Valve body 58 Escape valve 60 Gap 62 Space 64 Flow path 64a Flow path valve seat 66 Spring member 68 Disc 74 Check valve 76 Flow path

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) B21D 7/024 B21F 1/00 B30B 1/32 B30B 15/18 B23Q 5/26

Claims (3)

(57) [Claims] 1. A processing jig that moves a piston in a corresponding direction by supplying pressurized oil to a starting chamber of a piston cylinder by a plurality of pump mechanisms communicating with a reservoir that serves as an oil sump, and a working jig accompanying the movement of the piston. In a portable hydraulic machine that performs the desired machining according to the machining jig, it is formed as a hollow part with a substantially cylindrical shape, and flows into any one of a plurality of pump mechanisms. A valve cylinder communicating through a passage; formed in a substantially cylindrical shape corresponding to the valve cylinder, and arranged so as to surround a gap that allows only sliding, so that the inside of the valve cylinder communicates with the pump mechanism Separately regulates the inflow side and the outflow side that communicates with the flow path between the piston chamber and the reservoir, and the valve seat of this outflow side flow path. A pilot that allows close contact with the corresponding valve body under pressure against the biasing force of the spring member; a substantially cylindrical shape corresponding to the above valve cylinder, and around the gap through which pressurized oil can flow. Via the inflow side in the valve cylinder with a space aligned with the flow path from the pump mechanism between the pilot and the interlocking valve body to communicate with the return chamber for the starting chamber of the piston cylinder An escape valve that can be closely attached to the valve seat of the flow path under pressure against the biasing force of the corresponding spring member;
A check valve which is provided in alignment with a space between the pilot and the escape valve and ensures only the inflow of pressurized oil from the space into the starting chamber of the piston cylinder; and the pump through the check valve. A spool valve mechanism for a portable hydraulic processing machine, wherein pressurized oil from the mechanism can be pumped to a starting chamber of a piston cylinder. 2. The spool valve mechanism of a portable hydraulic processing machine according to claim 1, wherein the escape valve is a needle valve integrally provided with a valve body. 3. A jig for moving a piston in a corresponding direction by supplying pressurized oil to a starting chamber of a piston cylinder by a plurality of pump mechanisms communicating with a reservoir serving as an oil sump, and a machining jig accompanying the movement of the piston. In a portable hydraulic machine that performs the desired machining according to the machining jig, it is formed as a hollow part with a substantially cylindrical shape, and flows into any one of a plurality of pump mechanisms. A valve cylinder communicating through a passage; formed in a substantially cylindrical shape corresponding to the valve cylinder, and arranged so as to surround a gap through which pressurized oil can flow, so that the inside of the valve cylinder communicates with the pump mechanism. Separately regulates the inflow side and the outflow side communicating with the flow path between the piston cylinder start chamber and the reservoir, and at the valve seat of this outflow side flow path. A pilot that allows the corresponding valve element to be in close contact with the valve member by pressing it against the biasing force of the spring member; communicated with the inflow side of the valve cylinder, and the inflow of pressurized oil from that side into the starting chamber of the piston cylinder. And a check valve for ensuring only that the pressurized oil from the pump mechanism can be pumped to the starting chamber of the piston cylinder through the check valve. Valve mechanism.