Flow controller and driving apparatus including the same

A flow controller that changes the flow rate of air exhausted from an air cylinder in mid-stroke includes a first switching valve displaced from a first position to a second position under the effect of pilot air, and causing one port of the air cylinder to communicate with a first channel at the first position, exhausting air exhausted from the one port of the air cylinder while reducing the flow rate of the air using a first regulating valve at the second position. Since the pilot air is taken into the first switching valve from a second channel in a system different from the system of the first channel, a second regulating valve can be adjusted without being affected by the degree of opening of the first regulating valve.

TECHNICAL FIELD

The present invention relates to a flow controller capable of changing the operating speed of an air cylinder in mid-stroke and a driving apparatus including the same.

BACKGROUND ART

In a case where a shock absorber cannot be attached to a cylinder or where the speed of the cylinder needs to be changed at a position other than the stroke ends, a speed controller (flow controller) capable of changing the speed in mid-stroke using an air circuit has been used (see Japanese Patent No. 5578502).

The speed controller described in Japanese Patent No. 5578502 includes a three-way shuttle valve on a channel between a high-pressure air supply source and an air cylinder to guide exhaust air from the air cylinder to an exhaust channel different from the channel for introducing high-pressure air. The exhaust air is exhausted via a switching valve and a first throttle valve provided for the exhaust channel and a second throttle valve. The switching valve switches the channels when the piston is in the vicinity of the stroke ends such that the exhaust air passes through the first throttle valve reducing the stroke speed to reduce impact on the air cylinder during an exhausting process.

SUMMARY OF INVENTION

To operate the known flow controller properly, it is necessary to match three adjustment processes with one another, i.e., adjustment of a regulating needle (throttle valve) that regulates operation timing of the switching valve, adjustment of the first throttle valve, and adjustment of the second throttle valve.

However, since the three adjustment processes affect each other, that is, one adjustment result affects the other two adjustment processes, the above-described speed controller cannot be easily adjusted.

Thus, the present invention has the object of providing an easily adjustable flow controller and a driving apparatus including the same.

According to one aspect of the present invention, a flow controller that changes a flow rate of air supplied or exhausted through at least one of a first channel communicating with one port of an air cylinder and a second channel communicating with another port of the air cylinder in mid-stroke, comprises a first switching valve configured to be displaced from a first position to a second position under an effect of pilot air, cause the one port of the air cylinder to communicate with the first channel at the first position, and cause the one port of the air cylinder to communicate with an air outlet via a first regulating valve at the second position, a first introduction path configured to guide the pilot air from the second channel to the first switching valve, and a second regulating valve provided for the first introduction path and configured to adjust timing of displacement of the first switching valve by regulating a flow rate of the pilot air.

According to another aspect of the present invention, a driving apparatus comprises the flow controller according to the one aspect, a high-pressure air supply source configured to supply high-pressure air to the air cylinder via the first channel or the second channel, and an air outlet configured to exhaust air from the air cylinder via the first channel or the second channel.

In accordance with the flow controller and the driving apparatus according to the above-described aspects, the pilot air is taken into the first switching valve from the second channel in a different system that does not communicate with the first regulating valve connected to the first switching valve. Thus, a throttle valve that regulates switching timing can be easily adjusted without being affected by the adjustment state of the first regulating valve.

DESCRIPTION OF EMBODIMENTS

A preferred embodiment according to the present invention will be described in detail below with reference to the accompanying drawings.

As illustrated inFIG. 1, a driving apparatus10according to an embodiment is used to drive an air cylinder100and includes a first channel14connected to one end of the air cylinder100and a second channel16connected to another end. The driving apparatus10further includes a flow controller12, a high-pressure air supply source46, air outlets48aand48b, an operation switching valve40, and speed controllers42and44.

The air cylinder100is a double-acting cylinder used for, for example, automated equipment and production lines, and includes a piston106partitioning a cylinder chamber100aand a piston rod108connected to the piston106. A pressure chamber adjacent to the head of the piston106has a head-side port102. Moreover, a pressure chamber adjacent to the rod of the piston106has a rod-side port104. The second channel16is connected to the head-side port102, and the first channel14is connected to the rod-side port104.

The first channel14is an air channel extending from the operation switching valve40to the rod-side port104of the air cylinder100. Moreover, the second channel16is an air channel extending from the operation switching valve40to the head-side port102of the air cylinder100. Introduction of high-pressure air into the air cylinder100and exhaust of air inside the air cylinder100are performed via the first channel14and the second channel16. The piston rod108is pushed out by high-pressure air introduced via the second channel16(working process). Moreover, the piston rod108is drawn in by high-pressure air introduced via the first channel14(retracting process).

The flow controller12is connected to the first channel14and the second channel16to change the operating speed of the air cylinder100in mid-stroke. The flow controller12includes a first cylinder port12cand a second cylinder port12dto which pipes from the air cylinder100are connected and a first connection port12aand a second connection port12bto which pipes from the operation switching valve40are connected. The flow controller12further includes a first flow rate adjustment section13A controlling the flow rate in the first channel14and a second flow rate adjustment section13B controlling the flow rate in the second channel16.

The first flow rate adjustment section13A of the flow controller12includes a first switching valve20, a first regulating valve28, and a second regulating valve26. The first switching valve20is a three-way valve including first connection portions20a, second connection portions20b, and third connection portions20c. The first switching valve20is displaced from a first position to a second position by pilot air supplied via the second regulating valve26. That is, the first switching valve20is driven by a drive piston22driven in response to the pilot air and a biasing member24returning the first switching valve20to the first position. A specific structure of the first switching valve20will be described later with reference toFIG. 3. The first connection portions20acommunicate with the first cylinder port12cvia a channel14b, the second connection portions20bcommunicate with the first connection port12avia a channel14a, and the third connection portions20ccommunicates with one of the air outlets48avia the first regulating valve28.

When the first switching valve20is at the first position, the first connection portions20aand the second connection portions20bare connected to each other, and thereby the first cylinder port12cand the first connection port12acommunicate with each other. Moreover, when the first switching valve20is at the second position (seeFIG. 8), the first connection portions20aand the third connection portions20care connected to each other, and thereby the first cylinder port12cand the first regulating valve28(and the air outlet48a) communicate with each other.

The first regulating valve28is configured by an variable throttle valve capable of varying a flow rate, and is configured to regulate the operating speed of the air cylinder100to a second speed by reducing the flow rate of air flowing from the third connection portions20cto the air outlet48a. The first regulating valve28is not limited to the variable throttle valve but may be a fixed throttle valve allowing air to pass through the throttle valve at a fixed flow rate.

The second regulating valve26is disposed on a first introduction path21. One end of the first introduction path21is connected to a channel16a(second channel16) between a second switching valve30and the operation switching valve40, and another end of the first introduction path21is connected to the drive piston22of the first switching valve20. The first introduction path21introduces pilot air from the second channel16into the first switching valve20. The second regulating valve26includes a throttle valve120capable of varying a flow rate and a check valve122connected in parallel to the throttle valve120. The throttle valve120is configured to reduce the flow rate of pilot air flowing from the second channel16to the drive piston22of the first switching valve20. The check valve122is disposed in a direction to allow the passage of air flowing from the drive piston22to the second channel16. The check valve122is configured to exhaust the pilot air remaining in the drive piston22to the second channel16when the pressure in the second channel16decreases, so that the first switching valve20smoothly returns to the initial position.

The second flow rate adjustment section13B of the flow controller12includes the second switching valve30, a third regulating valve38, and a fourth regulating valve36. The second switching valve30is a three-way valve including a first connection portion30a, a second connection portion30b, and a third connection portion30c, and is displaced from a first position to a second position by pilot air supplied via the fourth regulating valve36. That is, the second switching valve30is driven by a drive piston32driven in response to the pilot air and a biasing member34returning the second switching valve30to the first position. The specific structure of the second switching valve30is similar to that of the first switching valve20. The first connection portion30acommunicates with the second cylinder port12dvia a channel16b, the second connection portion30bcommunicates with the second connection port12bvia the channel16a, and the third connection portion30ccommunicates with the other of the air outlets48avia the third regulating valve38.

When the second switching valve30is at the first position, the first connection portion30aand the second connection portion30bare connected to each other, and thereby the second cylinder port12dand the second connection port12bcommunicate with each other. Moreover, when the second switching valve30is at the second position (seeFIG. 10), the first connection portion30aand the third connection portion30care connected to each other, and thereby the second cylinder port12dand the third regulating valve38communicate with each other.

The third regulating valve38comprises an variable throttle valve capable of varying a flow rate, and is configured to regulate the operating speed of the air cylinder100to a fourth speed by reducing the flow rate of air flowing from the third connection portion30cto the air outlet48a. The third regulating valve38is not limited to the variable throttle valve but may be a fixed throttle valve allowing air to pass through the throttle valve at a fixed flow rate.

The fourth regulating valve36is disposed on a second introduction path31. One end of the second introduction path31is connected to the channel14a(first channel14) between the first switching valve20and the operation switching valve40, and another end of the second introduction path31is connected to the drive piston32of the second switching valve30. The second introduction path31introduces pilot air from the first channel14into the second switching valve30. The fourth regulating valve36includes a throttle valve130capable of varying a flow rate and a check valve132connected in parallel to the throttle valve130. The throttle valve130is configured to reduce the flow rate of pilot air flowing from the first channel14to the drive piston32of the second switching valve30. The check valve132is disposed to face a direction allowing the passage of air flowing from the drive piston32to the first channel14. The check valve132is configured to exhaust the pilot air remaining in the drive piston32to the first channel14when the pressure in the first channel14decreases so that the second switching valve30smoothly returns to the initial position. The first regulating valve28, the second regulating valve26, the third regulating valve38, and the fourth regulating valve36may be commercially available needle valves with a reverse flow check valve.

The speed controller42is disposed on a pipe14cconnecting the first cylinder port12cof the flow controller12and the rod-side port104of the air cylinder100to each other. The speed controller42includes a throttle valve42acapable of varying a flow rate and a check valve42bconnected in parallel to the throttle valve42a. The check valve42bis connected in a direction allowing the passage of air flowing from the first cylinder port12cto the rod-side port104and checking air flowing in the opposite direction. That is, the speed controller42is a meter-out speed controller regulating the speed of the stroke of the air cylinder100to a first speed by reducing the flow rate of air exhausted from the rod-side port104of the air cylinder100.

The speed controller44is disposed on a pipe16cconnecting the second cylinder port12dof the flow controller12and the head-side port102of the air cylinder100to each other. The speed controller44includes a throttle valve44acapable of varying a flow rate and a check valve44bconnected in parallel to the throttle valve44a. The check valve44bis connected in a direction allowing the passage of air flowing from the second cylinder port12dto the head-side port102and checking air flowing in the opposite direction. That is, the speed controller44is a meter-out speed controller regulating the operating speed of the air cylinder100during the normal stroke to a third speed by reducing the flow rate of air exhausted from the head-side port102of the air cylinder100.

To regulate the operating speed of the air cylinder100using the flow rate of the air that flows in (meter-in speed control), each of the speed controllers42and44and the check valves42band44bmay be disposed to face the opposite direction. Moreover, the speed controllers42and44are not necessarily disposed on the pipes14cand16c, respectively, and may be disposed at any positions on the first channel14and second channel16, respectively.

The operation switching valve40is configured to connect the high-pressure air supply source46to one of the first channel14and the second channel16while connecting the air outlet48bto the other, and vice versa by switching the connections. The operation switching valve40is a 5-port, 2-position solenoid valve operated based on a predetermined drive signal. The operation switching valve40includes a first port40a, a second port40b, a third port40c, a fourth port40d, and a fifth port40e. When the operation switching valve40is at a first position, the first port40ais connected to the third port40c, and the second port40bis connected to the fourth port40d. Moreover, when the operation switching valve40is at a second position (seeFIG. 8), the first port40ais connected to the fifth port40e, and the second port40bis connected to the third port40c.

The first port40aof the operation switching valve40communicates with the first connection port12aof the flow controller12via pipes, and the second port40bcommunicates with the second connection port12bof the flow controller12via pipes. Moreover, the third port40cof the operation switching valve40communicates with the high-pressure air supply source46via pipes, and the fourth port40dand the fifth port40ecommunicate with the air outlet48b.

That is, when the operation switching valve40is at the first position, the operation switching valve40causes the high-pressure air supply source46to communicate with the first connection port12ato supply high-pressure air to the first channel14, and causes the air outlet48bto communicate with the second connection port12bto expose the second channel16to the atmosphere. Moreover, when the operation switching valve40is at the second position, the operation switching valve40causes the air outlet48bto communicate with the first connection port12ato expose the first channel14to the atmosphere, and causes the high-pressure air supply source46to communicate with the second connection port12bto supply high-pressure air to the second channel16.

The fluid circuit of the driving apparatus10according to this embodiment is configured as above. A specific example of the structure of the flow controller12will now be described.

As illustrated inFIG. 2B, the flow controller12of this embodiment is configured as a module part including an upper housing50and a lower housing52. The lower housing52is provided with the first connection port12a, the second connection port12b(seeFIG. 2A), the first cylinder port12c, and the second cylinder port12d. Moreover, the upper housing50and the lower housing52include therein members constituting the first flow rate adjustment section13A (seeFIG. 1) and the second flow rate adjustment section13B (seeFIG. 1).

As illustrated inFIG. 2A, the upper housing50has a rectangular shape when viewed in plan, and adjustment portions of the first regulating valve28, the second regulating valve26, the third regulating valve38, and the fourth regulating valve36protrude from the top surface of the upper housing50. The first flow rate adjustment section13A extends along a line connecting the first connection port12aand the first cylinder port12c, and the second flow rate adjustment section13B extends along a line connecting the second connection port12band the second cylinder port12d. The first regulating valve28of the first flow rate adjustment section13A is disposed adjacent to the first cylinder port12c, and the second regulating valve26of the first flow rate adjustment section13A is disposed adjacent to the first connection port12a. The first switching valve20is disposed between the first regulating valve28and the second regulating valve26. Moreover, the third regulating valve38of the second flow rate adjustment section13B is disposed adjacent to the second cylinder port12d, and the fourth regulating valve36of the second flow rate adjustment section13B is disposed adjacent to the second connection port12b. The second switching valve30is disposed between the third regulating valve38and the fourth regulating valve36.

As illustrated inFIG. 2B, the air outlets48aare created in a side surface of the upper housing50adjacent to the cylinder ports. Moreover, the lower housing52is provided with fixing holes53aand53bused for securing the flow controller12to a supporting member (not illustrated).

The internal structure of the first flow rate adjustment section13A of the flow controller12will now be described with reference toFIG. 3. As the internal structure of the second flow rate adjustment section13B is similar to that of the first flow rate adjustment section13A illustrated inFIG. 3, the description thereof will be omitted.

As illustrated inFIG. 3, in the flow controller12, the lower housing52and the upper housing50are joined to each other such that the upper housing50is stacked on top of the lower housing52. The upper housing50has a first mounting hole64for installing the first regulating valve28, a second mounting hole61for installing the second regulating valve26, and a third mounting hole54for accommodating the first switching valve20. The first mounting hole64, the second mounting hole61, and the third mounting hole54extend in the height direction of the upper housing50(direction of an arrow Z), and each have an opening in the upper end of the upper housing50. The third mounting hole54passes through the upper housing50and extends further in the lower housing52. The first mounting hole64and the second mounting hole61are separated from each other in a direction of an arrow X illustrated inFIG. 3, and the third mounting hole54is disposed between the first mounting hole64and the second mounting hole61.

The first mounting hole64has a diameter large enough to accommodate the first regulating valve28, and accommodates the first regulating valve28inserted from the opening in the upper surface of the upper housing50. A lower end part of the first mounting hole64has an opening of a first air outlet63. The first air outlet63extends toward the third mounting hole54and communicates with a spool sliding portion54bof the third mounting hole54at the third connection portions20c. Moreover, a side part of the first mounting hole64has an opening of a second air outlet65. The first mounting hole64communicates with the air outlet48avia the second air outlet65.

The first regulating valve28is configured by a needle valve with a check valve116, and includes a needle115and a tubular portion117in which the needle115is fitted. The check valve116is provided for an outer circumferential part of the tubular portion117. The check valve116and the tubular portion117are disposed between the first air outlet63and the second air outlet65. The check valve116is configured to check air flowing upward in the first mounting hole64and to allow the passage of air flowing downward. That is, the air flowing downward in the first mounting hole64passes through the check valve116while the flow rate of air flowing in the opposite direction is regulated by the needle valve. The needle valve is configured to control the flow rate of air when the channel is narrowed by the needle115moving downward and fitted in the tubular portion117, and is configured to increase the flow rate of air when the channel between the needle115and the tubular portion117is widened by the needle115moving upward.

The first regulating valve28further includes a needle holding portion114accommodating the needle115such that the needle115can move vertically, a control knob111, a link portion112transferring the rotational force of the control knob111to the needle115, a graduated portion113indicating the position of the needle115, and a case body110covering the link portion112and the graduated portion113. The needle holding portion114moves the needle115vertically through a screw mechanism. A lower end part of the link portion112is linked with the needle115, and an upper end part of the link portion112is linked with the control knob111. The link portion112rotates in an integrated manner with the control knob111to transfer the rotational force of the control knob111to the needle115. The graduated portion113is a member linked with an outer circumferential part of the link portion112. The graduated portion113indicates the degree of opening of the needle115and is joined to the outer circumferential part of the link portion112.

The graduated portion113and the link portion112are covered with the case body110. As illustrated inFIG. 4, a U-shaped window portion110cis formed by partially cutting off an outer circumferential part of the case body110, and the markings of the graduated portion113can be visually checked through the window portion110c.

As illustrated inFIG. 3, the second mounting hole61has a diameter large enough to accommodate the second regulating valve26. A lower end part of the second mounting hole61has an opening of the first introduction path21. The first introduction path21extends downward to the back of the drawing sheet to communicate with the second channel16. Moreover, a pilot air channel60extends from a side part of the second mounting hole61in the X direction to communicate with a piston chamber54aof the third mounting hole54.

The second regulating valve26is comprised of a needle valve with the check valve116having a similar structure as the first regulating valve28. In the second regulating valve26, the same reference numerals and symbols are used for components similar to those in the first regulating valve28, and the detailed descriptions will be omitted. The check valve116and the needle valve of the second regulating valve26are disposed between the first introduction path21and the pilot air channel60of the second mounting hole61. In the second regulating valve26, the check valve116constitutes the check valve122inFIG. 1checking air flowing from the first introduction path21to the pilot air channel60and allowing the passage of air flowing in the opposite direction.

The third mounting hole54inFIG. 3includes the piston chamber54aand the spool sliding portion54bprovided for the upper housing50and a spool accommodating hole54cprovided for the lower housing52. The piston chamber54a, the spool sliding portion54b, and the spool accommodating hole54care arranged in this order from top to bottom. The piston chamber54ais an empty room having an inner diameter larger than an outer diameter of a spool70(described later), and an upper end part of the piston chamber54ais sealed with an end cap58. Moreover, a side part of the piston chamber54ahas an opening of the pilot air channel60. The drive piston22is disposed in the piston chamber54abetween the pilot air channel60and the spool sliding portion54b. The drive piston22airtightly partitions the piston chamber54ainto an area communicating with the pilot air channel60and an area adjacent to the spool sliding portion54b. The drive piston22is configured to be displaced downward by the pressure of pilot air flowing from the pilot air channel60.

The spool sliding portion54bhas an inner diameter substantially identical to the outer diameter of the spool70, and the spool70is disposed inside of the spool sliding portion54b. The spool70is disposed inside the spool sliding portion54band the spool accommodating hole54c.

The spool accommodating hole54cis an empty room with a substantially columnar shape, and a lower end part of the spool accommodating hole54cis sealed with an end member79. The spool accommodating hole54chas an inner diameter larger than the outer diameter of the spool70, and a spool guide80is installed inside of the spool accommodating hole54c. The spool guide80is a substantially cylindrical member having a slide hole80awith an inner diameter substantially identical to the diameter of the spool70, and the spool70is fitted in the slide hole80a. The biasing member24such as a coil spring is disposed at the end member79of the spool accommodating hole54c. The biasing member24is in contact with a lower end part of the spool70and biases the spool70toward the end cap58.

A side part of the spool accommodating hole54chas an opening of the channel14aextending from the first connection port12a. The spool guide80includes the second connection portions20bradially passing through the spool guide80in the vicinity of the channel14a. The interior of the spool guide80communicates with the channel14avia the second connection portions20b. Moreover, a side part of the spool accommodating hole54cabove the channel14ahas an opening of the channel14bextending from the first cylinder port12c. The spool guide80includes the first connection portions20aradially passing through the spool guide80in the vicinity of the channel14b. The interior of the spool guide80communicates with the channel14bvia the first connection portions20a.

Moreover, the spool guide80includes a first narrowed portion81aformed between the first connection portions20aand the second connection portions20band a second narrowed portion81bdisposed between the first connection portions20aand the third connection portions20c. When the spool70is biased by the biasing member24and disposed at a first position, the second narrowed portion81bis in firm contact with a first partition wall74of the spool70to airtightly isolate the first connection portions20aand the third connection portions20cfrom each other. Moreover, when the spool70is pushed by the drive piston22and displaced downward to a second position (seeFIG. 7), the first narrowed portion81acomes into firm contact with a second partition wall76of the spool70to airtightly isolate the first connection portions20aand the second connection portions20bfrom each other.

The spool70has a first recess71, a second recess73, and a third recess75created in outer circumferential parts of the spool70from top to bottom. Moreover, the spool70has an intra-spool channel72ainside of the spool70to cause the first recess71and the second recess73to communicate with each other. The first recess71is created at a position to communicate with the first air outlet63when the spool70is at the second position. The second recess73is created at a position to communicate with the first connection portions20awhen the spool70is at the second position. The intra-spool channel72aextends along the central axis of the spool70in the axial direction, and the upper end of the intra-spool channel72ais sealed with a sealing portion68. The upper end of the intra-spool channel72acommunicates with the first recess71through holes radially passing through the spool70at the position of the first recess71, and the lower end of the intra-spool channel72acommunicates with the second recess73through holes radially passing through the spool70at the position of the second recess73. That is, when the spool70is at the second position, the first connection portions20aand the first air outlet63communicate with each other via the first recess71, the intra-spool channel72a, and the second recess73.

The third recess75is longer than the first narrowed portion81ain the axial direction, and is created at a position to communicate with the first connection portions20aand the second connection portions20bwhen the spool70is at the first position. That is, the third recess75causes the first connection portions20aand the second connection portions20bto communicate with each other when the spool70is at the first position. When the spool70is at the second position, the third recess75communicates only with the second connection portions20b.

A sliding portion72having an outer diameter substantially identical to the diameter of the spool sliding portion54bis formed between the first recess71and the second recess73of the spool70, and packings72band72care disposed on outer circumferential parts of the sliding portion72. The packings72band72cprevent air from leaking along the outer circumferential parts of the sliding portion72.

Moreover, the first partition wall74and the second partition wall76are formed between the second recess73and the third recess75. A packing74ais attached to the first partition wall74. When the spool70is at the first position, the first partition wall74is located at the second narrowed portion81b, and the packing74ais in firm contact with the second narrowed portion81bto airtightly isolate the second recess73and the first connection portions20afrom each other. Moreover, when the spool70is at the second position, the first partition wall74is separated from the second narrowed portion81b, and the second recess73and the first connection portions20acommunicate with each other. Moreover, a packing76ais attached to the second partition wall76. The second partition wall76is formed below the first partition wall74and is separated from the first narrowed portion81awhen the spool70is at the first position. When the spool70is at the second position, the second partition wall76is located inside the first narrowed portion81a, and the packing76ais in firm contact with the first narrowed portion81ato airtightly isolate the first connection portions20aand the second connection portions20bfrom each other.

The first connection port12ais disposed in one side part of the lower housing52and communicates with the second connection portions20bvia the channel14a. Moreover, the channel14ahas an opening of one end of the second introduction path31, and the second introduction path31extends to the fourth regulating valve36in the second flow rate adjustment section13B. A pipe from the operation switching valve40is connected to the first connection port12a.

The first cylinder port12cis disposed in another side part of the lower housing52and communicates with the first connection portions20avia the channel14b. The pipe14cextending from the rod-side port104of the air cylinder100is connected to the first cylinder port12c.

The flow controller12and the driving apparatus10according to this embodiment are configured as above. Operations thereof will now be described.

As illustrated inFIG. 5, during the working process where the piston rod108of the air cylinder100is pushed out, the operation switching valve40is displaced to the second position. This causes the high-pressure air supply source46to be connected to the second channel16and the air outlet48bto be connected to the first channel14. The first switching valve20and the second switching valve30are respectively biased by the biasing members24and34to the first positions. The high-pressure air in the second channel16flows in the channel16aof the flow controller12as indicated by arrows A1and A2. The high-pressure air then flows into the cylinder chamber100aof the air cylinder100via the second connection portion30band the first connection portion30aof the second switching valve30. The speed controller44on the pipe16cof the second channel16allows the passage of air flowing to the air cylinder100without regulating the flow rate of the air.

The air in the rod-side part of the cylinder chamber100aof the air cylinder100is exhausted from the rod-side port104as the piston106moves. The air exhausted from the air cylinder100is exhausted from the air outlet48bvia the speed controller42and the first switching valve20provided for the first channel14. Since the meter-out speed controller42regulates the flow rate of air exhausted from the air cylinder100, the piston rod108operates at a drive speed (first speed) according to the degree of opening of the speed controller42.

Moreover, during the working process, pilot air flows into the drive piston22of the first switching valve20via the first introduction path21and the second regulating valve26as indicated by an arrow A3inFIG. 5. The pilot air flowing in the first introduction path21is regulated by the second regulating valve26. As a result, the pressure of the pilot air in the piston chamber54agradually increases with the passage of time t as illustrated inFIG. 6. The first switching valve20is kept at the first position to which the first switching valve20is biased by the biasing member24until the piston106of the air cylinder100approaches a predetermined position in the vicinity of the stroke end. The pushing force of the drive piston22of the first switching valve20exceeds the biasing force of the biasing member24at a point tmin time when the pressure of the pilot air in the piston chamber54abecomes greater than a predetermined pressure Pth. As a result, the first switching valve20is displaced to the second position.

As illustrated inFIG. 7, when the first switching valve20is at the second position, the spool70is located at the lower end. This causes the first connection portions20aand the third connection portions20cto communicate with each other. As indicated by a broken line arrow B5inFIG. 8, the exhaust air in the channel14bis exhausted from the air outlet48avia the first regulating valve28. The first regulating valve28further reduces the flow rate of exhaust air exhausted from the air cylinder100more than the speed controller42reduces the flow rate, to reduce the moving speed of the piston106in the vicinity of the stroke end of the air cylinder100to the second speed that is slower than the first speed. This can reduce impact on the air cylinder100at the stroke end.

Subsequently, the retracting process where the piston rod108of the air cylinder100is drawn in follows. As illustrated inFIG. 9, during the retracting process, the operation switching valve40is displaced to the first position to cause the high-pressure air supply source46to communicate with the first channel14, and cause the air outlet48bto communicate with the second channel16. At this moment, the second channel16is exposed to the atmosphere via the air outlet48b, and thus the pilot air in the first switching valve20is exhausted through the first introduction path21and the check valve122of the second regulating valve26. The first switching valve20then returns to the first position by the biasing force of the biasing member24. This causes the first connection portions20aand the second connection portions20bto communicate with each other. Subsequently, the high-pressure air of the high-pressure air supply source46is supplied to the rod-side part of the cylinder chamber100aof the air cylinder100via the first channel14.

During the retracting process, the flow rate of exhaust air exhausted from the air cylinder100is regulated by the speed controller44provided for the second channel16. As a result, the piston rod108is drawn in at a predetermined speed (third speed) according to the degree of opening of the speed controller44.

Moreover, during the retracting process, pilot air is supplied to the second switching valve30from the first channel14via the second introduction path31. The pressure of the pilot air gradually increases at a predetermined speed according to the degree of opening of the fourth regulating valve36provided for the second introduction path31. The pushing force of the drive piston32of the second switching valve30exceeds the biasing force of the biasing member34at a point in time when the pressure of the pilot air reaches a predetermined pressure, and thereby the second switching valve30is displaced to the second position. That is, the second switching valve30is displaced to the second position at a predetermined point in time when the piston106of the air cylinder100reaches the vicinity of the stroke end.

As a result, as illustrated inFIG. 10, the first connection portion30aand the third connection portion30cof the second switching valve30communicate with each other, and the exhaust air from the air cylinder100flows toward the third regulating valve38as indicated by an arrow D3. The air is then exhausted from the air outlet48avia the third regulating valve38. The third regulating valve38causes the piston106to be displaced at the fourth speed slower than the third speed by further reducing the flow rate of exhaust air more than the speed controller44reduces the flow rate. This controls the operating speed of the piston106at the stroke end during the retracting process, resulting in less impact on the air cylinder100.

The flow controller12and the driving apparatus10according to this embodiment described above produce the following advantageous effects.

The flow controller12includes the first switching valve20configured to be displaced from the first position to the second position under the effect of pilot air, cause the rod-side port104of the air cylinder100to communicate with the first channel14at the first position, and cause the rod-side port104of the air cylinder100to communicate with the air outlet48avia the first regulating valve28at the second position, the first introduction path21configured to guide the pilot air from the second channel16to the first switching valve20, and the second regulating valve26provided for the first introduction path21and configured to adjust timing of displacement of the first switching valve20by regulating the flow rate of the pilot air.

According to the above-described structure, the pilot air is supplied to the second regulating valve26from the second channel16different from the channel provided with the first regulating valve28and the speed controller42. This facilitates adjustment to operation of the flow controller12since the operation of the second regulating valve26is not affected by the degrees of opening of the first regulating valve28and the speed controller42.

In the flow controller12, the first regulating valve28may comprise a throttle valve configured to regulate the flow rate of air exhausted from the rod-side port104of the air cylinder100. This controls the operating speed in the vicinity of the stroke end of the air cylinder100, resulting in less impact at the stroke end.

The flow controller12may further include the second switching valve30configured to be displaced from the first position to the second position under the effect of pilot air, cause the head-side port102of the air cylinder100to communicate with the second channel16at the first position, and cause the head-side port102of the air cylinder100to communicate with the air outlet48avia the third regulating valve38at the second position, the second introduction path31configured to guide the pilot air from the first channel14to the second switching valve30, and the fourth regulating valve36provided for the second introduction path31and configured to adjust timing of displacement of the second switching valve30by regulating the flow rate of the pilot air.

According to the above-described structure, the operating speed at the stroke end can also be changed gradually during the retracting process of the air cylinder100.

In the flow controller12, the third regulating valve38may comprise a throttle valve reducing the flow rate of air exhausted from the head-side port102of the air cylinder100. Thus, the operating speed in the vicinity of the stroke ends can be controlled during both the working process and the retracting process, and the impact at the stroke ends can be reduced.

In the flow controller12, each of the first switching valve20and the second switching valve30may be displaced from the first position to the second position at a point in time when the pressure of the pilot air reaches or exceeds a predetermined value. Since the switching timing can be adjusted using the meter-in second regulating valve26and the meter-in fourth regulating valve36, the flow controller12can be easily adjusted.

In the flow controller12, each of the second regulating valve26and the fourth regulating valve36may comprise an variable throttle valve and may be provided with a graduated portion113indicating the degree of opening of the variable throttle valve. This facilitates adjustment to operation timing of the second regulating valve26and the fourth regulating valve36.

In the flow controller12, each of the first regulating valve28and the third regulating valve38may comprise an variable throttle valve or a fixed throttle valve.

In the flow controller12, each of the first switching valve20and the second switching valve30may comprise a spool valve. This enables reliable switching operations using pilot air. In addition, sufficient cross-sectional areas can be secured to operate the air cylinder100at high speed.

The driving apparatus10of the air cylinder100according to this embodiment includes the flow controller12, the high-pressure air supply source46configured to supply high-pressure air to the air cylinder100via the first channel14or the second channel16, and the air outlet48bconfigured to exhaust the air from the air cylinder100via the first channel14or the second channel16. Thus, adjustment of the driving apparatus10can be simplified due to the flow controller12.

The driving apparatus10may further include the operation switching valve40configured to switch between a first connection state where the first channel14communicates with the high-pressure air supply source46while the second channel16communicates with the air outlet48band a second connection state where the second channel16communicates with the high-pressure air supply source46while the first channel14communicates with the air outlet48b.

The driving apparatus10may further includes the speed controller42(or44) configured to reduce the flow rate of air in the first channel14and the second channel16. Thus, the operating speed of the air cylinder100during the normal stroke before the first regulating valve28and the third regulating valve38regulate the operating speed, can be adjusted using the speed controllers42and44.

The present invention has been described by taking a preferred embodiment as an example. However, the present invention is not limited in particular to the above-described embodiment, and various modifications can be made thereto without departing from the scope of the present invention as a matter of course.