JPS639704A - Suction mechanism in hydraulic booster - Google Patents

Abstract

PURPOSE:To make a suction pump compact and light, by forming a suction piston of the suction pump into a two-step structure having a small-diameter stepped portion, and providing a slight time difference in operation timing of the suction pump when a high-pressure electromagnetic selector valve is opened. CONSTITUTION:A suction pump 6 is formed by a drive cylinder 40A and a suction cylinder 40B. A suction piston 44 is integrally formed with a small- diameter suction piston 45. The piston 45 is closely engaged in a small-diameter cylinder 47. In driving the suction pump, selecting operations of a high-pressure solenoid valve 26 and a low-pressure solenoid valve 4 are conducted with a time difference, and a suction start timing of the suction pump 6 is given a time difference when the high-pressure solenoid valve 26 is opened. Accordingly, it is possible to decrease a load due to a rapid pressure fluctuation at the suction timing, thereby increasing the rigidity of the pump. Further, as a permissible suction quantity of the suction pump may be effectively utilized, the suction pump may be made compact and light.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a hydraulic booster that serves as a hydraulic power source for a hydraulic tool.
In particular, the present invention relates to a hydraulic booster with an improved suction mechanism for returning hydraulic oil to a hydraulic tool.

[Conventional technology]

Conventionally, when this type of hydraulic booster supplies pressure oil to a hydraulic tool and returns the hydraulic oil after completing work, it uses the spring force of a return spring built into the tool's single-acting hydraulic cylinder, or the pressure booster pump itself. was performed by suctioning. This method has the problem that the return speed is slow in the former case (and the pump becomes large in the latter case, and this tendency is particularly noticeable when the tool has a large cylinder or the hydraulic hose is long).

In order to solve this problem, it is effective to provide a dedicated suction pump in the hydraulic circuit of the hydraulic booster. The booster is disclosed.

[Problem that the invention seeks to solve]

However, in the hydraulic booster equipped with the suction pump described above, when the high-pressure switching valve interposed between the hydraulic tool and the suction pump opens, sudden pressure fluctuations act on the suction pump, and this directly affects the suction cylinder and the suction pump. Since the structure acted on the piston, it was necessary to increase the strength and rigidity of each component such as the cylinder and piston for safety reasons. Therefore, it has not been possible to reduce the size and weight, leading to high costs. In addition, since the suction pump was configured to operate at the same time as the switching valve opened, when the cylinder of a hydraulic tool is large or the pressure booster hose is expanded for a long time, the suction cylinder will be activated due to the increase in hydraulic oil capacity. There was a problem in that capacity was insufficient and the return of hydraulic fluid from the hydraulic tool was delayed due to residual back pressure (residual pressure) in the circuit.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention improves the suction mechanism of the conventional booster, shortens the return speed of the hydraulic oil of the hydraulic tool, reduces the size and weight of the suction pump, and provides a durable hydraulic system. It was developed for the purpose of providing a booster, and its specific means include a low pressure switching valve connected to a hydraulic source, a pressure booster pump connected to the low pressure switching valve, and a booster pump connected to the low pressure switching valve. In a hydraulic booster equipped with a pressure switch and a high pressure switching valve connected to the discharge side, and a suction pump etc. connected to the high pressure switching valve, the suction side cylinder of the suction pump has a large diameter part and a small diameter part. A stepped suction piston is inserted, and the small diameter suction piston fits and slides with a small diameter cylinder of a suction block provided on one side of the cylinder, and the small diameter cylinder and the suction side cylinder are connected to the high pressure switching valve. This is constructed as a suction mechanism in a hydraulic booster characterized in that it is connected to a communicating circuit and that a time difference is provided in the suction start timing of the suction pump when the high-pressure switching valve is opened.

[Effect]

According to the suction mechanism configured as described above, the high pressure switching valve is opened by the operation of the pressure switch, a part of the high pressure hydraulic oil that was being supplied to the hydraulic tool is discharged, and at the same time, after a certain period of time has elapsed since the high pressure switching valve was opened, the high pressure switching valve is opened. Suction by the pump begins to suck the hydraulic fluid in the hydraulic tool and circuit. In addition, the sudden pressure fluctuations caused by the opening of the high-pressure switching valve are absorbed by the small-diameter cylinder and small-diameter suction piston, which have a small area.
The pressure load on the suction side is reduced.

〔Example〕

An embodiment of the present invention will be described below based on the drawings. 1st
The figure shows the entire configuration of the hydraulic booster using a circuit diagram, and l denotes a hydraulic power source, which is connected to a vehicle equipped with a hydraulic power source, such as an aerial work vehicle or a crane vehicle (not shown). This hydraulic power source 1 is provided with a circuit 5 connected to a low pressure solenoid switching valve (hereinafter referred to as low pressure solenoid valve) 4 via quick couplings 2A, 2B and a filter 3, and the low pressure solenoid valve 4 has a suction pump 6.
A circuit 8 is provided which connects to the first oil chamber 7A on the right side formed in the drive side cylinder 6A (details will be described later), and a circuit 11 which returns the oil to the external oil tank 10 via the check valve 9. . Furthermore, the main circuit 12 connected to the low pressure solenoid valve 4 includes a circuit 16A connected to the secondary oil chamber 15 of the booster pump 14 via a check valve 13, and a switching circuit 16A that is connected to the secondary oil chamber 15 of the booster pump 14. A branched circuit 16B leading to the valve 17 is provided. The switching valve 17 and the pressure booster pump 14 are connected to a left primary oil chamber 19A and a right return oil chamber 1, with the piston 18 of the pressure booster pump 14 in between.
The switching valve 17 switches the oil passage in conjunction with the movement of the piston 18, thereby causing the piston 18 to reciprocate.

Therefore, the hydraulic oil also flows in both directions as shown by the arrows in the figure. Further, the hydraulic oil discharged from the switching valve 17 is supplied to the circuit 21.
The oil is returned to the oil tank 10.

On the other hand, a pressure booster circuit 23 is connected to the secondary oil chamber 15 of the pressure booster pump 14 via a check valve 22A, quick joints 22B and 22C, and a hydraulic tool 24 is connected to the end of this circuit 23. Ru.

A circuit 27 that connects to a pressure switch 25 and a high-pressure electromagnetic switching valve (hereinafter referred to as high-pressure electromagnetic valve) 26 is provided in the middle of the pressure increase circuit 23, and a circuit 27 is branched from the high-pressure electromagnetic valve 26 through a check valve 28. A circuit 30 is provided which connects to a small diameter cylinder 29 on the suction side of the suction pump 6, which will be described later, and a check pulp 31 is connected to the small diameter cylinder 29.
A circuit 32 is formed which leads to the oil tank 10 via.

By the way, the main circuit 12 includes a check pulp 33.
A circuit 34 communicating with a second hydraulic pressure 7B formed in the drive side cylinder 6A of the suction pump 6 is connected through the
Also, from this circuit 34, the biloft check pulp 35
A branched circuit 36 is provided which connects to the oil tank 10 via.

Reference numeral 37 is a microswitch that comes into contact with a driving piston of a suction pump 6, which will be described later.

Next, the configuration of the suction pump 6 will be described in detail with reference to FIG.

Note that new symbols are added. The suction pump 40 is formed by a drive-side cylinder 40A on the left side in the figure and a suction-side cylinder 40B with a slightly larger diameter on the right side with a center block 41 in the approximately central portion in between. A piston shaft 42 is installed inside the block 41, and on the left side of this shaft 42 is a drive side cylinder 40A.
A drive piston 43 is fixed to the right side of the cylinder 40B, and a large-diameter suction piston 44 is fixed to the right side of the suction side cylinder 40B. Also, the suction piston 44
A step is formed at the end, and a small-diameter suction piston 45 is integrally provided.

This piston 45 is tightly fitted into a small diameter cylinder 47 formed at the center of a suction block 46 fixed to the base end of the suction side cylinder 40B. The suction block 46 is formed with an oil passage 48 that leads to the high-pressure solenoid valve 26 and the oil tank 10 shown in FIG.
7, the other side communicates with the main suction oil chamber 40C between the suction piston 44 and the suction block 46.

On the other hand, a drive piston 43 is provided in the drive side cylinder 40A.
A first oil chamber 49 is formed between the center block 41 and the center block 41,
This oil chamber 49 is an oil passage 5 formed in the center block 41.
0 to the low pressure solenoid valve 4 shown in FIG.
Hydraulic oil is sucked and discharged. Also, a drive block 51 and a drive piston 4 fixed to the base end of the drive side cylinder 40A.
A second oil chamber 52 is formed between the drive block 51 and the first oil chamber 52 through an oil passage 53 formed in the drive block 51.
It is connected to the main circuit 12 between the low pressure solenoid valve 4 and the pressure booster pump 14 shown in the figure.

At the center of the drive block 51, that is, at a position facing the piston shaft 42, a pin 54 is slidably provided with one end thereof located within the second oil chamber 52 and with a return spring 55 interposed therebetween. , the piston shaft 42 comes into contact with the piston shaft 42 when it reaches the stroke end. A plate 56 is attached to the left end of this pin 54, and a microswitch 57 (37 in FIG. 1) as shown by the two-dot chain line comes into contact with this plate 56 to generate a signal. .

Incidentally, since the air chamber 58 formed between the suction piston 44 and the center block 41 communicates with the atmosphere through an air hole 59 formed in the center block 41, it does not interfere with the movement of the piston.

In addition, the drive side cylinder 40A and the suction side cylinder 40
Block 41.4 in contact or sliding contact with the inner peripheral surface of B
6.51 and the circumferential surfaces of the pistons 43 and 44 are fitted with O-rings 60, 60, etc. to prevent oil leakage.Furthermore, O-rings 60, 60... A ring 61 is fitted to prevent oil from entering the air chamber 58.

Next, the operation of the above embodiment will be explained.

In FIG. 1, first, when increasing the pressure of oil from the hydraulic source 1 to the pressure required for work and supplying it to the hydraulic tool 24, the low pressure solenoid valve 4 is activated by an electric signal from a control device (not shown).
Switch to position. Then, the hydraulic fluid from the hydraulic source 1 passes through the quick couplings 2A, 2B and the filter 3, reaches the low pressure solenoid valve 4, and from there passes through the main circuit 12 to the secondary oil chamber 15 of the pressure booster pump 14 and the switching valve 17. supplied to

The hydraulic oil supplied to the switching valve 17 is in the circuit 20A.

Oil is alternately supplied to either the primary oil chamber 19A or the return oil chamber 19B of the pressure booster pump 14 via the oil pump 20B, thereby reciprocating the piston 18. When hydraulic oil is sent to the primary oil chamber 19A, it is first returned and the oil flowing into the oil chamber 19B is discharged to the oil tank 10 side, and at the same time, it flows into the secondary oil chamber 15 in the previous stroke. Increase the pressure of the hydraulic oil that is
Discharge to the side. Also, when oil is sent to the return oil chamber 19B,
The hydraulic oil in the primary oil chamber 19A is discharged to the oil tank 10 side, and low pressure oil from the hydraulic source 1 is sucked into the secondary oil chamber 15 again. This hydraulic oil switching operation is performed by the pressure booster piston 1.
This is done by automatically switching the oil passage of the switching valve 17 in conjunction with the displacement amount of the pressure boosting piston 18.

Therefore, as long as the supply of hydraulic oil to the switching valve 17 continues, the pressure boosting piston 18 continues to reciprocate, and the secondary oil chamber 15 repeatedly sucks and discharges hydraulic oil, gradually increasing the oil pressure. It will be done. The high pressure oil is then forced to be fed to the hydraulic cylinder of the hydraulic tool 24 via the pressure increase circuit 23. This pressure oil is simultaneously supplied to a pressure switch 25 and a high pressure solenoid valve 26 from a circuit 27 branched from the pressure booster circuit 23.
However, since the high-pressure solenoid valve 26 is in the A position and the oil passage on this side is closed, hydraulic oil will not flow into the subsequent circuit. Therefore, pressure oil is reliably supplied to the hydraulic tool 24 side.

The pressure booster pump 14 is of a known mechanism that increases the pressure based on the difference in the ratio of pressure receiving areas between the primary and secondary pistons.

On the other hand, the hydraulic oil from the hydraulic pressure source 1 is supplied to the suction pump 40 shown in FIG. 2 (in FIG.
) is supplied to the second oil chamber 52 (7B in FIG. 1) from the oil passage 53 formed in the drive block 51 of the piston 43 and the piston shaft 42.
The suction piston 44 and the small-diameter suction piston 45, which are integrated with each other, are slid to the right in the figure, and the hydraulic oil that was sucked into the main suction oil chamber 40G and the small-diameter cylinder 47 in the previous stroke is removed from the oil passage 48. It is discharged to the oil tank 10 side through the circuit 32 shown in FIG.

At the same time, the first oil chamber 49 (
Hydraulic oil supplied to 7A) in FIG. 1 is discharged from an oil passage 50 formed in the center block 41 to the oil tank 10 via the circuit 8 and low-pressure solenoid valve 4 shown in FIG. The suction pump 40 can prepare for the next suction operation by the above operation.

Next, the suction effect of pressure oil from the hydraulic tool 24 will be explained.

After the work with the hydraulic tool 24 is completed, the pressure booster pump 14
If the pressure continues to increase, the pressure switch 2 is connected to a circuit 27 branched from the pressure increase circuit 23 and set to a predetermined pressure.
5 is activated, and this electric signal switches the high-pressure solenoid valve 26 to the B position and opens it. Accordingly, the pressure of the hydraulic oil in the hydraulic cylinder of the hydraulic tool 24 and the pressurized circuit is suddenly reduced, and a portion of the hydraulic oil is directly discharged into the oil tank 10. At the same time, immediately after the high-pressure solenoid valve 26 opens (after approximately 0.5 seconds), the low-pressure solenoid valve 4 is switched to the C position and the suction pump 6 is operated.

By setting a time difference in this switching operation, even if the hydraulic hose between the pressure booster pump 14 and the hydraulic tool 24 is long and the hose expands and the amount of oil increases, the oil corresponding to this expansion can be absorbed through the suction pump 6. A portion of the oil can be discharged into the oil tank 10 without any oil leakage. Therefore, there is no need to increase the suction capacity of the suction pump 6, and the size and weight of the suction pump 6 can be reduced.

When the low pressure solenoid valve 4 switches to the C position, the hydraulic power source 1
The hydraulic oil flows through the circuit 8 into the first oil chamber 49 of the suction pump 40 shown in FIG. 2, causing the drive piston 43 and the suction piston 44 to slide to the left in the figure. At the same time, the biloft check valve 35 shown in FIG. 1 is opened, and the hydraulic oil that has flowed into the second oil chamber 52 in the previous stroke is discharged to the oil tank IO. As the suction piston 44 operates, the hydraulic tool 24 and the hydraulic oil in the pressure increase circuit are suctioned into the main suction oil chamber 40C and the small diameter cylinder 47. During this suction, rapid pressure fluctuations accompanying the opening of the high-pressure solenoid valve 26 act on the suction side, but the small-diameter suction piston 45
By providing a small-diameter cylinder 47 that fits therewith to reduce the area subject to initial pressure fluctuations, it is temporarily buffered and the load on the suction side can be reduced.

On the other hand, when the suction piston 44 reaches the stroke end, the end of the piston shaft 42 located on the opposite side presses the pin 54 provided on the drive block 51, and the plate 56 connected to this pushes the micro switch. 57 is activated. As a result, a signal indicating the end of suction is sent to a control circuit (not shown), and after a certain period of time (approximately 10 to 12 seconds) has elapsed, the high-pressure solenoid valve 26 is returned to the A position. By increasing and decreasing the pressure of the hydraulic oil as described above, the hydraulic cylinder of the hydraulic tool 24 has completed one cycle of the expansion and contraction stroke.

Note that by delaying the switching operation of the high-pressure solenoid valve 26 for a certain period of time, the cylinder capacity of the hydraulic tool 24 is increased (so that even if the returned amount of hydraulic oil exceeds the suction capacity of the suction pump 40, the hydraulic tool 24 is The built-in return spring allows the hydraulic oil to be discharged by the blade itself.Therefore, the capacity of the secondary discharge oil amount of the pressure booster pump 14 can be increased, and it can also be used with large hydraulic tools.

Additionally, if you want to stop the pressure increase before reaching the set pressure of the pressure switch 25 during the pressure increase, if you switch the low pressure solenoid valve 4 from the A position to the B position, the hydraulic fluid from the hydraulic source 1 will pass through the check valve 9. The oil is returned to the oil tank 10, and the oil pressure in the circuit beyond the low-pressure solenoid valve 4 is maintained at the state immediately before switching to the B position, and pressure increase is stopped.

〔Effect of the invention〕

As is clear from the above description, the suction mechanism of the present invention provides the following effects.

(1) The suction piston of the suction pump has a two-stage structure with a small-diameter stepped portion, which reduces the load associated with rapid pressure fluctuations during suction and increases the strength and rigidity of the pump. Therefore, safety is high, the pump can be made smaller and lighter, and the durability of the pump can be improved.

(2) By slightly differentiating the operation timing of the suction pump when the high-pressure solenoid switching valve opens, the initially high-pressure hydraulic oil is discharged without going through the pump, so the hydraulic hose is long and the hydraulic Even if the cylinder capacity of the tool is large, the suction capacity of the suction pump can be effectively utilized, and therefore the suction pump can be made smaller and lighter. - (3) In addition, since the suction pump effectively sucks the hydraulic oil, residual back pressure in the pressure booster circuit is eliminated.
Therefore, the retraction speed of the cylinder of the hydraulic tool becomes faster, improving work efficiency.

[Brief explanation of the drawing]

The drawings relate to the present invention; FIG. 1 is a circuit configuration diagram of the entire hydraulic booster, and FIG. 2 is a vertical sectional view of the main part showing the structure of the suction pump. 1... Hydraulic power source 4... Low pressure solenoid switching valve 6
, (40)... Suction pump 14... Booster pump 17... Switching valve 24... Hydraulic tool 2
5... Pressure switch 26... High pressure electromagnetic switching valve 35... Viloft check valve 37 (57)... Micro switch 40A... Drive side cylinder 40B... Suction side cylinder 41...
Center block 43... Drive piston 44...
Suction piston 45...Small diameter suction piston 46.
・・Suction block 47・・Small diameter cylinder 49・
...First oil chamber 52...Second oil chamber 54...
·pin

Claims (1)

[Claims] A low-pressure switching valve connected to a hydraulic power source, a pressure booster pump connected to the low-pressure switching valve, a pressure switch and a high-pressure switching valve connected to the discharge side of the pressure booster pump, and a high-pressure switching valve connected to the high-pressure switching valve. In a hydraulic booster equipped with a suction pump or the like, a suction piston having a large diameter portion and a small diameter portion formed in a step is inserted into the suction side cylinder of the suction pump, and the small diameter suction piston is provided on one side of the cylinder. The small-diameter cylinder of the suction block fits and slides, and the small-diameter cylinder and the suction side cylinder are connected to a circuit leading to the high-pressure switching valve, and when the suction pump starts suction when the high-pressure switching valve opens. A suction mechanism in a hydraulic booster characterized by providing a time difference.