Patent Description:
In machining, cutting powder or chip powder of metal produced during cutting process adheres to surfaces of workpieces. In order to remove such powder and clean the surfaces of the workpieces, blasting compressed fluid (mainly compressed air) is widely performed. Compressed-fluid discharge control devices used for performing such blasting (blowing) include, for example, gun-shaped tools disclosed in <CIT> and <CIT>. Gun-shaped compressed-fluid discharge control devices of this type, which are often called "air blow guns", "fluid blow guns", or "discharge guns", are expressed as "air blow guns" in the description below.

This type of air blow gun includes a housing including a handle gripped by an operator and a lever rotatably attached to the housing. When the operator pushes the lever toward the handle using their fingers, an opening and closing valve disposed between a supply channel and a discharge channel formed inside the handle opens, and thereby the supply channel and the discharge channel communicate with each other. This causes compressed air supplied from a compressed-air supply source to the supply channel to flow into the discharge channel and then to be discharged from an opening (discharge port) in the discharge channel.

<CIT> discloses a pilot-operated control valve assembly comprising a suction tude and an outlet pipe connected by a valve pocket in which a diaphragm valve comprising a damping hole is located. The diaphragm valve separates the valve pocket into a first cavity and a second cavity, wherein the diaphragm valve blocks communication between the suction tude and the outlet pipe under active force of an elastic element. A solenoid valve opens a pilot path when energized, thus leading to the diaphragm valve permitting communication between the suction tude and the outlet pipe.

<CIT> discloses an electromagnetic pilot-type valve comprising a housing with an inlet and an outlet, wherein communication between inlet and outlet can be controlled by a diaphragm assembly. The diaphragm assembly is forced towards a seat by a spring. Further, a pilot path that communicates the valve chamber with the outlet can be controlled by means of a solenoid valve.

<CIT> discloses an electromagnetic pilot-type valve with a valve body comprising an inlet and an outlet, wherein communication between inlet and outlet is controlled by a diaphragm valve that is forced towards a valve seat by a spring. The communication of a pilot path, spanning from one side of the valve chamber to the outlet, is controlled by means of a solenoid valve.

As described above, the operator needs to grip the lever to perform blast of air using the air blow gun. That is, the operator needs to operate the air blow gun at a worksite where blast of air is performed. Thus, in a case where the operator needs to operate the air blow gun in a place where, for example, water sprays all over, the operator disadvantageously gets wet.

A principal object of the present invention is to provide a compressed-fluid discharge control device capable of being opened and closed electrically without manual opening and closing operation directly performed by an operator.

Another object of the present invention is to provide a compressed-fluid discharge control device also capable of being opened and closed remotely.

This problem is solved by the compressed-fluid discharge control device according to claim <NUM>. Preferred embodiments of the invention are evident from the dependent claims.

In the present invention, a solenoid valve is used as the pilot-chamber opening and closing valve for opening and closing the pilot chamber to open and close the diaphragm valve. The diaphragm valve can be opened by energizing the solenoid valve to open the pilot chamber and can be closed by de-energizing the solenoid valve to close the pilot chamber. That is, an operator does not need to perform opening and closing operation at a worksite. Thus, even in a case where water sprays all over the worksite, the operator is prevented from getting wet.

Moreover, this structure enables a control switch for opening and closing the solenoid valve to be disposed in a place away from the solenoid valve. In this case, the solenoid valve and the diaphragm valve can be opened and closed remotely, thereby preventing the operator from getting wet by water spray and the like more reliably.

In addition, in this structure, compressed fluid that has reached a valve chamber flows into the discharge channel all at once and is discharged from an open end (discharge port) of the discharge channel. Thus, an instantaneous high discharge pressure (peak pressure) can be obtained immediately after the start of discharge. Such instantaneous discharge of compressed fluid at a high discharge pressure can easily bring, for example, objects at rest into a state of motion. This improves the efficiency in removing chips, dust, and other particles. Moreover, the peak pressure can be obtained without discharging a large amount of compressed fluid. This results in a reduction in the consumption of compressed fluid and thus leads to energy savings.

According to the invention a storage chamber configured to store compressed fluid be disposed between the supply channel and the valve chamber. In this case, compressed fluid that has been stored in the storage chamber in advance flows into the discharge channel all at once as the diaphragm valve opens. As a result, even higher discharge pressure can be easily obtained. As a matter of course, the efficiency in removing the chips, dust, and other particles is further improved in this case.

The storage chamber may be configured as a variable-volume inner chamber of which volume can be changed. This enables the upper limit of the discharge pressure (peak pressure) of compressed fluid to be set according to the uses of the device.

It is preferable that a regulating valve configured to adjust the flow rate of compressed fluid introduced from the supply channel into the storage chamber be provided. In this case, for example, the flow rate of the compressed fluid introduced into the storage chamber can be set small by reducing the opening degree of the regulating valve. In a case where the diaphragm valve is still open after the discharge at the high discharge pressure ends, compressed fluid passes through the storage chamber, reaches the discharge channel, and is discharged at a low pressure. That is, blowing at a low pressure can be continued.

In general, kinetic frictional force that acts on an object in motion is smaller than static frictional force that acts on an object at rest. Consequently, once chips and dust are subjected to a high discharge pressure and brought into a state of motion, the chips and dust can be maintained in the state of motion even with a low discharge pressure. As a result, removal of such foreign substances can be continued.

Furthermore, it is preferable that the pilot-chamber opening and closing valve be configured to establish and block communication between the pilot chamber and the discharge channel. In this case, when the pilot chamber is opened, the compressed fluid inside the pilot chamber flows into the discharge channel. That is, the compressed fluid inside the pilot chamber can also be discharged and used to remove the dust and the like. This results in a further increase in the peak pressure immediately after the start of discharge and, in addition, leads to more energy savings.

Reducing the stroke of the diaphragm valve further increases the response speed. That is, the peak pressure can be obtained immediately after the operator operates an operating member for opening and closing. To achieve this, it is preferable that a contact member displaceable relative to a valve element of the diaphragm valve be provided to limit the displacement of the valve element by coming into contact with the valve element. That is, a displacement limiting unit may be provided.

In this case, further displacement of the valve element is stopped by the contact of the contact member with the valve element. The opening degree at a point in time when the displacement is stopped is defined as the maximum opening degree of the diaphragm valve. In this manner, the maximum opening degree of the diaphragm valve can be made smaller than the designed maximum opening when the contact member is not brought into contact with the valve element. As a result of this, the flow rate of the pressurized fluid discharged from the diaphragm valve is reduced compared with the designed flow rate. Consequently, pressurized fluid of more than the required amount is prevented from being discharged.

Moreover, the stop position of the valve element can be changed by changing the position of the contact member. That is, the maximum opening degree of the diaphragm valve can be changed to any desired value. The maximum opening degree of the diaphragm valve and thus the flow rate and the peak pressure of the pressurized fluid flowing from the diaphragm valve can be precisely regulated by precisely adjusting the position of the contact member.

The pilot-chamber opening and closing valve (solenoid valve) can also be disposed in a place away from a worksite. To do so, the pilot chamber and the discharge channel may communicate with a valve chamber of the pilot-chamber opening and closing valve via a pipe. The pilot-chamber opening and closing valve can be disposed away from the worksite by the length of the pipe. Consequently, even in a case where water sprays all over the worksite, the pilot-chamber opening and closing valve is prevented from getting wet.

According to the present invention, the solenoid valve configured to be opened when energized and to be closed when de-energized is used as the pilot-chamber opening and closing valve that opens and closes the pilot chamber. This configuration enables the solenoid valve to be opened and closed electrically. That is, the pilot-chamber opening and closing valve can be opened and closed without operator's manual operations performed at the worksite. Consequently, the operator is prevented from getting wet.

In addition, the diaphragm valve is opened and closed as the pilot chamber is opened and closed. When the diaphragm valve is opened, compressed fluid that has reached the valve chamber flows into the discharge channel all at once and is discharged from the discharge port. As a result, regardless of the operating speed of the operating member for opening and closing, an instantaneous high discharge pressure (peak pressure) can be obtained immediately after the start of discharge. Consequently, a high discharge pressure can be obtained without discharging a large amount of compressed fluid. This results in a reduction in the consumption of compressed fluid and thus leads to energy savings.

A large force acts on, for example, objects at rest by instantaneously discharging compressed fluid at a high discharge pressure. As a result, the objects are easily brought into a state of motion. In a case where the objects correspond to, for example, chips and dust, the efficiency in removing such foreign substances is improved.

Preferred embodiments of a compressed-fluid discharge control device according to the present invention will be described in detail below with reference to the accompanying drawings. In the examples below, compressed air is used as compressed fluid. In the below, terms such as "left", "right", "down", and "up" indicate respectively the left side, the right side, the lower side, and the upper side in <FIG> and <FIG>. However, these terms are used for convenience to facilitate understanding and do not limit the position of the compressed-fluid discharge control device in practical use.

<FIG> is a schematic side sectional view of main part of a compressed-fluid discharge control device <NUM> according to a first embodiment. The compressed-fluid discharge control device <NUM> includes a first housing <NUM> including a storage chamber <NUM> as an inner chamber, a second housing <NUM> accommodating a diaphragm valve <NUM>, and a holder <NUM> holding a solenoid valve <NUM> serving as a pilot-chamber opening and closing valve configured to open and close a pilot chamber. The compressed-fluid discharge control device <NUM> is of a so-called stationary type in which the box-shaped first housing <NUM> is positioned and secured in place in a predetermined area at a worksite when the compressed-fluid discharge control device <NUM> is in use.

The first housing <NUM> includes a hollow body portion <NUM> provided with a first supply channel <NUM> formed in a side part of the body portion <NUM>. A regulating valve <NUM> is attached to the first supply channel <NUM>, and an L-shaped pipe fitting <NUM> is connected to the regulating valve <NUM>. The regulating valve <NUM> extends linearly in the longitudinal direction of the first housing <NUM>, and a connecting part of the regulating valve <NUM> faces upward. A connection part of a vertical portion <NUM> constituting the L-shaped pipe fitting <NUM> is connected to the connecting part, while a supply pipe (not illustrated) is connected to a connection part of a horizontal portion <NUM> constituting the L-shaped pipe fitting <NUM>. As a result, in an exterior view thereof, the supply pipe branches off from the regulating valve <NUM>. Compressed air supplied from a compressed-air supply source (not illustrated) flows into the supply pipe.

A flow control path <NUM> including an orifice <NUM> is formed inside the regulating valve <NUM>. A needle <NUM> enters the orifice <NUM> in a retractable (withdrawable) manner. The flow control path <NUM> is closed when the needle <NUM> enters in the orifice <NUM>, and the flow control path <NUM> is open when the needle <NUM> is withdrawn and retracted from the orifice <NUM>.

The body portion <NUM> includes an opening of a hollow interior formed in an upper part thereof. A cover portion <NUM> is disposed in the opening to close the hollow interior, whereby the storage chamber <NUM> is formed. The storage chamber <NUM> and the first supply channel <NUM> communicate with each other as a matter of course. The cover portion <NUM> and the body portion <NUM> are joined to each other by, for example, screws (not illustrated). In this case, the body portion <NUM> can be detached from the cover portion <NUM> by loosening the screws. The volume of the storage chamber <NUM> can be changed by replacing the body portion <NUM> with another body portion that, in cooperation with the cover portion <NUM>, forms a storage chamber <NUM> having a hollow interior of a different volume. The gap between the cover portion <NUM> and the body portion <NUM> is sealed with a first seal member <NUM>.

The cover portion <NUM> includes a communication channel <NUM> formed in a thickness direction thereof. A tubular member <NUM> with a substantially T-shaped cross-section is fitted into the communication channel <NUM>. The tubular member <NUM> has a communicating hole <NUM> with a narrower opening width than the communication channel <NUM>. The gap between the tubular member <NUM> and the cover portion <NUM> is sealed with a second seal member <NUM>.

The second housing <NUM> includes a first holding member <NUM> and a second holding member <NUM> that hold the diaphragm valve <NUM> therebetween. The first holding member <NUM> is provided with a second supply channel <NUM> having an opening facing the communicating hole <NUM> and a valve chamber <NUM> connecting to the second supply channel <NUM> and circularly extending inside the second housing <NUM>. The valve chamber <NUM> communicates with a discharge channel <NUM> extending in the longitudinal direction of the second housing <NUM>. That is, the valve chamber <NUM> is disposed between the second supply channel <NUM> and the discharge channel <NUM> and communicates with both the channels <NUM> and <NUM>. Moreover, the discharge channel <NUM> has an opening facing the valve chamber <NUM>, and the opening is provided with a ring-shaped first seat <NUM> protruding from the opening.

The diaphragm valve <NUM> includes a thick valve element <NUM> having a substantially cylindrical shape and a flange portion <NUM> having a smaller thickness and a larger diameter than the valve element <NUM>. The outer peripheral edge of the flange portion <NUM> is held between the first holding member <NUM> and the second holding member <NUM>, and thereby the diaphragm valve <NUM> is held by the first holding member <NUM> and the second holding member <NUM>.

The valve element <NUM> has a short vertical hole <NUM> extending from a sidewall of the valve element <NUM> in a radial direction and a horizontal hole <NUM> connecting to the vertical hole <NUM> so as to be substantially orthogonal to the vertical hole <NUM> and extending toward the second holding member <NUM>. The vertical hole <NUM> and the horizontal hole <NUM> connect the valve chamber <NUM> and a pilot chamber <NUM> (described below). That is, the vertical hole <NUM> and the horizontal hole <NUM> constitute a first pilot path for introducing compressed air into the pilot chamber <NUM>.

The second holding member <NUM> has a recess formed in an end face thereof that faces the diaphragm valve <NUM>. The recess and an end face of the diaphragm valve <NUM> facing the second holding member <NUM> form the pilot chamber <NUM>. The pilot chamber <NUM> communicates with a second pilot path <NUM> extending linearly toward the holder <NUM>.

An end of the discharge channel <NUM> has a discharge port exposed to the atmosphere. A predetermined member such as a nozzle or a diffuser (not illustrated) may be attached to the discharge port. The discharge channel <NUM> has an outlet port of a pilot exit path <NUM> opened at a position upstream of the discharge port. The pilot exit path <NUM> bends or inclines and extends toward the holder <NUM>.

The holder <NUM> has a valve entrance path <NUM>, a valve attachment port <NUM>, and a valve exit path <NUM>. The valve entrance path <NUM> extends from the exit opening of the second pilot path <NUM> to the valve attachment port <NUM>. The valve exit path <NUM> extends from the valve attachment port <NUM> to an inlet port of the pilot exit path <NUM>. The valve exit path <NUM> has an opening facing the valve attachment port <NUM>, and a ring-shaped second seat <NUM> protrudes from the vicinity of the opening. The gap between the second holding member <NUM> and the holder <NUM> is sealed with a third seal member <NUM> and a fourth seal member <NUM>.

The solenoid valve <NUM> is attached to the valve attachment port <NUM>. Specifically, the valve attachment port <NUM> has a first edge part (not illustrated) on the inner circumferential wall. The solenoid valve <NUM> includes a tubular body <NUM> with a substantially T-shaped cross-section. The tubular body <NUM> includes a large diameter portion <NUM> having a second edge part (not illustrated) formed on the outer circumferential wall. The second edge part engages with the first edge part, and thereby the solenoid valve <NUM> is held by the holder <NUM>. The valve attachment port <NUM> functions as a valve chamber of the solenoid valve <NUM>.

As illustrated in <FIG> in detail, the solenoid valve <NUM> includes an electromagnetic coil <NUM> produced by winding wires around a bobbin <NUM>, a fixed core <NUM> and a movable core <NUM> inserted into an insertion hole <NUM> of the bobbin <NUM>, and a valve plug <NUM> held at a distal end of the movable core <NUM>. The bobbin <NUM>, the movable core <NUM>, and the valve plug <NUM> are accommodated inside a casing <NUM>.

The casing <NUM> has an exposure hole <NUM> formed in the right closed surface, and a circular cylindrical portion <NUM> with a small diameter constituting the fixed core <NUM> is exposed through the exposure hole <NUM>. The circular cylindrical portion <NUM> has a recessed groove <NUM> in the side surface. A C-shaped clip <NUM> is engaged into the recessed groove <NUM>, whereby the fixed core <NUM> is positioned and secured in place inside the insertion hole <NUM>.

Most part of a hollow collar member <NUM> is inserted inside the insertion hole <NUM>. Most part of the movable core <NUM> is inserted inside the collar member <NUM>. A left part of the collar member <NUM> is exposed from the casing <NUM> and is bent such that the diameter of the collar member <NUM> increases. The collar member <NUM> includes, at a left end thereof, a flange portion <NUM> formed by causing a circumferential wall portion <NUM> of the collar member <NUM> to rise up. The large diameter portion <NUM> of the tubular body <NUM> is fitted into a space defined by the flange portion <NUM> and the circumferential wall portion <NUM>. The gap between the collar member <NUM> and the holder <NUM> is sealed with a fifth seal member <NUM>.

The movable core <NUM> has an engagement hole <NUM> at the left end. The engagement hole <NUM> has, near an opening thereof, an inner catch portion <NUM> which protrudes radially inward so as to reduce the inner diameter of the engagement hole <NUM>. A head portion of the valve plug <NUM> made of rubber is inserted into the engagement hole <NUM>. The head portion has a truncated cone shape tapered such that the diameter increases toward the base, and a portion with the largest diameter is caught or hooked onto the inner catch portion <NUM>. As a result, the valve plug <NUM> is prevented from dropping off the engagement hole <NUM>. When the head portion is inserted into the engagement hole <NUM>, the head portion elastically contracts as being pressed radially. After being inserted into the engagement hole <NUM>, the head portion returns to the original shape by the elasticity. In this manner, the portion of the head portion having the largest diameter is caught or hooked onto the inner catch portion <NUM>.

An outer catch portion <NUM> is formed in the vicinity of an outer circumference of the inner catch portion <NUM>. A small-diameter end of a return spring <NUM> having a truncated cone appearance is in contact with the outer catch portion <NUM>. A large-diameter end of the return spring <NUM> is in contact with a stepped portion of the collar member <NUM> formed by a difference in diameter. The return spring <NUM> elastically biases the movable core <NUM> toward the valve exit path <NUM>. As a result, when the solenoid valve <NUM> is not energized, the circular cylindrical portion of the valve plug <NUM> having a constant diameter is seated on the second seat <NUM>, to thereby maintain a closed state.

The solenoid valve <NUM> is provided with an energization terminal (not illustrated) that is electrically connected to a power source <NUM> via a lead wire <NUM>. Electric current supplied from the power source <NUM> flows through the electromagnetic coil <NUM> via the lead wire <NUM> and the energization terminal. A control switch <NUM> that operates under the control of a control circuit <NUM> is disposed on the lead wire <NUM> at a point away from the solenoid valve <NUM>.

The compressed-fluid discharge control device <NUM> according to the first embodiment is basically configured as above. Next, the operational effects thereof will be described.

Compressed air is sent from the compressed-air supply source to the first supply channel <NUM> via the supply pipe and the regulating valve <NUM> and then introduced from the first supply channel <NUM> into the storage chamber <NUM>. When the storage chamber <NUM> is filled with compressed air, the compressed air flows into the pilot chamber <NUM> through the second supply channel <NUM>, the communication channel <NUM> (communicating hole <NUM>), the valve chamber <NUM>, and the vertical hole <NUM> and the horizontal hole <NUM> (first pilot path) created in the diaphragm valve <NUM>. The compressed air is then introduced into the valve attachment port <NUM> through the second pilot path <NUM> and the valve entrance path <NUM>. The compressed air is blocked from flowing further since the valve plug <NUM> is seated on the second seat <NUM>.

In this state, the internal pressure produced by the compressed air inside the valve chamber <NUM> and the internal pressure produced by the compressed air inside the pilot chamber <NUM> are balanced. Thus, the diaphragm valve <NUM> is kept in a state in which the valve element <NUM> is seated on the first seat <NUM>. That is, the diaphragm valve <NUM> is closed, and communication between the storage chamber <NUM> and the discharge channel <NUM> is thus blocked.

To perform cleaning or the like by blowing air, an operator operates the control switch <NUM> via the control circuit <NUM>. This causes the control switch <NUM> to be closed (turned on), and electric current is supplied from the power source <NUM> to the electromagnetic coil <NUM> through the lead wire <NUM> and the energization terminal. That is, the solenoid valve <NUM> is energized, and the fixed core <NUM> is magnetized. The resulting magnetic effect occurring in the fixed core <NUM> causes the movable core <NUM> to be attracted and displaced toward the fixed core <NUM> as illustrated in <FIG>. As a result, the valve plug <NUM> held at the left end of the movable core <NUM> is separated from the second seat <NUM>. With this separation, the return spring <NUM> is compressed.

As the valve plug <NUM> is separated from the second seat <NUM>, the valve entrance path <NUM> and the valve exit path <NUM> communicate with each other via the valve attachment port <NUM>. Consequently, the pilot chamber <NUM> communicates with the discharge channel <NUM> via the second pilot path <NUM>, the valve entrance path <NUM>, the valve attachment port <NUM> (valve chamber of the solenoid valve <NUM>), the valve exit path <NUM>, and the pilot exit path <NUM>. As a result, the compressed air inside the pilot chamber <NUM> flows into the discharge channel <NUM> and is discharged from the discharge port. In this manner, closing of the control switch <NUM> causes the pilot chamber <NUM> to be opened and thus causes the compressed air inside the pilot chamber <NUM> to be discharged.

Due to the above discharge, the internal pressure in the pilot chamber <NUM> becomes smaller than the internal pressure in the valve chamber <NUM>. This causes the valve element <NUM> of the diaphragm valve <NUM> to be pushed by the compressed air inside the valve chamber <NUM> and, as a result, the valve element <NUM> is separated from the first seat <NUM> immediately. That is, the diaphragm valve <NUM> opens immediately. The diaphragm valve <NUM> is configured to open as the compressed air inside the pilot chamber <NUM> is discharged in this manner, resulting in a high response speed.

As the diaphragm valve <NUM> opens, the storage chamber <NUM> communicates with the discharge channel <NUM>. In a case where the flow control path <NUM> is not fully closed by the needle <NUM> of the regulating valve <NUM> (see <FIG>), the first supply channel <NUM> also communicates with the discharge channel <NUM>.

The storage chamber <NUM> is filled with a predetermined volume of compressed air in advance. In other words, a predetermined amount of compressed air is already stored in the storage chamber <NUM>. Consequently, the compressed air inside the storage chamber <NUM> is introduced into the discharge channel <NUM> via the second supply channel <NUM> and the valve chamber <NUM>, and joins with the compressed air sent from the pilot chamber <NUM> to the discharge channel <NUM> as described above. As a result, compressed air is discharged from the discharge port at a high flow rate all at once. Thus, as indicated by a solid line in <FIG>, an instantaneous high discharge pressure (peak pressure) can be obtained immediately after the start of discharge (blowing). The upper limit of the peak pressure can be set according to the uses of the device by replacing the body portion <NUM> forming the storage chamber <NUM> and thereby changing the volume of the storage chamber <NUM> as appropriate. That is, the compressed air is prevented from being discharged at a higher pressure than necessary.

In <FIG>, the discharge pressure of a compressed-fluid discharge control device according to a prior art is indicated by a broken line. It is understood from <FIG> that the discharge pressure is substantially constant from the start to the end of discharge in the prior art and, by contrast, that the peak pressure can be obtained immediately after the start of discharge in the first embodiment. In this manner, in the first embodiment, the diaphragm valve <NUM> is opened by opening the pilot chamber <NUM>, and in addition, the compressed air stored in the storage chamber <NUM> is discharged all at once. As a result, the peak pressure can be easily obtained by simply closing the control switch <NUM>.

In addition, by arranging the control circuit <NUM> at a position away from a place where the blowing is performed, the control switch <NUM> can be closed in a different place from a worksite where blowing is performed, in other words, the solenoid valve <NUM> can be operated remotely. Thus, even in a case where water sprays all over the worksite, the operator is prevented from getting wet.

When the flow control path <NUM> is fully closed by the needle <NUM> of the regulating valve <NUM>, communication between the first supply channel <NUM> and the storage chamber <NUM> is blocked. Consequently, even when the control switch <NUM> is kept closed, blowing ends as discharge of the compressed air inside the storage chamber <NUM> ends. To perform blowing again, the regulating valve <NUM> may be opened to refill the storage chamber <NUM> with compressed air.

On the other hand, when the needle <NUM> of the regulating valve <NUM> is withdrawn to thereby open the orifice <NUM> at a predetermined opening degree, the first supply channel <NUM> and the storage chamber <NUM> communicate with each other. Consequently, compressed air is supplied to the storage chamber <NUM> via the first supply channel <NUM> while the compressed air inside the storage chamber <NUM> is discharged. Since the diaphragm valve <NUM> is open at this moment, the compressed air is not stored in the storage chamber <NUM> but flows to the discharge channel <NUM> through the storage chamber <NUM>, the second supply channel <NUM>, and the valve chamber <NUM>. As a result, discharge of compressed air continues.

The pressure (discharge pressure) of the compressed air discharged from the discharge port at this moment is lower than the discharge pressure immediately after the start of discharge. That is, as illustrated in <FIG>, blowing continues at a constant low pressure. The discharge pressure at this moment can be adjusted according to the opening degree of the regulating valve <NUM>. That is, the discharge pressure increases as the opening degree of the regulating valve <NUM> increases.

In this manner, in the first embodiment, the discharge pressure immediately after the start of discharge is set high (the peak pressure can be obtained) by discharging the compressed air stored in the storage chamber <NUM> first, and the subsequent discharge pressure is set low. In general, kinetic frictional force that acts on an object in motion is smaller than static friction force that acts on an object at rest. Consequently, even when the discharge pressure is changed as described above, it is possible to bring chips and dust and the like from a state of rest into a state of motion by the peak pressure immediately after the start of discharge, and keep the chips and dust in a state of motion by the subsequent low discharge pressure. As a result, the chips and dust can be easily removed.

Moreover, compressed air only needs to be discharged at a high flow rate in a very short time, in order to increase the discharge pressure. That is, compressed air does not need to be continuously discharged at a high flow rate. This results in a reduction in the consumption of compressed air and thus leads to energy savings.

In addition, in the first embodiment, compressed air retained in the pilot chamber <NUM>, the second pilot path <NUM>, and the valve entrance path <NUM> is used for blowing as described above. This further increases the peak pressure immediately after the start of discharge while reducing the consumption of compressed air to thereby save more energy.

To end blowing, it is only necessary to open (turn off) the control switch <NUM> by operator's operations or automatic control of the control circuit <NUM>. As a result of this, the energization of the electromagnetic coil <NUM> is stopped, and thereby the magnetic effect of the fixed core <NUM> disappears. Consequently, the return spring <NUM> that has been compressed expands and elastically biases the movable core <NUM>. As a result, the valve plug <NUM> is displaced toward the valve exit path <NUM> and seated on the second seat <NUM> (see <FIG> and <FIG>).

In other words, the solenoid valve <NUM> is closed and communication between the pilot chamber <NUM> and the discharge channel <NUM> is blocked. Meanwhile, compressed air is supplied from the valve chamber <NUM> to the pilot chamber <NUM> via the vertical hole <NUM> and the horizontal hole <NUM>. This increases the internal pressure in the pilot chamber <NUM> compared with the internal pressure in the valve chamber <NUM> and thus causes the valve element <NUM> of the diaphragm valve <NUM> to be seated on the first seat <NUM>. That is, the diaphragm valve <NUM> is closed, so that the communication between the storage chamber <NUM> and the discharge channel <NUM> and the communication between the valve chamber <NUM> and the discharge channel <NUM> are blocked.

As illustrated in <FIG>, the holder <NUM> and the solenoid valve <NUM> may be disposed away from the second holding member <NUM>. In this case, a pipe <NUM> for drawing air into the valve may be disposed between the second pilot path <NUM> and the valve entrance path <NUM>, and a pipe <NUM> for drawing air out of the valve may be disposed between the valve exit path <NUM> and the pilot exit path <NUM>. In this case, the solenoid valve <NUM> can be disposed in a position away from a worksite where, for example, water sprays all over. This prevents the solenoid valve <NUM> from getting wet.

Reducing the stroke of the diaphragm valve <NUM> further increases the response speed. Next, a structure that embodies the above will be described as a second embodiment. The same reference numbers and symbols are used for components identical to those in <FIG>, and the detailed descriptions will be omitted. In <FIG>, the lead wire <NUM>, the power source <NUM>, the control circuit <NUM>, and the control switch <NUM> are not illustrated.

A compressed-fluid discharge control device <NUM> according to the second embodiment illustrated in <FIG> includes a flow control unit <NUM> serving as an example of a displacement limiting unit. As the flow control unit <NUM> basically has a structure similar to that described in <CIT>, only an outline thereof will be described.

The flow control unit <NUM> includes a flow adjustment section <NUM>, a displaceable member <NUM>, and a stopper <NUM> serving as a contact member. The displaceable member <NUM> is inserted into a screw hole <NUM> formed in the holder <NUM> and an insertion hole <NUM> formed in the second holding member <NUM>. A left end part of the displaceable member <NUM> protrudes into the pilot chamber <NUM>. The stopper <NUM> is attached to the left end part of the displaceable member <NUM>.

The flow adjustment section <NUM> also functions as an operating mechanism for adjusting the protruding length of the displaceable member <NUM> inside the pilot chamber <NUM> and thereby limiting the displacement of the valve element <NUM>, in other words, the opening degree of the diaphragm valve <NUM>. The flow adjustment section <NUM> includes a housing <NUM> accommodating the operating mechanism, and a knob <NUM> rotatably attached to the housing <NUM>. The housing <NUM> is detachably attached to the holder <NUM>.

As illustrated in <FIG> in detail, the housing <NUM> is dividable into a first case <NUM> and a second case <NUM>. The second case <NUM> has a dome shape to have an interior space with a predetermined volume when mounted on the first case <NUM>. The second case <NUM> has an opening with a relatively large inner diameter at an end part thereof facing the first case <NUM>, and a right end part of the first case <NUM> is inserted into the opening. Moreover, a plurality of (for example, four) locking holes (not illustrated) are formed in the side surface of the second case <NUM> at regular intervals. Mounting hooks <NUM> protruding from the side surface of the first case <NUM> are inserted into the locking holes. The first case <NUM> and the second case <NUM> are connected to each other by the insertion of the mounting hooks <NUM> into the locking holes.

The knob <NUM> functions as an operating portion that adjusts the flow rate of fluid inside the compressed-fluid discharge control device <NUM> by being rotated relative to the housing <NUM> by the operator. That is, the knob <NUM> has a tubular shape having a bottom on the right and includes a tubular fitting part <NUM> extending leftward from the center of the bottom inside the tube. The fitting part <NUM> is fitted on a rotation transmitting member <NUM>. The inner circumferential surface (female type) of the fitting part <NUM> and the outer circumferential surface (male type) of the rotation transmitting member <NUM> are fitted with each other such that the knob <NUM> is displaceable in the left and right direction. Thus, the rotational force of the knob <NUM> is transmitted smoothly to the rotation transmitting member <NUM>.

The rotation transmitting member <NUM> controls the displacements of the displaceable member <NUM> and the stopper <NUM> and has a predetermined length. The rotation transmitting member <NUM> includes a tubular part <NUM> having a hollow cylindrical shape and a post part <NUM> extending rightward from an end face of the tubular part <NUM>.

The tubular part <NUM> has a hollow interior formed as a space inside which a shaft portion <NUM> of the displaceable member <NUM> is movable back and forth in the axial direction. The tubular part <NUM> includes an internal thread part formed in the inner circumferential wall, and an external thread part formed on the circumferential sidewall of the shaft portion <NUM> of the displaceable member <NUM> is screw-engaged into the internal thread part and the screw hole <NUM>.

The post part <NUM> has a circular cylindrical shape with an outer diameter smaller than that of the tubular part <NUM> and extends rightward through the housing <NUM>. A right end part of the post part <NUM> is connected to the knob <NUM>.

The displaceable member <NUM> is a solid round-rod member extending in the left and right direction. The displaceable member <NUM> includes a connection end portion <NUM> and the shaft portion <NUM>. The stopper <NUM> is disposed on the end face of the connection end portion <NUM> and can be brought into contact with the end face of the valve element <NUM>.

The shaft portion <NUM> has a predetermined length along the axial direction and includes the external thread part formed on the sidewall as described above. The external thread part is screw-engaged into the internal thread part formed in the inner surface of the rotation transmitting member <NUM> extending toward the shaft portion <NUM>. Thus, by rotating the rotation transmitting member <NUM>, the displaceable member <NUM> including the shaft portion <NUM> can be moved back and forth (displaced) in the left and right direction.

In addition to the housing <NUM>, the knob <NUM>, and the rotation transmitting member <NUM>, the flow adjustment section <NUM> includes an indicator ring <NUM> disposed inside the housing <NUM>.

The indicator ring <NUM> is rotatably housed inside the dome-shaped second case <NUM>. The second case <NUM> includes a display window (not illustrated) in the side surface, and graduations on the indicator ring <NUM> are visible through the display window.

The second case <NUM> includes a tubular protruding part <NUM> having a predetermined inner diameter. The protruding part <NUM> is inserted into the knob <NUM> and rotatably supports the knob <NUM>. A knob-rotation limiting part <NUM> is disposed on a right end part of the outer circumferential surface of the protruding part <NUM>. Furthermore, a first annular protrusion <NUM> and a second annular protrusion <NUM> are formed on the left of the knob-rotation limiting part <NUM>. An inner protruding part <NUM> at a left end part of the knob <NUM> can engage with the first annular protrusion <NUM> and the second annular protrusion <NUM> in a stepwise manner.

A plurality of ridges (not illustrated) are formed on the outer circumferential surface of a wall of the knob <NUM> enclosing the fitting part <NUM> so that the operator can grip the knob <NUM> easily. Moreover, a contact part <NUM> brought into contact with the knob-rotation limiting part <NUM> is disposed on a right end of the inner circumferential surface of the wall. The inner protruding part <NUM> protruding radially inward is disposed on a left end of the inner circumferential surface of the wall.

The knob <NUM> can be switched between a rotatable state and a non-rotatable state according to the position in the left and right direction relative to the protruding part <NUM>. That is, when the knob <NUM> is disposed in a left position where the inner protruding part <NUM> is caught by the second annular protrusion <NUM> on the protruding part <NUM>, the contact part <NUM> of the knob <NUM> is in contact with the knob-rotation limiting part <NUM>, and thus the rotation of the knob <NUM> is restricted. To rotate the knob <NUM>, the knob <NUM> is moved to the right to get over the second annular protrusion <NUM>, so that the contact part <NUM> is separated from the knob-rotation limiting part <NUM>. This allows the knob <NUM> to rotate relative to the second case <NUM>.

The post part <NUM> of the rotation transmitting member <NUM> is inserted into a hole part <NUM> of the indicator ring <NUM> in a state where the indicator ring <NUM> is disposed in place. The indicator ring <NUM> includes an internal-contact tooth part (not illustrated), and the rotation transmitting member <NUM> includes a pair of meshing parts (not illustrated) on the outer circumferential surface. The indicator ring <NUM> is rotated only when the meshing parts engage (mesh) with the internal-contact tooth part.

In a case where the flow rate of pressurized fluid flowing inside the compressed-fluid discharge control device <NUM> configured as above needs to be controlled, the operator grips the knob <NUM> and moves the knob <NUM> to the right. This causes the inner protruding part <NUM> at the left end of the knob <NUM> to engage with the first annular protrusion <NUM>, and at the same time, the meshing parts becomes engaged with the internal-contact tooth part. The operator then rotates the knob <NUM> to thereby rotate the rotation transmitting member <NUM> and the indicator ring <NUM>. Along with the rotation of the rotation transmitting member <NUM>, the displaceable member <NUM> moves to the left or right inside the hollow interior of the tubular part <NUM> while rotating. With the movement of the displaceable member <NUM>, the stopper <NUM> moves to the left or right inside the pilot chamber <NUM>.

The position of the stopper <NUM> can be acquired from the graduations on the indicator ring <NUM>. That is, for example, in a case where the flow rate of pressurized fluid inside the compressed-fluid discharge control device <NUM> needs to be increased according to the numbers of the graduations, the displaceable member <NUM> and the stopper <NUM> may be set to move to the right as the numbers of the graduations become larger.

When the displayed graduation indicates a predetermined value, the operator stops rotating the knob <NUM>. Then, the operator pushes the knob <NUM> to the left so that the inner protruding part <NUM> of the knob <NUM> at the left end engages with the second annular protrusion <NUM> and that the meshing parts are released from the engagement with the internal-contact tooth part. As a result, the knob <NUM> is locked, so that the rotation of the knob <NUM> is prevented and the displacement of the displaceable member <NUM> and the stopper <NUM> are prevented. In this manner, the inner protruding part <NUM> and the second annular protrusion <NUM> function as a lock means.

The stopper <NUM> serving as the contact member is positioned and secured in place by the above locking action. As a result, the maximum opening degree of the diaphragm valve <NUM> is kept constant, and the flow rate of compressed air when the diaphragm valve <NUM> is open at the maximum opening degree becomes stable. Moreover, the operator becomes unable to adjust the opening degree easily, and thus it is possible to prevent, for example, discharge of more than the required amount set by a manager in advance.

Operations of the compressed-fluid discharge control device <NUM> according to the second embodiment configured as above will now be described below.

As in the first embodiment, when the compressed air is only introduced into the pilot chamber <NUM>, the second pilot path <NUM>, and the valve entrance path <NUM>, the diaphragm valve <NUM> is kept closed since the internal pressure produced by the compressed air inside the valve chamber <NUM> and the internal pressure produced by the compressed air inside the pilot chamber <NUM> are balanced. Thus, the communication between the storage chamber <NUM> and the discharge channel <NUM> is blocked.

When the operator performs cleaning or the like by blowing air, the operator operates the control switch <NUM> via the control circuit <NUM> as in the first embodiment. This causes the control switch <NUM> to be closed (turned on), and an electric current is supplied from the power source <NUM> to the electromagnetic coil <NUM> through the lead wire <NUM> and the energization terminal. The fixed core <NUM> is magnetized, and thus a magnetic effect occurs. As a result, as illustrated in <FIG>, the movable core <NUM> is attracted and displaced toward the fixed core <NUM>, and the valve plug <NUM> held at the left end of the movable core <NUM> is separated from the second seat <NUM>. With this separation, the return spring <NUM> is compressed.

As the valve plug <NUM> is separated from the second seat <NUM>, the valve entrance path <NUM> and the valve exit path <NUM> communicate with each other via the valve attachment port <NUM> (valve chamber of the solenoid valve <NUM>). Consequently, the pilot chamber <NUM> communicates with the discharge channel <NUM> via the second pilot path <NUM>, the valve entrance path <NUM>, the valve attachment port <NUM>, the valve exit path <NUM>, and the pilot exit path <NUM>. As a result, the compressed air inside the pilot chamber <NUM> flows into the discharge channel <NUM> and is discharged from the discharge port. In this manner, closing of the control switch <NUM> causes the pilot chamber <NUM> to be opened and thus causes the compressed air inside the pilot chamber <NUM> to be discharged.

When the internal pressure inside the pilot chamber <NUM> becomes smaller than the internal pressure inside the valve chamber <NUM> on the basis of the phenomenon described above, the valve element <NUM> of the diaphragm valve <NUM> is pushed by the compressed air inside the valve chamber <NUM> and, as a result, the valve element <NUM> is separated from the first seat <NUM> immediately. That is, the diaphragm valve <NUM> opens immediately.

As illustrated in <FIG>, the displacement of the valve element <NUM> in a direction away from the first seat <NUM> stops when the end face of the valve element <NUM> comes into contact with the stopper <NUM>. That is, further displacement of the valve element <NUM> is stopped by the stopper <NUM>. This determines the separation distance between the valve element <NUM> and the first seat <NUM>, in other words, the opening degree of the diaphragm valve <NUM>. The compressed air flowing from the interior of the storage chamber <NUM> and the compressed air sent out from the pilot chamber <NUM> are discharged out of the discharge channel <NUM> at a flow rate corresponding to the opening degree.

The positions of the displaceable member <NUM> and the stopper <NUM> are changed by rotating the knob <NUM>. As the protruding length of the stopper <NUM> into the pilot chamber <NUM> increases, the displacement of the valve element <NUM> decreases, and thus the opening degree of the diaphragm valve <NUM> decreases. As a result, the flow rate of compressed air, that is, the amount of discharge decreases. Conversely, as the protruding length of the stopper <NUM> decreases, the displacement of the valve element <NUM> and the opening degree of the diaphragm valve <NUM> increase, and the flow rate of compressed air, that is, the amount of discharge increases.

As can be understood from this, the position where the stopper <NUM> comes into contact with the valve element <NUM> determines the opening degree of the diaphragm valve <NUM> and, as a result, the discharge amount of compressed air is determined. That is, the flow control unit <NUM> limits the maximum flow rate and the peak pressure of compressed air.

The protruding length of the stopper <NUM> can be finely changed by rotating the knob <NUM>. Consequently, the maximum flow rate of compressed air discharged from the discharge channel <NUM> can be finely changed. That is, the discharge amount of compressed air and the peak pressure can be precisely limited. This prevents discharge of more than the required amount from the compressed-fluid discharge control device <NUM>. Moreover, reducing the displacement, in other words, the stroke, of the diaphragm valve <NUM> further increases the response speed.

As in the first embodiment, the volume of the storage chamber <NUM> can be changed as appropriate by replacing the body portion <NUM> constituting the first housing <NUM>. This allows the upper limit of the peak pressure to be set according to the uses of the device and thus prevents compressed air from being discharged at a higher pressure than necessary.

The second embodiment also produces operational effects similar to those of the first embodiment as a matter of course.

The present invention is not limited in particular to the first to second embodiments described above, and various changes can be made thereto without departing from the scope of the present invention.

Claim 1:
A compressed-fluid discharge control device (<NUM>) configured to control discharge of compressed fluid, comprising:
a valve chamber (<NUM>) provided with a seat (<NUM>) and configured to communicate with a supply channel (<NUM>, <NUM>) through which the compressed fluid is supplied and a discharge channel (<NUM>) including a discharge port through which the compressed fluid is discharged;
a diaphragm valve (<NUM>) including a pilot path (<NUM>, <NUM>) and configured to block communication between the supply channel (<NUM>, <NUM>) and the discharge channel (<NUM>) by being seated on the seat (<NUM>) and to establish the communication by being separated from the seat (<NUM>);
a pilot-chamber opening and closing valve configured to open and close a pilot chamber (<NUM>) into which the compressed fluid is introduced from the supply channel (<NUM>, <NUM>) via the pilot path (<NUM>, <NUM>), wherein the pilot-chamber opening and closing valve includes a solenoid valve (<NUM>) configured to be opened when energized and to be closed when de-energized, and when the pilot-chamber opening and closing valve is opened to open the pilot chamber (<NUM>), the diaphragm valve (<NUM>) is separated from the seat (<NUM>), and thereby the supply channel (<NUM>, <NUM>) and the discharge channel (<NUM>) communicate with each other;
characterized in that a storage chamber configured to store the compressed fluid is disposed between the supply channel and the valve chamber; and
wherein
when the diaphragm valve (<NUM>) is in a closed state, the compressed fluid supplied from the supply channel (<NUM>) is stored in the storage chamber (<NUM>);
immediately after the diaphragm valve (<NUM>) is opened, the compressed fluid stored in the storage chamber (<NUM>) is discharged at a maximum discharge pressure via the discharge channel (<NUM>); and subsequently the diaphragm valve (<NUM>) is kept open and the compressed fluid that has flowed through the storage chamber (<NUM>) is discharged at a discharge pressure lower than the maximum discharge pressure via the discharge channel (<NUM>).