JPS5815709Y2 - switching valve - Google Patents

Description

[Detailed Description of the Invention] Field of Application The present invention relates to an air-saving switching valve used to control a double-acting cylinder using compressed air as a working medium.

Prior art and its problems Generally, when cylinder control is performed using a two-position switching valve, compressed air from an air source is transferred to the cylinder C by switching the flow path using the switching valve a, as shown in Fig. 1A. However, the compressed air filled in the cylinder C and the pipe d is discharged to the atmosphere during each stroke, which is very uneconomical.

Therefore, in order to reuse the compressed air, a structure as shown in Fig. 1B using a three-position switching valve was developed in JP-A-51-6.
It is known from the publication No. 5286.

This consists of an air source e, a 3-position switching valve f, a cylinder g, and piping that connects them.The switching valve f switches the flow path to transfer compressed air from the air source e to the working chamber tx of the cylinder g.
By pressing the switch valve f to the intermediate switching position, both working chambers i, j'? I'm trying to communicate.

However, if you press the 6 button to switch the switching valve after the pressures of both working chambers x+j are balanced at the intermediate switching position, there is no means for detecting the pressure balance. It is necessary to carry out drive control, which has the disadvantage of causing loss time.

Technical Problems of the Present Invention The present invention detects the balance state of air pressure due to the communication between the two working chambers at the intermediate switching position of the switching valve, and automatically moves the spool from the intermediate switching position to the other position according to the balanced state. The object is to make the switching position one drive.

Technical Means The technical means taken to solve the above problem is to form a working chamber in its entirety between the seal lands at both ends of the spool and the piston for driving the spool 1, which is disposed opposite to the seal lands at both ends of the spool, and to A pilot chamber into which pilot fluid pressure is introduced is provided on the outer surface side of the piston, and the piston is configured to press the spool at an intermediate switching position 1 by driving by the pilot fluid pressure; The supply hole is connected to the cylinder ports located on opposite sides of each other through separate communication passages, and when the switching land of the spool is in the intermediate switching position where it is located above the cylinder port and blocks each port, both cylinders are connected. A control hole is provided to allow the port and both action chambers to communicate with each other.

action The above technical means works as follows.

That is, when the spool at one switching position is driven through the piston to the intermediate switching position 1, both cylinder ports and both working chambers are all communicated through the control hole provided in the switching land, and the fluid pressure in each working chamber is We move toward mutually increasing prices.

At this time, in both action chambers, the bias force is generated based on the difference in the amount of compression of the springs, and the spring pressed by the piston on the drive side is stronger than the spring on the opposite side. It is compressed a lot and holds a large biasing force.

Therefore, the resultant force of the urging force of the spring on the first drive side and the acting force due to the fluid pressure flowing into the action chamber is the resultant force of the urging force of the spring and the acting force due to the fluid pressure flowing into the action chamber on the opposite side. When the force is exceeded, the spool automatically moves from the intermediate switching position towards the other switching position.

With this movement, the communication between both cylinder ports and both working chambers through the control hole is cut off, and the cylinder port and working chamber, which were on the high pressure side in 1. The cylinder port and the working chamber communicate with the supply port, and the pressure difference in both working chambers causes the spool to be driven once in the final switching position 1.

Unique effects caused by this invention The present invention produces the following unique effects.

That is, by simply driving the spool with the piston in the intermediate switching position 1, the spool can then be automatically switched at the final switching position 1 after the required time, and therefore the stroke of the piston can be reduced to a very small value between the spools. Can be set.

Sweet, the consumption of pilot fluid for driving the piston is small.

An embodiment of the present invention will be described below with reference to the drawings.

2 to 5, 1 is a valve body, which has a compressed air supply port 1-2, a cylinder port 3゜4, and an exhaust port 5.6'', inside the valve body 1. A spool 9 is fitted into the valve chamber 7 formed through the sleeve 8 so as to be slidable left and right.

The sleeve 8 is provided with a supply hole 10, a cylinder hole 1L12, and an exhaust hole 13.14 that communicate each port of the valve body 1 with the valve chamber 7, and the spool 9 is provided with a valve provided at both ends thereof. Between the seal lands 17.18 for sealing the chamber 7, there is a switching land 15.16 which crosses over the cylinder passage hole 11.12 and forms a flow path switching section by cooperating with the cylinder passage hole. and the switching land 15°1
6, both control holes 19.2 are drilled in the control hole 19.20'.
0 are communicated with each other through the communication hole 21, thereby,
The switching lands 15 and 16 have two cylinder through holes LL1
Intermediate switching position (third position) located above 2 and blocking each port
(Fig.), these control holes 19 and 20 communicate with both cylinder through holes 11 and 12.

Further, both ends of the valve body 1 are provided with an angle greater than the spool which abuts the end of the spool 9 and performs the switching movement.
Spring 24, 25-e is interposed between the large-diameter piston 22, 23't and the spool 9 to form the piston chamber 26.
．． an action chamber 28, which is slidably disposed within the piston 27 and defined between the back surface of the piston 22, 23 and the spool 9;
29 are in communication with the cylinder passage holes 12.11 through communication passages 31.30, respectively, and the piston 22.2
In pilot chambers 32 and 33 defined on the front surface of 3, pilot fluid supply and discharge ports 34 and 35 from pilot valves 36 and 37 are opened.

In the figure, 38 is the cylinder, 39.40 is the cylinder chamber, 41 is the cylinder piston, 42 is the air supply source, 43a and 43b are the switching valve and the cylinder 38.
It shows the piping that connects the

In Figure 2, both pilot valves 36 and 37 are turned off,
Moreover, the spool 9 is shown moving to the left and maintaining the first switching position, and at this time the compressed air from the supply source 42 is
The action chamber 29 is filled from the supply port 2 through the supply passage hole 10, the valve chamber 7, the cylinder passage hole 11, and the communication passage 30, where it exerts an action force on the piston 23 and the spool 9, and the piston 23'1f : Pressing the spool 9 to the right end position in the piston chamber 27 and holding the spool 9 in the illustrated switching position where its end abuts the piston 22 against the biasing force of the spring 24 on the opposite side, and at the same time, the compressed air is flows from the cylinder passage hole 11 through the cylinder port 3 into the cylinder chamber 39 of the cylinder 38, where the cylinder piston 4
-1 is pushed out to the position shown.

At this time, the other working chamber 28 passes through the communication path 31,
Further, the cylinder chambers 40 each communicate with the cylinder passage holes 12 via the cylinder ports 4, and from there communicate with the valve chamber 7, the exhaust passage hole 14, and the exhaust port 6, and are open to the atmosphere.

1. When the pilot valve 36 operates and pilot fluid is supplied to the pilot chamber 32, since the piston 22 has a larger diameter than the spool 9, the force exerted by the pilot fluid on the piston 22 is transferred into the action chamber 29. When the button is pressed, the force of the air pressure acting on the right end of the spool 9 is overcome, and the piston 22 immediately moves to the position 1 where it abuts against the stopper portion 44, and the spool 9 is moved so that the switching lands 15 and 16 move through the cylinder as shown in FIG. In intermediate switching position 1, located above hole 11.12, rightward movement is performed.

In this state, the communication between the supply port 2 and the cylinder port 3 and between the cylinder port 4 and the exhaust port 6 is cut off, and the control hole 19.20 is placed above the cylinder passage hole 11.12. Open cylinder ports 3 and 4
As a result, the high pressure condensed air filling the cylinder chamber 39 and the working chamber 29 of the cylinder 38 flows into the cylinder chamber 40 from the cylinder port 4 and passes through the communication passage 31 to the other working chamber. 28, and due to this reflux, the air pressure in the cylinder chamber 39 and the working chamber 29 gradually decreases, while the air pressure in the cylinder chamber 40 and the working chamber 28 gradually increases, so that they are in equilibrium with each other. In this case, the resultant force of the acting force due to the air pressure in the action chamber 28 and the biasing force of the spring 24 with a large amount of compression becomes the combined force of the acting force due to the air pressure in the action chamber 29 and the urging force of the spring 25 with a small amount of compression. When it is defeated, spool 9 gradually begins to move to the right.

When the rightward movement advances and reaches the position shown in FIG. 4, the communication between the control hole 20 and the cylinder passage hole 12 is cut off, and the switching land 16 passes over the cylinder passage hole 12 to close the cylinder. Since the port 4 starts communicating with the supply port 2, high-pressure compressed air from the air source 42 starts to flow into the cylinder chamber 40-\ and also flows into the action chamber 28 via the communication path 31, while switching Since the land 15 passes over the cylinder passage hole 11 and starts communication between the cylinder port 3 and the exhaust port 5, the remaining air in the cylinder chamber 39 and the working chamber 29 is discharged from the exhaust port 5 to the atmosphere. The acting forces of the compressed air in the action chambers 28 and 29 at both ends of the spool 9 become significantly unbalanced, and the difference in acting forces takes over the rightward action of the spring 24 in the previous step 1 and causes the spool 9 to move rightward at once. Let it reach the second switching position shown in FIG.

In this switching position, the right end of the spool 9 comes into contact with the piston 23, and the supply passage hole 10 and the cylinder passage hole 12 and between the cylinder passage hole 11 and the exhaust passage hole 13 are in a fully open communication state, so that the cylinder piston 41 assumes the retracted position shown, and when it reaches the second switching position shown in FIG.
Return the pilot valve 36 again and open the pilot chamber 32.
Even if the pilot fluid inside is discharged, one of the working chambers 29 is already at atmospheric pressure and the other working chamber 28 is filled with high-pressure compressed air, so the spool 9 will not move due to the working force applied to the compartment. This second switching position is maintained.

When the pilot valve 37 is operated, the operation is opposite to that when the pilot valve 36 is operated.

FIG. 6 shows a different embodiment of the invention, which shows the valve body 1
Stoppers 45° 46 for the spool 9 are provided on both sides of the spool 9, thereby allowing the spool 9 and the piston 22 to be placed in the switching position.
．． 23, and the amount of expansion and contraction of the springs 24 and 25 can be increased compared to the previous embodiment.
A feature of this method is that it facilitates design consideration when moving from an intermediate switching position in the middle of switching to the next process (FIGS. 3 to 4).

The switching valve having the above configuration automatically switches the valve from the first to the second or vice versa via an intermediate switching position (Fig. 3) where both cylinder ports communicate. The way the signal is given) is the same as that of a conventional two-position switching valve, but the compressed air on the side to be exhausted is recirculated to the side to be supplied to the intermediate switching position, which corresponds to the neutral position of the three-position switching valve. Since it is reused, only the volume whose pressure has decreased due to pressure equalization is exhausted, and the amount of air consumed can be significantly reduced compared to the conventional high pressure system in which the entire volume is exhausted.

Therefore, for example, when the internal volume of the cylinder 38 and the pipes 43a and 43b in FIG. Comparing A with the air consumption amount A in the conventional case with similar values, in the case of the present invention, the air consumption amount differs depending on the load condition of the cylinder.
Calculating for each case shows that if the cylinder piston does not move back and forth just by equalizing the pressure in both cylinder chambers, then A = 0.697, and conversely, by equalizing the pressure in both cylinder chambers, Therefore, if the cylinder piston moves both back and forth, A//Ao = 0,
455, and if the cylinder piston eventually moves only in one direction due to pressure equalization, A/A □ = 0.57
Therefore, it can be seen that compressed air can be saved by a minimum of 30% and a maximum of 54%.

[Brief explanation of drawings]

Figures 1A and B are explanatory diagrams of conventional cylinder control circuits;
5 to 5 are cross-sectional views showing an embodiment of the present invention in different switching states, and FIG. 6 is a partially omitted cross-sectional view showing a different embodiment of the present invention. 2... Supply port, 3, 4... Cylinder port, 5
゜6...Exhaust port, 9...Spool, 15.16
...Switching land, 19.20...Control hole, 22.2
3...Zeston, 24.25...Sufring, 28,
29...action chamber.

Claims (1)

[Scope of utility model registration request] Two cylinder ports that are switched and connected to the supply port by the switching land as the spool slides, and two exhaust ports that are connected to the other cylinder port when one cylinder port is connected to the supply port. In a switching valve equipped with a port, an action chamber is defined between the seal lands at both ends of the spool and a piston for driving the spool, which is placed opposite to the seal lands via a spring, and pilot fluid pressure is introduced to the outer surface of the piston. The piston is configured to push the spool at an intermediate switching position 1 by being driven by pilot fluid pressure, and the action chamber is connected to cylinder ports located on opposite sides of the supply port. and a control that causes both cylinder ports and both working chambers to communicate with each other when the switching land of the spool is located on the cylinder port and is in an intermediate switching position of blocking each port. A switching valve with a hole.