JPS5816991B2 - Switching spool valve for reciprocating piston of hydraulic impact machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spool valve for switching a piston reciprocating liquid supplied to a double-acting cylinder pressure chamber of a hydraulic impact machine.

Conventional hydraulic impact machines have low energy efficiency due to the low efficiency of the switching spool valve for piston reciprocation.

In other words, in the case of a hydraulic impact machine that reciprocates the piston via a spool valve, there is a phase difference between the piston displacement and the spool displacement, so the maximum piston speed (impact) is required to pass the maximum flow through the spool valve. (immediately before), the spool opening is rather small, so back pressure builds up, causing a reduction in the piston striking speed, that is, a reduction in striking efficiency.

This back pressure can be solved by enlarging the spool diameter and increasing the flow path area, but in this case, the weight of the spool increases, which actually hinders the high impact changes that are characteristic of hydraulic impact machines. This is an undesirable factor.

Further, in order to double the flow rate passing through the spool valve, the spool diameter must be doubled and the spool weight must be quadrupled, and there is a limit to reducing the back pressure by increasing the spool diameter.

Furthermore, aiming for high efficiency, an accumulator is provided on the rear chamber side of the cylinder to recover the energy of the return stroke and release it to the impact stroke, and the piston reciprocates by utilizing the difference in pressure receiving area between the front and rear chambers of the piston. In the case of this type of hydraulic impact machine, the amount of liquid required for one reciprocation of the piston must be discharged during the percussion stroke alone in order to increase the volume, so the amount of liquid that passes through the spool valve during the percussion stroke also doubles, reducing the back Although it is an excellent method in principle because the pressure increases further, side groups are not necessarily good.

An object of the present invention is to improve the energy efficiency of a hydraulic impact machine and to enable a higher number of blows by improving the spool valve.

The present invention provides a spool valve for a hydraulic impact machine, by providing a plurality of ports and unloading ports leading to the double-acting cylinder front chamber of the drilling tool impact piston, and providing a land portion on the spool for switching the ports. It is designed to have a large flow rate with a small valve size and spool weight.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

1 to 7 show an embodiment in which the spool valve of the present invention is applied to a rotary impact drill having a differential cylinder type hydraulic impact machine that switches the spool valve using an oscillator.

This rotary impact drill consists of a drill rotation mechanism section 1, a drill impact mechanism section 2, and a drill 3.1 The drill rotation mechanism section 1 includes a hydraulic motor 4, gears 5 to 7, a rotating sleeve with gears 8, and a hydraulic pressure source 9. , and a tank 10, and the drill 3 is fitted in a rotating sleeve 8 so that it can rotate and reciprocate at the same time.

FIG. 2 shows a partially enlarged view of the drill impact mechanism.

The drill impact mechanism section 2 includes a differential cylinder 11, a drill impact piston 12, a spool valve 13, an oscillator 14, an accumulator 15, a check valve 16, a hydraulic pressure source 17, and a tank 1.
8 and a flow path connecting these.

The piston 12 sliding within the cylinder 11 has two stepped portions 19 and 20, which together with the cylinder wall form a cylinder front chamber 21 and a cylinder rear chamber 22, respectively.

The diameter of the piston is smaller on the cylinder front chamber side than on the cylinder rear chamber side, and the pressure receiving area of the piston is larger on the cylinder front chamber side.

The airtightness of this cylinder is maintained by a piston bearing 23 having an airtight function.

The spool valve 13 is a 2-position, 3-port type, and has a spool 2 having three land portions 24, 25, and 26 inside.
7 slides.

The spool 27 has pilot pressure chambers 28 on both sides of the spool.
, 29 are maintained in the neutral position by springs 30, 3'l, respectively.

The oscillator 14 receives an appropriate supply of liquid from the flow path 32, supplies alternating hydraulic pressure to the pilot royal chambers 28 and 29 of the spool valve through the flow paths 33 and 34, and removes it by the reciprocating movement of the spool 27. The liquid is transferred to the flow path 34 again.
, 33, the liquid is returned to the oscillator, merged with the liquid consumed for oscillation, and unloaded from the flow path 35.

The fluid flow paths connecting the component devices are as follows.

That is, the cylinder rear chamber 22 is connected to the hydraulic pressure source 17 via a flow path 36 and a check valve 16, and the accumulator 15 is further connected to the flow path 36.

In this cylinder rear chamber 22, a port 37 for taking out a pilot pressure for piston displacement detection opens from the center and communicates with a pilot pressure chamber 28 of the spool valve via a flow path 38.

On the other hand, the cylinder front chamber 21 is connected to the cylinder front chamber port 39.40 of the spool valve, and communicates with the hydraulic pressure source 17 through the hydraulic pressure source port 41, or via the unload port 42.43.
unloaded by

Next, the operation will be explained.

Hereinafter, in any state, a pressure higher than the supply pressure is always applied to the cylinder rear chamber 22 due to the action of the check valve 16.

FIG. 2 shows the moment when the piston 12 hits the drill 3 and starts the return stroke.

At this time, the pressure of the cylinder rear chamber 22 acts on the pilot pressure chamber 28 via the port 37 in preference to the pilot pressure from the oscillator 14, so the spool 27 starts moving to the right in the figure. .

When moving this spool, first, the land portion 24 of the spool
closes the channel 42.

At this time, the cylinder front chamber 21 is unloaded through the ports 40 and 43, but is not communicating with the hydraulic pressure source 17 because the port 41 is still closed.

Then, as shown in FIG. 3, the cylinder front chamber 21 communicates with the hydraulic pressure source port 41 through the left end of the land portion 25.

At this time, the port 40 is not closed yet, so the cylinder front chamber 21 is simultaneously unloaded.

Finally, as shown in FIG. 4, the port 40 is closed by the right end of the land portion 25, completing the spool switching.

At this time, the entire supply pressure is applied to the cylinder front chamber 21 for the first time.
Although supply pressure is also applied to the cylinder rear chamber 22, the piston enters the return stroke due to the difference in pressure receiving area.

During this return stroke, the liquid in the cylinder rear chamber 22 that is displaced by the piston is stored in the accumulator 15.

When a force is applied to the spool 27 in the left direction in the figure by a signal from the oscillator 14, the port 40 is first opened by the right end of the land portion 25, contrary to the return stroke described above, and the cylinder front chamber 21 is unloaded. (Figure 5).

Then, the port 41 is closed by the left end of the land portion 25, and communication between the hydraulic pressure source and the cylinder front chamber 21 is cut off (FIG. 6).

Furthermore, the port 42 is opened by the land portion 50, spool switching is completed, and the cylinder front chamber 21 is opened by the spool valve 2.
It is unloaded by ports 42 and 43 at two locations (Figure 7).

At this time, since only back pressure is applied to the cylinder front chamber 21, the piston enters the striking stroke due to the supply pressure constantly applied to the cylinder rear chamber 22.

By repeating the above steps, the piston hits the drill continuously.

As described above, when the liquid discharged from the cylinder front chamber 21 passes through the spool during the impact stroke, the land portion 24.25
Because the air passes through two locations, back pressure is reduced.

Furthermore, when the spool is switched, the cylinder front chamber 21 is temporarily communicated with both the hydraulic pressure source and the tank due to the undercut, so it is possible to prevent an increase in back pressure caused by a phase difference between the spool switching timing and the piston displacement.

Next, a second embodiment of the present invention will be described.

Figures 8 to 10 show an embodiment in which the spool valve of the present invention is applied to a rotary impact drill having a differential cylinder type hydraulic impact machine that switches the spool valve depending on the piston position.

The difference from the previous embodiments shown in FIGS. 1 to 7 is that the spool valve is switched only by pilot pressure from the cylinder pressure chamber without using an oscillator.

Therefore, a cylinder center chamber 52 is formed in the center of the piston, which is always in communication with the tank through the port 51. On the other hand, depending on the piston position, the cylinder center chamber 52, the cylinder front chamber 21, the cylinder rear chamber 22 and the pilot pressure are alternately connected to each other. Channels 53, 54 are provided which communicate the chambers 29, 28.

Next, the operation will be briefly explained.

FIG. 9 shows a state in which the piston 12 hits the drill 3.

At this time, the pilot royal family 28 of the spool valve is connected to the flow path 54.
Since it communicates with the cylinder rear chamber 22 through the cylinder, high pressure is applied thereto.

On the other hand, since the pilot pressure chamber 29 on the opposite side is unloaded via the flow path 53 and the cylinder center chamber 52, there is only back pressure, and the spool 27 moves to the right in the figure.

The opening/closing order of each port during this spool movement is the same as in the above-mentioned embodiment.

When the spool switching is completed, the pressure in both the cylinder front chamber 21 and the cylinder rear chamber 22 becomes high, but the piston enters the return stroke due to the difference in pressure receiving area.

When the piston returns to the state shown in FIG. 10, the pilot pressure chamber 29 of the spool valve communicates with the cylinder front chamber 21 and becomes high pressure, while the pilot chamber 28 on the opposite side communicates with the cylinder center chamber 52 and creates back pressure. Therefore, the spool 27 moves to the left in the figure.

The opening and closing order of each port during this spool movement is the same as in the previous embodiment.

When the spool switching is completed, the cylinder front chamber 21 is unloaded, so the piston moves forward and enters the striking stroke.

By repeating the above steps, the piston hits the drill continuously.

Next, a third embodiment of the present invention will be described.

11 to 17 show an embodiment in which the spool valve of the present invention is applied to a rotary impact drill having a double-acting cylinder-type hydraulic impact machine that switches the spool valve using an oscillator.

The difference from the previous embodiments shown in FIGS. 1 to 7 is that the piston diameters of the double-acting cylinder are equal at the front and rear.

Therefore, there is no accumulator or check valve to store the energy for the return stroke (and the spool valve also changes the pressure on the cylinder rear chamber 22 side, so the structure of the spool valve is also different.

However, according to the present invention, an auxiliary flow path is added to the ordinary 2-position 4-port valve in order to smoothly flow the fluid discharged from the pressure chamber during the percussion stroke, which is the same as the above embodiment.

The internal structure of the spool valve 61 is shown in FIG.

The inside of this spool valve has four land parts 62, 63°64
．． A spool 66 with 65 slides.

The spool 66 has pilot pressure chambers 67 on both sides of the spool.
．． The neutral position is maintained by springs 69 and 70 provided at 68, respectively.

The pilot pressure chambers 67 and 68 of the spool valve are connected to the flow paths 33 and 3.
4 communicates with the oscillator 14.

Also, the spool valve and cylinder front chamber 21 are po)71.72
The spool valve and cylinder rear chamber 22 are connected to port 73 via
Through the spool valve and tank unload port 74
．． The spool valve and the hydraulic pressure source are connected via hydraulic source ports 77 via 75 and 76, respectively.

Furthermore, in order to regulate the stroke end when the piston retreats, when the piston retreats to a predetermined position, the cylinder front chamber 21
A port 78 in the center of the cylinder communicates with the tank so that the pressure can be released.

Next, the operation will be briefly explained.

FIG. 12 shows a state in which the piston 12 hits the drill 3 and is about to enter the return stroke.

At this time, when the pilot pressure from the oscillator 14 is applied to the pilot pressure chamber 67, the spool 66 starts moving to the right in the figure.

The opening and closing order of each port during this spool movement is the same as in the previous embodiment.

That is, first, the land portion 63 connects the cylinder front chamber 21 and the tank 1.
Close one unload port 75 communicating with 8,
The land portion 64 then closes the hydraulic source port 77 between the hydraulic pressure source 11 and the cylinder rear chamber 22 (FIG. 13), and finally the land portion 62 closes the other hydraulic pressure source port 77 that communicates the cylinder front chamber 21 and the tank 18. At the same time as closing the unload port 74, the bund part 64 opens the hydraulic pressure source port 77 between the hydraulic pressure source 17 and the cylinder front chamber 21, completing the switching (FIG. 14).

Then, the pressure in the cylinder front chamber 21 becomes high due to the port 72, so the piston 12 enters the return stroke, and the liquid in the cylinder rear chamber 22 is discharged into the tank through the ports 73, 76.

When the piston retreats to the position shown in FIG. 15, the cylinder front chamber 21 is unloaded by the port 78, so the pressure in the cylinder front chamber 21 is released, and when the pilot pressure from the oscillator 14 is applied to the pilot royal chamber 68, the spool 6
6 starts moving to the left in the figure.

The opening/closing order of each port during this spool movement is the reverse of the opening and closing order of the ports at the start of the return stroke.
4 (Fig. 15), the land portion 64 closes the hydraulic pressure source port 77 to stop high pressure supply to the cylinder front chamber 21 (Fig. 16), and finally the land portion 63 closes the hydraulic pressure source port 77 to stop the high pressure supply to the cylinder front chamber 21 (Fig. 16). At the same time, the land portion 64 connects to the port 7γ.
and 73 are communicated to complete the switching (FIG. 17).

Then, high pressure from the hydraulic pressure source 17 is supplied to the cylinder rear chamber 22, and the piston 12 enters the striking stroke.

At this time, the liquid in the cylinder front chamber 21 is discharged into the tank 18 through two flow paths via ports 71 and 74 and ports γ2 and 75.

By repeating the above steps, the piston hits the drill continuously.

As described above, since the spool valve of the present invention has an auxiliary flow path for reducing back pressure during the piston impact stroke, the back pressure during the impact stroke can be effectively suppressed. Compared to other spool valves, this valve is smaller and lighter, and has the advantage of being able to withstand a high number of blows because the spool is light.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a rotary impact drill equipped with a differential cylinder and a separately excited hydraulic impact machine according to an embodiment of the present invention;
The figure is a partially enlarged cross-sectional view of the impact machine of the same embodiment (state at the start of the piston return stroke), Figures 3 and 4 are explanatory diagrams of spool operation showing the action of the same embodiment, and Figure 5 shows the action of the same embodiment. Second
A partial enlarged sectional view of the impact machine similar to the figure (state at the start of the piston impact stroke), Figures 6 and 1 are explanatory views of the spool operation showing the action of the same embodiment, and Figure 8 is a second embodiment of the present invention. A sectional view showing a rotary impact drill equipped with a differential cylinder and a self-oscillating hydraulic impact machine. Fig. 9 is an enlarged sectional view of a portion of the impact machine of the second embodiment (state at the start of the piston return stroke); Fig. 10 9 is a partially enlarged sectional view of the impact machine (state at the start of the piston impact stroke) showing the operation of the second embodiment, and FIG. 12 is an enlarged partial sectional view of the impactor of the third implementation row (state of piston return stroke start), and FIGS. 13 and 14 are views of the third row A spool operation explanatory diagram showing the action of the implementation row, FIG.
An enlarged partial cross-sectional view of the impact machine similar to Fig. 12 showing the action of (
FIGS. 16 and 17 are explanatory views of the spool operation showing the operation of the third embodiment. 2... Drill impact mechanism section, 3... Drill, 11...
・Differential (double acting) cylinder, 12... Drill impact piston, 13... Spool valve, 21... Cylinder front chamber,
22... Cylinder rear chamber, 24, 25, 26... Land portion, 27... Spool, 39, 40... Cylinder front chamber port, 41... Liquid pressure source port, 42, 43...
・Unload port, 61... Spool valve, 62, 6
3,64°65...land part, 66...spool,
71.72...Cylinder front chamber port, γ3...Cylinder rear chamber port, 74.75, 76...Unload port, 77...Liquid pressure source port.

Claims (1)

[Claims] 1. In a spool valve of a hydraulic impact machine, a plurality of ports and an unload port leading to the double-acting cylinder front chamber of a drilling tool impact piston are provided, and a land portion for switching the ports is provided on the spool. A switching spool valve for reciprocating piston of a hydraulic impact machine, characterized by the following: 2. Switching for reciprocating piston movement of a hydraulic impact machine according to claim 1, wherein both the hydraulic pressure source port communicating with the cylinder front chamber or the cylinder rear chamber and the unloading port are underlapping at the time of switching. spool valve.