JPS6155482A - Differential pressure driven three way type valve - Google Patents

Abstract

PURPOSE:To present a compact three way type valve selectively operated by the difference of a signal pressure for the reference pressure, by constituting a differential pressure detecting mechanism equipping two diaphragms for dividing the inside of a chamber, providing an adjusting screw shaft having a valve, into three parts in a direction of the adjusting screw shaft. CONSTITUTION:A valve case 62, resectively forming in its inner upper part the first chamber 63 and in the central path the decond chamber 65 communicating with he first chamber 63 through a communication hole 64, while provides in the bottom part a three way type valve 66. The first chamber 63 arranges a pressure setting screw shaft 71 appearing in the center part while provides two diaphragms 75, 76, dividing the inside of the chamber 63 int three chambers 72-74, in two parts on the half way in th vertical direction. The diaphargm 76 secures a valve seat 81, which can be seated by a valve 77 provided in said screw shaft 71, and the both diaphragms 75, 76 are constituted as a differential pressure detecting mechanism 111. The second chamber 65, providing a diaphragm 93 dividing the chamber 65 into two chambers 91, 92 and mounting a driving bar 95 to this diapharagm 93, constituted a driving mechanism 112 of the three way type valve 66.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a differential pressure driven three-way valve. For more details,
The present invention relates to a differential pressure driven three-way valve that compares a signal pressure with a reference pressure and switches the three-way valve to operate when the signal pressure decreases by a predetermined value with respect to the reference pressure.

[1SOL technology and its problems] For example, in a three-dimensional measuring machine, the Z axis that holds the probe etc. is slidably guided to the main body stationary part 11, and
The weight of the Z-axis is balanced by air, and the J11 constantor and the like are moved with a relatively light force.

Such an air balance device has a problem in that when the supply air pressure fluctuates or is lost, the Z-axis including the probe falls, damaging the measuring device and the object to be measured.

Therefore, as a countermeasure against this problem, a method has conventionally been adopted in which, for example, a stop of the compressor is detected and an electromagnetic booster is activated accordingly. Another possible way of thinking is to use a pressure detector to detect the pressure inside the cylinder of the air balance device, and to operate the electromagnetic brake based on a detection signal from the pressure detector.

However, in either method, an electric control circuit must be provided separately from the air circuit of the air balance device, which has the drawback of not only being troublesome to handle but also complicating the structure.

For this reason, it is desired to develop a valve that detects the pressure inside the cylinder and switches when the pressure decreases by a predetermined value with respect to the reference pressure, and that is compact overall.

[Object of the Invention] An object of the present invention is to provide a differential pressure driven three-way valve that meets such demands.

[Means and actions to solve the problem] Therefore,
The present invention includes first and second diaphragms for dividing a chamber into three sections in the direction of the adjustment screw shaft, in which the adjustment screw shaft is rotatable but not displaceable in the axial direction, and has a valve; A threaded bushing, a piece fitted to the threaded bushing so as to be displaceable in the axial direction and attached to the first diaphragm, and a piece attached to the second diaphragm and closed by the valve of the adjusting screw shaft. A differential pressure detection mechanism is constructed of a valve seat having a through hole, and a first spring that is interposed between the valve seat and the piece and biases the valve seat and the piece in a direction to separate them from each other. a third diaphragm partitioning a sealed space communicating with the lowest compartment of the detection mechanism; a drive rod attached to the third diaphragm and movable in the axial direction; A drive mechanism consisting of a second spring and a first spring;
and a three-way valve that is switched by displacement of the drive rod of the drive mechanism in the axial direction, and a reference pressure supplied to the first compartment of the differential pressure detection mechanism and a signal pressure supplied to the lowest compartment of the differential pressure detection mechanism. The present invention is characterized in that the drive rod is configured to be displaced to one of two positions by a pressure difference between the two positions.

[Example] FIG. 1 shows a differential pressure driven three-way valve of this example. In the figure, inside a valve box 62, a first chamber 63 is formed in its upper part, and a second chamber 65, which communicates with the first chamber 63 through a communication hole 64, is formed in its center. At the same time, a three-way valve 66 is provided at the bottom.

In the first chamber 63, a pressure setting screw shaft 71 as an adjusting screw shaft supported on the upper surface of the valve box 62 so as to be rotatable but not displaceable in the axial direction is exposed at the center thereof. , there are two first chambers in the middle in the vertical direction that divide the first chamber 63 into three chambers 72, 73, and 74. A second diaphragm 75,76 is provided. The pressure setting screw shaft 71 is provided with a spherical valve 77 at its tip, and a screw bush 7 whose rotation is restricted by a rotation stopper 78 and which is movable in the axial direction of the pressure setting screw shaft 71.
9 are screwed together. The screw bush 79 has the first
A piece 80 fixed to the center of the diaphragm 75 is fitted so as to be displaceable in the axial direction. On the other hand, a valve seat 81 is fixed to the center of the second diaphragm 76 . A through hole 82, which is closed by the valve 77, is formed in the center of the valve seat 81 and extends through the upper and lower surfaces thereof.

Further, between the upper surface of the valve seat 81 and the lower surface of the piece 80, a spring 83 is provided between the lower surface of the valve seat 81 and the bottom wall of the first chamber 63. Valve seat 81
A spring 84 is interposed in each case to bias the two upwards. Note that the biasing force exerted by the spring 84 is sufficiently smaller than the biasing force exerted by the spring 83. Furthermore, each chamber 7
A supply hole 85 for introducing reference air pressure into each chamber 72 is provided on the peripheral wall of No. 2, an atmospheric CH discharge hole 86 is provided on the peripheral wall of each chamber 73, and a signal air pressure is introduced into each chamber 74 on the peripheral wall of each chamber 74. Supply holes 87 are drilled in each case. Here, a first chamber 63 having the pressure setting screw shaft 71, a first chamber 63 having the pressure setting screw shaft 71; Second diaphragm 75,76, screw bushing 79
．． A bridge 80, a valve seat 81 having a through hole 82, and a spring 83
Thus, the differential pressure detection mechanism lll of this embodiment is configured.

Further, the second chamber 65 is provided with a third diaphragm 93 that partitions the chamber 65 into upper and lower chambers 91 and 92. Each of the upper chambers 91 is formed in a closed space that communicates with each of the chambers 74 through the communication hole 64 .

Further, an atmosphere opening hole 94 is bored in the peripheral wall of each chamber 92. Further, the diaphragm 93 has a drive rod 95 provided at the center of the valve box 62 so as to be movable in the axial direction.
The upper end of the is integrally attached. The drive rod 95 is urged toward each chamber 74 by a spring 96. Here, each chamber 91, the third diaphragm 93,
The drive rod 95 and the spring 96 constitute the drive mechanism 112 of this embodiment.

Further, the three-way valve 66 includes an input port 101, an output port 102, and an atmosphere opening port 10 formed on the peripheral wall of the valve box 62.
3, a valve seat 105 formed in the middle of a flow path 104 that communicates these with each other, and a spring 106 that allows the valve seat 10 to
The valve 107 is biased in a direction to close the valve 5 and is displaced by the drive rod 95 in a direction opposite to the direction in which the spring 106 is biased. An operating air pressure supply source is connected to the input port lot, and a control device that is switched and activated when the signal air pressure decreases by a predetermined value with respect to the reference air pressure is connected to the output port 102, respectively. . Here, when the valve 107 is in the state shown in FIG. 1, the input port 101 and the output port 102 are communicated with each other. Then,
Operating air pressure is supplied to the control equipment through an input port 101 and an output port 102. On the other hand, the valve 107 is
5 is closed, the input port 101 is closed and the output port 102 is communicated with the atmosphere opening port 103.

Then, the air inside the control device is discharged to the atmosphere through the output 1102 and the atmosphere opening 103.

Next, an example of how to use the differential pressure driven three-way valve 61 will be explained. For example, when applied to a fall prevention device for a Z-axis (spindle with n-electrons, etc. attached) that has an air balance device of a coordinate measuring machine, as shown in Fig. 2, the input port 1
01 and the supply hole 85 are connected to the air supply circuit 30. Also, a control device for connecting the supply hole 87 to the cylinder 9 of the air balance device 17 and integrally locking the output 0102 to the spindle 13 to the member side;
Here, the spindle 13 is connected to a cylinder device 53 which is designed in such a way that it locks integrally with the component side 1 when the supply pressure is cut off.

The air balance device 17 includes a cylinder 1 housed in a spindle 13 that is slidably provided in the vertical direction.
9, a piston 21 slidably housed within the cylinder 19, and a piston rod 22 whose lower end is connected to the piston 21 and whose -L end is held by a stationary member or the like.

Note that a holder 16 is provided at the lower end of the spindle 13 for attaching a probe or the like.

Further, the air supply circuit 30 includes a high-pressure air pressure source 31
Constant air pressure supplied from, for example, 5Kg・f/cr
f air is supplied to an air regulator 34 through an air filter 32 and a micro mist separator 33. The air regulator 34 has a secondary side connected to the flow rate regulating pressure reducing valve 35 and the input port 101 of the differential pressure driven three-way valve 61, respectively, and maintains the pressure on the secondary side at a set pressure, for example, 4 kg*f/cm''. The flow rate adjustment pressure reducing valve 35 has a secondary side connected to the cylinder 19.
It is connected to the supply hole 87 of the internal and differential pressure driven three-way valve 61, respectively, and the pressure on the secondary side, that is, the pressure inside the cylinder 19, is maintained at a set pressure, for example, 2 Kg-f/crn'.

In use, first adjust the flow rate adjustment pressure reducing valve 35,
The secondary side pressure of the flow rate adjustment pressure reducing valve 35 is adjusted to the spindle 13.
Set the pressure to match the weight of the moving parts. Now, if the total weight of the movable parts of the spindle 13 is M [Kg・f] and the inner diameter (diameter) of the cylinder 19 is D [II], then the pressure P inside the cylinder 19 is P = 4 M/ πD 2 [ Kg11f/c rn'
].

Therefore, the pressure on the secondary side of the flow rate adjustment pressure reducing valve 35 is set to pressure P. Thereby, the secondary side pressure P of the flow rate adjustment pressure reducing valve 35 is supplied into the cylinder 19 and is also supplied to each chamber 72 through the supply port 85 of the differential pressure driven three-way valve 61. On the other hand, the pressure within the cylinder 19 is applied as a signal pressure to each chamber 74 through the supply port 87 of the differential pressure driven three-way valve 61.

Here, if the pressure setting screw shaft 71 of the differential pressure driven three-way valve 61 is rotated in advance and the compression force of the spring 83 is set to be balanced with the signal pressure in each chamber 74, the second The lower surface of the diaphragm 76 has a force due to the signal pressure and the repulsive force of the spring 84 (this is a preload to prevent the signal pressure from decreasing below the set pressure due to minute fluctuations in the signal pressure). As a result of the repulsive force 83 acting, the second diaphragm 76 is pushed upward in FIG. Then, as the second diaphragm 76 is pushed up, the through hole 82 is closed by the valve 77, and as a result, the signal pressure in each chamber 74 enters each chamber 91 through the communication hole 64, causing the third diaphragm 93 to close as shown in FIG. Press down in the middle. third diaphragm 9
3 is pressed down, the valve 107 is activated via the drive rod 95.
is released from the valve seat 105 against the spring 106,
The input port lot and the output port 102 are communicated.

Thereby, when the secondary side pressure of the regulator 34 is supplied to the cylinder device 53, the spindle 13 becomes in a state where it can move up and down in the vertical direction.

Measurement is performed in this state. During measurement, the lower end of the spindle 13 is held in the hand and the measuring element is moved in three-dimensional directions and successively brought into contact with the object to be measured. Then, the positions in the x-, y-, and z-axis directions where the contact point or the like contacts the object to be measured are detected by detectors (not shown) and then displayed on a display or the like.

At the time of this measurement, when various types of probes etc. are attached to the holder 16 for each measurement item, the total weight changes depending on the probes etc. 5, so the pressure inside the cylinder 19 is changed according to the total weight. There is a need. Therefore, the flow rate adjustment pressure reducing valve 3
5 is set to a pressure commensurate with the total weight, and the secondary pressure is supplied to the cylinder 19 to maintain balance.
also supplied.

At this time, although the screw bushing 79 is fixed, each chamber 7
Since the air pressure supplied into the bridge 2 acts on the bridge 80 via the first diaphragm 75, the spring 83 is compressed in accordance with the displacement of the bridge 80. Therefore, even if the total weight changes due to the measuring tip etc. attached to the holder 16 and the secondary side pressure of the meteor adjustment pressure reducing valve 35 is changed according to the total weight, the spring will change depending on the secondary side pressure. Since the compressive force of 83 changes, similarly to the above, when the signal pressure is higher than the set pressure, the input port lO1 and the output port 102 remain in communication with each other.

If the signal pressure drops below the set pressure due to some reason, such as a leak in the air piping, the second diaphragm 76 is pushed down. Then, the through hole 82 of the valve seat 81
is released from the valve 77, the air in each chamber 74 enters each chamber 73 through the through hole 82 and is exhausted from the atmosphere opening hole 86. Therefore, as a result of the driving rod 95 being pushed up by the spring 96, the valve 107 interrupts the circuit that has been connected until now by the spring 106, and the output port 102 and the atmosphere opening port 1 are connected to each other.
03.

As a result, the secondary side pressure of the regulator 34 is no longer supplied to the cylinder device 53, and the cylinder device 5
3 is released to the atmosphere. As a result, the spindle 13 is integrally locked to the stationary member and is prevented from falling.

Therefore, according to the differential pressure driven three-way valve 61 of this embodiment, when the signal pressure decreases by a predetermined value with respect to the reference pressure by comparing the reference pressure and the signal pressure, the three-way valve 66 switches and operates. Even in the case where the signal pressure changes as the reference pressure changes, it is possible to prevent the signal pressure from decreasing with respect to the reference pressure without adjusting the set pressure of the spring 83 using the pressure setting screw shaft 71 every time the reference pressure changes. Can be detected accurately,
And thereby the three-way valve 66 can be switched into operation.

Further, even when changing the set pressure by the spring 83, fine adjustments can be made by rotating the pressure setting screw shaft 71. In addition, since the reference pressure can be changed using a device other than the pressure setting screw shaft 71, remote control is possible. Furthermore, since these functions are integrated, the overall structure can be made compact.

For example, when a Z-axis (spindle with a measuring head etc. attached) that has an air balance device of a two-dimensional measuring machine falls,
If applied to the device, a flow rate regulating pressure reducing valve 35 that sets the pressure in the cylinder 19 to a pressure commensurate with the weight of the spindle 13.
The pressure immediately after the output from the secondary side is compared with the pressure inside the cylinder 19, and when the pressure inside the cylinder 19 decreases by a predetermined value with respect to the pressure immediately after the output from the secondary side, the cylinder device 53 of the fall prevention device is released. Therefore, even if the air pressure source side changes temporarily, the cylinder device 53 will not be released, so there will be no interruption of measurement work due to this.

In addition, due to the replacement of the measuring head etc., the weight of the movable part of the spindle 13 changes, and the flow rate adjustment pressure reducing valve 35 changes depending on the weight.
When the secondary side pressure of Since there is no need to finely adjust the pressure setting screw shaft 71 that adjusts the pressure, it is only necessary to adjust the pressure reducing valve 35.
Therefore, adjustment is easy.

In addition, in the embodiment mentioned above, as an example of use, a case was described in which it was applied to a device when a Z-axis (spindle to which a probe, etc. is attached) of a coordinate measuring machine is dropped. The present invention is.

The present invention is not limited to this example, and can be widely applied as a valve that operates a control device or the like based on the difference in signal pressure with respect to a reference pressure.

[Effects of the Invention] As described below, according to the present invention, it is possible to provide a differential pressure-driven three-way valve that is compact and that switches and operates based on the difference in signal pressure with respect to the reference pressure.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the internal structure of an embodiment of the present invention, and FIG. 2 is a system diagram of the system in use. 63... First chamber, 66... Three-way valve, 71... Pressure setting screw shaft as adjustment screw shaft, 75... First diaphragm, 76... Second diaphragm, 93...・
・Third diaphragm, 79...Screw bushing, 80
... Piece, 81... Valve seat, 82... Through hole, 83.
...Spring, 93...Diaphragm, 96...Spring,
91... Each chamber, 95... Drive rod, 111... Differential pressure detection mechanism, 112... Drive mechanism.

Claims (2)

[Claims] (1) First and second diaphragms for dividing a chamber into three sections in the direction of the adjustment screw shaft, in which the adjustment screw shaft is rotatable but not displaceable in the axial direction and has a valve; a piece fitted to the threaded bush so as to be displaceable in the axial direction and attached to the first diaphragm; and a piece attached to the second diaphragm and closed by the valve of the adjusting screw shaft. A differential pressure detection mechanism comprising: a valve seat having a through hole; and a first spring interposed between the valve seat and the piece and biasing the valve seat and the piece in a direction to separate them from each other; a third diaphragm that partitions a sealed space communicating with the lowest compartment of the mechanism; a drive rod attached to the third diaphragm and movable in the axial direction; and a drive rod that moves the drive rod toward the lowest compartment. and a three-way valve that is switched by displacement of the drive rod of the drive mechanism in the axial direction, and is supplied to the uppermost compartment of the differential pressure detection mechanism. A differential pressure driven three-way valve, characterized in that the drive rod is configured to be displaced to one of two positions by a pressure difference between a reference pressure and a signal pressure supplied to the lowest compartment. (2) In claim 1, a second spring biases the valve seat in a direction opposite to the biasing force of the first spring and with a force weaker than the biasing force of the first spring. A differential pressure driven three-way valve characterized by being equipped with a spring.