JP2591498Y2 - Pressure fluid driven pump - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure fluid driven pump, and more particularly to a pressure fluid driven pump capable of reducing discharge pressure pulsation and increasing the discharge amount.

[0002]

2. Description of the Related Art In general, the operation of a pressure fluid type pump is automatically stopped when the pressure in a discharge passage reaches a predetermined value, and can be automatically restarted when the pressure in the discharge passage falls below a predetermined value. It is used for the preload type overload safety device of machinery. This preload-type overload safety device is described by taking, for example, an overload safety device for a press shown in FIG.
A cylinder called a booster cylinder 103 is interposed between the pressurizing mechanism (drive unit) 101 and the slide (working unit) 102 so that the pressurizing mechanism 101 and the slide 102 can be relatively displaced within a certain range. The booster cylinder 103 is filled with a pressure fluid having a constant pressure (preload), for example, pressure oil, by the pressure 104, so that the pressure can be transmitted from the pressurizing mechanism 101 to the slide 102. By discharging the fluid through the relief valve 105, the distance between the pressurizing mechanism 101 and the slide 102 is shortened to eliminate the overload condition.

A pump for supplying a pressure fluid to the booster cylinder 103 is called a booster pump 105. As the booster pump 105, a pump driven by a pressure fluid is frequently used. As this type of pump, as shown in FIG.
One single-acting cylinder 202 driven by a pressure fluid in the body 201, a directional control valve 203 for controlling the supply and discharge of the pressure fluid to and from the cylinder 202, and an external pressure fluid supply passage connected to the directional control valve Inlet flow path 204 and directional control valve 203
A supply / discharge passage 205 connecting the cylinder 202 to the cylinder 202, an outlet flow passage 206 connecting the directional control valve 203 to an external fluid discharge passage,
One plunger type pump 207 driven by the cylinder 202 is provided (see Japanese Patent Publication No. 55-40761 and Japanese Patent Publication No. 59-25081).

[0004]

In this conventional fluid pump driven by pressure, since there is only one cylinder 202 and one pump 207 driven by the cylinder, the discharge pressure of the pump is, as shown in FIG. In this case, the discharge pressure of the working fluid becomes 0 (or the internal pressure of the discharge flow path), and in the discharge stroke, the discharge pressure largely pulsates between 0 (or the internal pressure of the discharge flow path) and the maximum discharge pressure. As a result, the stability of the operation of the pressure fluid device connected thereto may be impaired. Also, 1
Since the discharge amount per cycle is small, it is disadvantageous, for example, in improving the startup characteristics at the start.

The present invention has been made in view of the above circumstances, and has as its object to provide a pressure-fluid-driven pump capable of reducing the pulsation of the discharge pressure and increasing the discharge amount. It is.

[0006]

SUMMARY OF THE INVENTION The present invention provides a single-acting cylinder driven by a pressure fluid in a body, a directional control valve for controlling the supply and discharge of the pressure fluid to and from the cylinder, and an external pressure fluid supply. An inlet passage connecting the passage to the directional control valve, a supply / discharge passage connecting the directional control valve to the cylinder, an outlet passage connecting the directional control valve to the external fluid discharge passage, and driven by the cylinder In a pressure fluid driven pump including a plunger type pump, the following measures are taken to achieve the above object.

That is, two cylinders and two pumps driven by each cylinder are provided in the body, and the discharge paths of both pumps are merged downstream of the outlet check valve. When the pressure fluid is supplied to the discharge driving pressure receiving chamber of the cylinder, the pressure fluid in the discharge driving pressure receiving chamber of the other cylinder is discharged, and when the pressure fluid is discharged from the discharge driving pressure receiving chamber of one cylinder, the pressure of the other cylinder is discharged. A directional control valve for supplying a pressure fluid to the discharge driving pressure receiving chamber is provided.

[0008]

In the present invention, since the two cylinders and the pump operate simultaneously while taking opposite strokes,
During one cycle, once from each pump, and while the discharge is stopped in the suction stroke of one pump, the discharge is performed from the other pump. Can be reduced.

In addition, since the two pumps discharge the pressurized fluid during one cycle, the discharge amount can be increased, for example, twice.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the sectional views of FIGS. 1 and 2. The pressure fluid driven pump according to this embodiment is, for example, an overload of a machine tool. It is used for a booster pump of a safety device, and is configured to use compressed air as a pressure fluid as a driving source and discharge oil as a working fluid.

In a body 1 of the pressure fluid driven pump, two single-acting cylinders 2 driven by compressed air are provided.
a, 2b, a directional control valve 3 for controlling the supply and discharge of compressed air to and from these cylinders 2a, 2b, an inlet flow path 4 for connecting an external pressure fluid supply path to the directional control valve 3, and a directional control valve. Supply / discharge path 5 for individually connecting the cylinders 3 to the cylinders 2a and 2b
a, 5b, an outlet flow path 7 connecting the directional control valve 3 to an external fluid discharge path 6, and two plunger pumps 8a, 8b individually driven by the cylinders 2a, 2b.

Each of the cylinders 2a and 2b includes a cylindrical cylinder chamber 21a and 21b, and pistons 22a and 22b hermetically fitted in the cylinder chambers 21a and 21b so as to advance and retreat. Are divided by the pistons 22a and 22b into variable volume spring chambers 23a and 23b on the pump 8a and 8b side and variable volume pressure receiving chambers 24a and 24b on the opposite side.
Further, return springs 25a and 25b are inserted into the spring chambers 23a and 23b to push the pistons 22a and 22b back toward the pumps 8a and 8b, that is, toward the direction control valve 3.

The directional control valve 3 discharges the pressure fluid of the other cylinder (hereinafter, referred to as a second cylinder) 2b when the pressure fluid is supplied to one of the cylinders (hereinafter, referred to as a first cylinder) 2a. The configuration is not particularly limited as long as the pressure fluid is supplied to the second cylinder 2b when the pressure fluid is discharged from the cylinder 2a. For this purpose, the directional control valve 3 needs to be configured such that the connection direction is reversed at the end of the stroke of one of the cylinders 2a or 2b.
For example, a case where a and the main valve element of the direction control valve 3 are linked will be described below.

That is, the main valve 3a for controlling the connection direction of the pressure fluid to the direction control valve 3, and the piston 22 of the cylinder 2a
The main valve drive means 3b for switching the position of the valve (main valve) of the main valve at both stroke ends of the piston 22a in conjunction with the position a is provided. Although the main valve 3a may be constituted by a poppet type valve, in this embodiment, it is constituted by a spool type valve which can make the driving force relatively small. That is, the main spool 32a is slidably inserted into the cylindrical main valve chamber 31a. The main valve chamber 31a is arranged coaxially with the cylinder 2a on the side of the pressure receiving chamber 24a of the cylinder 2a in order to make the whole small and compact.

On the other hand, in order to realize the connection switching as described above, on the other hand, the cylinder 2a is mounted on the peripheral surface of the main valve chamber 31a.
From the side, the inlet flow path 4, the supply / discharge path 5 of the first cylinder 2a
a, a supply / discharge passage 5b of the second cylinder 2b and a branch flow passage 4a connecting the inlet passage 4 to the supply / discharge passage 5b of the second cylinder 2b are opened at appropriate intervals. On the other hand, an exhaust hole 33a communicating with the outlet flow path 7 is recessed into the center of the main spool 32a from the end face on the side opposite to the cylinder 2a, and the first cylinder 2a is sequentially arranged on the outer periphery from the cylinder 2a side.
Circumferential groove 34 for interrupting the connection between the supply / discharge path 5a and the inlet flow path 4
a, the supply / discharge path 5a of the first cylinder 2a and the second cylinder 2b
And a circumferential groove 36a for switching connection to the exhaust hole 33a through the through hole 35a, and a circumferential groove 37a for interrupting connection between the branch flow path 4a and the supply / discharge path 5b of the second cylinder 2b. You.

The main spool 32a is connected to the opposite cylinder 2a.
1, the inlet passage 4 is connected to the supply / discharge passage 5a of the first cylinder 2a through the circumferential groove 34a, and the supply / discharge passage 5b of the second cylinder 2b
Is connected to the outlet channel 7 via the circumferential groove 36a, the through hole 35a, and the exhaust hole 33a. The main spool 32a is connected to the cylinder 2
When located at the stroke end on the side a, as shown in FIG. 2, the inlet flow path 4 includes the circumferential groove 34a, the branch flow path 4a, and the circumferential groove 37a.
Is connected to the supply / discharge path 5b of the second cylinder 2b, and the supply / discharge path 5a of the first cylinder 2a is connected to the outlet flow path 7 via the circumferential groove 36a, the through hole 35a, and the exhaust hole 33a.

The outlet channel 7 is connected to the atmosphere via a silencer 9. The main valve drive means 3b may be configured to switch the position of the main spool 32a at both stroke ends of the piston 22a. For example, a return cylinder 31b is provided on one side of the main valve chamber 31a. The piston 32b of the return cylinder 31b is connected to the main spool 32a, and the pressure receiving chamber 33b on the main valve chamber 31a side of the return cylinder 31b is always in communication with the inlet flow path 4 via the circumferential groove 34a of the main spool 32a. A spool 35b for switching and connecting the pressure receiving chamber 34b on the first cylinder 2a side to the inlet flow path 4 and the outlet flow path 7 is provided, and the piston 22a of the first cylinder 2a
b is driven so that its position is inverted.

That is, as shown in FIG.
When a reaches the stroke end on the directional control valve 3 side,
The spool 35b is pushed out to the direction control valve 3 side, the pressure receiving chamber 34b on the first cylinder 2a side of the return cylinder 31b is connected and switched to the inlet flow path 4, and the piston 32b and the main spool 32a are moved to the side opposite to the first cylinder 2a. Be moved.
As shown in FIG. 2, the piston 22a is connected to the pump 8a.
When the stroke reaches the stroke end, the spool 35b is drawn toward the first cylinder 2a, and the return cylinder 31b
The pressure receiving chamber 34b on the first cylinder 2a side is connected and switched to the outlet flow path 7, and the piston 32b and the main spool 32
a is moved to the first cylinder 2a side.

The pumps 8a and 8b are provided with pump chambers 81a and 81a arranged coaxially with the first and second cylinders 2a and 2b.
81b, pressure oil suction passage 82a connected to pump chambers 81a and 81b
・ Inlet check valves 83a and 83b for opening and closing 82b, inlet check valve 83
valve closing springs 84a and 84b for urging the valves a and 83b to close the valve;
Outlet check valves 86a and 86b for opening and closing discharge passages 85a and 85b derived from 81a and 81b, and valve closing springs 87a and 87b for closing and urging the outlet check valves 86a and 86b, and pistons 22a and 22b.
And plungers 88a and 88b that enter and exit the respective pump chambers 81a and 81b.

The discharge passages 85a and 85b of the two pumps 8a and 8b join each other downstream of the outlet check valves 86a and 86b so that the pressure oil is discharged from one discharge port 89. In this pressure fluid driven pump, as shown in FIG.
When the piston 2 of the cylinder 2a is located at the stroke end on the direction control valve 3 side, the spool 35b is pushed out to the direction control valve 3 side. Thus, the first cylinder 31b
The connection of the pressure receiving chamber 34b on the cylinder 2a side to the inlet flow path 4 is switched, the internal pressure of the pressure receiving chamber 34b is increased, and the main spool 32a is
The pistons 22a and 22b and the main spool 32a are moved to the side opposite to the first cylinder 2a due to the differential pressure from the atmospheric pressure acting on the end face on the side opposite to the first cylinder 2a. As a result, compressed air flows into the pressure receiving chamber 24a of the first cylinder 2a from the inlet channel 4 via the circumferential groove 34a and the supply / discharge path 5a, and the return spring 25a
The piston 22a is moved to the pump 8a side against the pressure, and the pump 8a discharges the pressure oil.

On the other hand, the pressure receiving chamber 24b of the second cylinder 2b is communicated with the atmosphere via the supply / discharge path 5b, the circumferential groove 36a, the through hole 35a, the exhaust hole 33a and the outlet passage 7, so that the pressure receiving chamber 24b The pressure is reduced to atmospheric pressure, the piston 22b is driven by the return spring 25b toward the opposite side of the pump 8b, and the working oil is sucked into the pump chamber 81b of the pump 8b from the pressure oil suction passage 82b via the inlet check valve 83b.

Thereafter, when the piston 2 of the first cylinder 2a moves to the stroke end on the pump 8a side, the spool 35b is drawn toward the pump 8a. This allows
The pressure receiving chamber 34b on the first cylinder 2a side of the return cylinder 31b is connected and switched to the outlet flow path 7, the internal pressure of the pressure receiving chamber 34b is reduced to the atmospheric pressure, and the direction control valve 3 of the return cylinder 31b is changed.
The pressure difference between the pressure receiving chamber 33b on the side and the pressure receiving chamber 34b on the first cylinder 2a moves the piston 32 and the main spool 32a toward the first cylinder 22a. As a result, the inlet channel 4
From the circumferential groove 34a, the branch channel 4a, the circumferential groove 37a and the supply / discharge path 5
b, the compressed air flows into the pressure receiving chamber 24b of the second cylinder 2b, and pushes the piston 22b into the pump 8 against the return spring 25b.
b, and the pressure oil is discharged from the pump 8b.

On the other hand, the pressure receiving chamber 24 of the first cylinder 2a
a is communicated with the atmosphere via a supply / discharge passage 5a, a circumferential groove 36a, a through hole 35a, an exhaust hole 33a, and an outlet flow path 7;
As a result, the piston 22a is driven toward the side opposite to the pump 8a, and hydraulic oil is sucked into the pump chamber 81a of the pump 8a from the pressure oil suction passage 82a via the inlet check valve 83a. In this way, as shown in FIG. 3, while the discharge of one pump 8a or 8b is stopped during one cycle, the other pump 8a is stopped.
Since the pressure oil is discharged from b or 8a, pressure fluctuation of the discharge pressure can be reduced.

In one cycle, two pumps 8a
Since the hydraulic oil is discharged from each of the nozzles 8b, the discharge amount per cycle increases, and for example, the startup characteristics at the start can be improved. In the above embodiment,
Each of the cylinders 2a and 2b for driving the pumps 8a and 8b is constituted by a single-acting cylinder.
It is also possible to configure b with a backward-acting cylinder. In this case, even if the pressure receiving chambers for discharge driving of the cylinders 2a and 2b and the pressure receiving chambers for suction driving of the other cylinders 2b and 2a communicate with each other, another directional control valve is provided to The supply and discharge of the driving fluid to and from the pressure receiving chambers for suction driving of the cylinders 2a and 2b may be configured to be controlled.

[0025]

As described above, in the present invention, two cylinders and two pumps driven by each cylinder are provided in the body, the discharge paths of both pumps are joined, and the directional control valve is provided. A directional control valve is provided for discharging the pressure fluid of the other cylinder when the pressure fluid is supplied to one cylinder and supplying the pressure fluid to the other cylinder when the pressure fluid is discharged from the one cylinder.

Thus, while the discharge of one pump is stopped, the working fluid is discharged from the other pump, so that there is no period in which the discharge pressure is maintained at 0 or the minimum discharge pressure, and the fluctuation of the discharge pressure is reduced. Become. Further, since the working fluid is discharged once from each of the two pumps during one cycle, the discharge amount per cycle can be increased, and the rising characteristics can be improved. The present invention
Since the spool is used for switching the directional control valve, the directional control valve can be switched reliably and smoothly at both stroke ends of the piston in conjunction with the piston of the cylinder.

[Brief description of the drawings]

FIG. 1 is a sectional view of the present invention.

FIG. 2 is a sectional view of the present invention.

FIG. 3 is a discharge pressure diagram of the present invention.

FIG. 4 is a configuration diagram of a preload-type overload safety device for a press.

FIG. 5 is a sectional view of a conventional example.

FIG. 6 is a discharge pressure diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Body 2a ... 1st cylinder 2b ... 2nd cylinder 3 ... Direction control valve 4 ... Inlet flow path 5a ... Supply / discharge path 5b ... Supply / discharge path 6 ... Fluid discharge path 7 ... Outlet flow path 8a ... Pump 8b ... Pump 24a ... pressure receiving chamber 24b ... pressure receiving chamber 85a ... discharge path 85b ... discharge path 86a ... outlet check valve 86b ... outlet check valve

Claims (1)

(57) [Scope of request for utility model registration] 1. A main spool controlling two single-acting cylinders (2a, 2b) driven by a pressure fluid in a body (1) and controlling the supply and discharge of the pressure fluid to and from the cylinders (2a, 2b). (32a) and a directional control valve (3) including a piston (32b); an inlet flow path (4) connecting an external pressure fluid supply path to the directional control valve (3); and a directional control valve (3).
Is connected to the cylinders (2a and 2b) (5a
5b), an outlet flow path (7) connecting the directional control valve (3) to an external fluid discharge path, and a piston (22a) of the directional control valve (3) and the cylinder (2a). The spool (35b), the plunger pumps (8a, 8b) driven by the cylinders (2a, 2b), and the pump check chambers (81a, 81b) of the pumps (8a, 8b) have inlet check valves (83a, 83a). 83b) and the pump chamber (81
a, 81b) with a pressure oil suction passage (82a, 82b) connected via an inlet check valve (83a, 83b), and an outlet check for the hydraulic discharge passage (89) of both pumps (8a, 8b). A pressure fluid driven pump that joins as a discharge port (89) downstream of the valves (86a and 86b),
2a) is provided with a piston (32b) at one end, and a main spool (32a) is provided in the main valve chamber (31a).
b) are slidably inserted into the double-acting cylinders (31b), respectively.
b) a circumferential groove (34) for interrupting the connection between the inlet channel (4) and
a.36a) are provided around the main spool (32a), and the directional control valve (3) is used to switch the supply and discharge of the pressure fluid to be applied to the piston (22a).
2b), the pressure fluid is supplied to the discharge driving pressure receiving chamber (24b) of the second cylinder (2b) when the pressure fluid is supplied to the discharge driving pressure receiving chamber (24a) of the first cylinder (2a). Directional control valve for discharging the pressure fluid and supplying the pressure fluid to the discharge drive pressure receiving chamber (24b) of the second cylinder (2b) when the pressure fluid is discharged from the discharge drive pressure receiving chamber (24a) of the first cylinder (2a). (3), spool (35
b) to the main spool (32a) and the pressure receiving chamber (34).
b) is switched between the inlet channel (4) and the outlet channel (7) so as to be connectable, and the piston (22) of the first cylinder (2a) is connected.
a) reverses the position of the spool (35b) at both ends of the stroke, and the piston (22a) of the cylinder (2a)
The position of the directional control valve (3) is switched at both stroke ends of the piston (22a) in conjunction with the movement of the piston (22a), and the piston (22a) of the first cylinder (2a) is positioned at the stroke end on the directional control valve (3) side. Then, the spool (35b)
Is pushed out to the direction control valve (3) side, and the piston (32
b) The pressure receiving chamber (34b) on the side of the first cylinder (2a) is connected and switched to the inlet flow path (4), the internal pressure of the pressure receiving chamber (34b) is increased, and the piston (32b) is opposed to the first cylinder (2a). ) Side end face due to the differential pressure acting on the piston (3
2b) and the main spool (32a) are moved toward the side opposite to the first cylinder (2a), and are moved from the inlet flow path (4) to the circumferential groove (34).
a) and the first cylinder (2) via the supply / discharge path (5a).
The pressure fluid flows into the pressure receiving chamber (24a) of (a), and the piston (22a) is pumped (8) against the return spring (25a).
a) side, and from the pump (8a) to the discharge port (89)
The pressure receiving chamber (24b) of the second cylinder (2b) is provided with a supply / discharge path (5b), a circumferential groove (36a),
It communicates with the atmosphere through the outlet channel (7), and is connected to the pressure receiving chamber (24).
The pressure of b) is reduced to the atmospheric pressure, and the piston (22b) is driven by the return spring (25b) to the side opposite to the pump (8b), and the pressure oil suction passage (82b) is supplied to the pump chamber (81b) of the pump (8b). Hydraulic oil is sucked through the inlet check valve (83b), and thereafter, the piston (22a) of the first cylinder (2a) is drawn toward the pump (8a), and the first cylinder (2a) of the piston (32b) is drawn. ) Side pressure receiving chamber (34
b) is connected and switched to the outlet flow path (7), the internal pressure of the pressure receiving chamber (34b) is reduced to atmospheric pressure, and the piston (32)
The piston (32b) and the main spool (32a) move toward the first cylinder (2a) due to the pressure difference between the directional control valve (3) and the directional control valve (3), and the circumferential groove (34) moves from the inlet flow path (4).
a), the pressure fluid flows into the pressure receiving chamber (24b) of the second cylinder (2b) via the supply / discharge path (5b), and the return spring (25)
b), the piston (22b) is moved to the pump (8b) side, and pressure oil is discharged from the pump (8b) through the discharge port (89), while the pressure receiving chamber (1) of the first cylinder (2a) is moved. 24a) is communicated with the atmosphere via a supply / discharge path (5a), a circumferential groove (36a) and an outlet flow path (7), and a return spring (2).
5a) causes the piston (22a) to be turned into an anti-pump
Hydraulic fluid is driven into the pump chamber (81a) of the pump (8a) and hydraulic oil is sucked into the pump chamber (81a) from the pressure oil suction passage (82a) through the inlet check valve (83a). Type pump.