Patent Description:
Conventionally, a shock absorbing mechanism has been used in which a cushioning material made of a soft resin such as rubber or urethane or the like, or an oil damper or the like is attached to an end part of an air cylinder, to thereby cushion an impact at a stroke end. However, such a shock absorbing mechanism that mechanically mitigates shocks in the cylinder is limited in terms of the number of operations it can perform, and requires regular maintenance.

In order to resolve such incompatibility, in <CIT>, a speed controller (flow rate controller) is disclosed in which, by throttling the exhaust air that is discharged from the air cylinder in the vicinity of a stroke end, an operating speed of the air cylinder is reduced.

Post-published <CIT> discloses 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.

In such a conventional flow rate controller, the pilot air is gradually discharged through the throttle valve, and when the pilot pressure falls below a predetermined value, the switching valve performs a switching operation to throttle the exhaust air. However, it has been determined that when the pressure acting on the throttle valve falls below a predetermined pressure, the flow of the pilot air passing through the throttle valve may rapidly decrease, and the timing of the switching operation becomes unstable.

Therefore, an aspect of the present invention has the object of providing a flow rate controller, which is capable of stabilizing a timing of a switching operation, and a drive device equipped with such a flow rate controller.

The problem is solved by a flow rate controller according to claim <NUM>.

Another aspect of the present invention is characterized by a drive device according to claim <NUM>.

In accordance with the flow rate controller and the drive device comprising the same according to the above-described aspects, it is possible to stabilize the timing of the switching operation.

Hereinafter, a preferred embodiment of the present invention will be presented and described in detail below with reference to the accompanying drawings.

As shown in <FIG>, an air cylinder <NUM> is a double acting cylinder that is used in an automated equipment line or the like. The air cylinder <NUM> is equipped with a cylindrical cylinder tube <NUM>, a head cover <NUM> that seals a head side end part of the cylinder tube <NUM>, and a rod cover <NUM> that seals a rod side end part of the cylinder tube <NUM>. The cylinder tube <NUM>, the head cover <NUM>, and the rod cover <NUM> are tightened and connected in an axial direction by a plurality of connecting rods <NUM> and fixing bolts <NUM>.

In the interior of the cylinder tube <NUM>, as shown in <FIG>, there are provided a piston <NUM> that partitions a cylinder chamber <NUM>, and a piston rod <NUM> connected to the piston <NUM>. A head side port 76a is provided in a head side pressure chamber 18a on a head side of the piston <NUM>, and a rod side port 78a is provided in a rod side pressure chamber 18b on a rod side of the piston <NUM>. As shown in <FIG>, the head side port 76a is provided in the head cover <NUM>, and the rod side port 78a is provided in the rod cover <NUM>.

As shown in <FIG>, the air cylinder <NUM> is driven by a drive device <NUM>, which includes a head side flow rate controller <NUM> and a rod side flow rate controller <NUM>, an operation switching valve <NUM>, and a high pressure air supply source <NUM>. As shown in <FIG>, the head side flow rate controller <NUM> is connected via a head side pipe 20A to the head side port 76a of the air cylinder <NUM>, and the rod side flow rate controller <NUM> is connected via a rod side pipe 20B to the rod side port 78a. The head side pipe 20A and the rod side pipe 20B are included in a cylinder flow path <NUM> that allows the air cylinder <NUM> and the flow rate controller <NUM> to communicate with each other, and introduction of high pressure air into the air cylinder <NUM> and discharging of air from the air cylinder <NUM> are carried out via the cylinder flow path <NUM>.

As shown in <FIG>, the head side flow rate controller <NUM> includes a main flow path <NUM> connected to the cylinder flow path <NUM>, an auxiliary flow path <NUM> disposed in parallel with the main flow path <NUM>, and a bypass flow path <NUM> that connects the main flow path <NUM> and the cylinder flow path <NUM>. A switching valve <NUM> is connected between the main flow path <NUM> and the auxiliary flow path <NUM>, and the cylinder flow path <NUM>. The switching valve <NUM> is a so-called three-way valve, and is connected to the cylinder flow path <NUM>, the main flow path <NUM>, and the auxiliary flow path <NUM>. A third throttle valve <NUM> for adjusting the flow rate of the air is provided in the main flow path <NUM>. The third throttle valve <NUM>, by variably regulating the flow rate of the exhaust air that flows through the main flow path <NUM>, makes it possible to adjust the operating speed of the air cylinder <NUM>.

On the other hand, a first throttle valve <NUM>, which variably regulates the flow rate of the exhaust air flowing through the auxiliary flow path <NUM>, is provided in the auxiliary flow path <NUM>. The first throttle valve <NUM> is configured to throttle the flow rate of the exhaust air more strongly than the third throttle valve <NUM> of the main flow path <NUM>. An exhaust port 24a is connected to a downstream side of the first throttle valve <NUM>, and the exhaust air that has passed through the first throttle valve <NUM> is discharged from the exhaust port 24a.

One end of the bypass flow path <NUM> is connected to the main flow path <NUM> between the third throttle valve <NUM> and a valve port 12a, whereas the other end thereof is connected to the cylinder flow path <NUM>, to connect the main flow path <NUM> and the cylinder flow path <NUM> while bypassing the third throttle valve <NUM> and the switching valve <NUM>. The bypass flow path <NUM> is provided with a shuttle valve <NUM>, which includes a first inlet 32a, a second inlet 32b, and an outlet 32c. A first portion 28a of the bypass flow path <NUM> is connected to the first inlet 32a of the shuttle valve <NUM>, a second portion 28b of the bypass flow path <NUM> is connected to the outlet 32c, and the switching valve <NUM> is connected via a pilot air adjustment part <NUM> to the second inlet 32b.

When a pressure in the main flow path <NUM> becomes higher than a pressure in the cylinder flow path <NUM>, the shuttle valve <NUM> closes the second inlet 32b and allows the first inlet 32a and the outlet 32c to communicate with each other to introduce the high pressure air of the main flow path <NUM> into the cylinder flow path <NUM> through the bypass flow path <NUM>. Further, when the pressure in the main flow path <NUM> becomes lower than the pressure in the cylinder flow path <NUM>, the shuttle valve <NUM> closes the first inlet 32a and allows the second inlet 32b and the outlet 32c to communicate with each other to guide the exhaust air in the cylinder flow path <NUM> to the pilot air adjustment part <NUM> as pilot air.

The pilot air adjustment part <NUM> is disposed between the second inlet 32b of the shuttle valve <NUM> and the switching valve <NUM>. The pilot air adjustment part <NUM> includes a second throttle valve 31a, and a check valve 31b which is connected in parallel with the second throttle valve 31a. A downstream side of the second throttle valve 31a and the check valve 31b is connected to a later-described piston member <NUM> (see <FIG>) of the switching valve <NUM>. The pilot air that has passed through the second throttle valve 31a drives the switching valve <NUM>, and switches the switching valve <NUM> from a first position, in which the exhaust air flows from the cylinder flow path <NUM> to the main flow path <NUM>, to a second position, in which the exhaust air flows from the cylinder flow path <NUM> to the auxiliary flow path <NUM> (refer to the switching valve <NUM> on the left side of <FIG>).

The check valve 31b is connected in a direction that allows passage of air flowing from the switching valve <NUM> to the shuttle valve <NUM>. When the pressure of the exhaust air in the cylinder flow path <NUM> decreases, the check valve 31b causes the pilot air in the switching valve <NUM> to be discharged to the cylinder flow path <NUM> side. Accompanying discharging of the pilot air, the switching valve <NUM> is returned from the second position to the first position by the elastic force of a return spring 26a of the switching valve <NUM>.

Since the rod side flow rate controller <NUM>, which is connected to the rod side pipe 20B, is configured in substantially the same manner as the head side flow rate controller <NUM>, constituent elements thereof which are the same as the constituent elements of the head side flow rate controller <NUM> are designated by the same reference numerals, and detailed description thereof is omitted.

Next, a description will be given concerning the configuration of the operation switching valve <NUM> that is connected to the head side flow rate controller <NUM> and the rod side flow rate controller <NUM>. One end of a third pipe 27A is connected to the valve port 12a of the head side flow rate controller <NUM>, and one end of a fourth pipe 27B is connected to the valve port 12a of the rod side flow rate controller <NUM>. The operation switching valve <NUM> is connected to another end of the third pipe 27A and another end of the fourth pipe 27B.

The operation switching valve <NUM> is a <NUM>-port valve that electrically switches a connection destination of the high pressure air, and includes first through fifth ports 34a to 34e. The first port 34a is connected to the third pipe 27A, and the second port 34b is connected to the fourth pipe 27B. The third port 34c and the fifth port 34e are connected to exhaust ports <NUM>, and the fourth port 34d is connected to the high pressure air supply source <NUM>.

At a first position shown in <FIG>, the operation switching valve <NUM> allows the first port 34a and the fourth port 34d to communicate with each other, and allows the second port 34b and the fifth port 34e to communicate with each other. In this manner, the operation switching valve <NUM> allows the high pressure air supply source <NUM> to communicate with the head side port 76a, and allows the exhaust port <NUM> to communicate with the rod side port 78a.

Further, at a second position, the operation switching valve <NUM> allows the first port 34a and the third port 34c to communicate with each other, and allows the second port 34b to communicate with the fourth port 34d. In this manner, the operation switching valve <NUM> allows the high pressure air supply source <NUM> to communicate with the rod side port 78a, and allows the exhaust port <NUM> to communicate with the head side port 76a.

A circuit configuration of the drive device <NUM> according to the present embodiment is configured in the manner described above. A description will be given below concerning a specific structure of the flow rate controller <NUM>.

As shown in <FIG>, the flow rate controller <NUM> includes a flat box-shaped housing <NUM>. The housing <NUM> has, incorporated therein, the cylinder flow path <NUM>, the main flow path <NUM>, the auxiliary flow path <NUM>, the bypass flow path <NUM>, the first throttle valve <NUM>, the switching valve <NUM>, the pilot air adjustment part <NUM>, the third throttle valve <NUM>, and the shuttle valve <NUM>. A plurality of holes are formed on an upper surface 40a of the housing <NUM>, and the first throttle valve <NUM>, the third throttle valve <NUM>, the pilot air adjustment part <NUM>, and the shuttle valve <NUM> are inserted into such holes. As shown in <FIG>, the third throttle valve <NUM> is made up from a needle valve provided midway along an internal flow path 50a (main flow path <NUM>) connecting the valve port 12a and the switching valve <NUM>, and is capable of variably adjusting the flow rate by an adjustment screw on an upper end thereof being rotated.

As shown in <FIG>, the pilot air adjustment part <NUM> is constituted by a check valve equipped throttle valve <NUM> in which the check valve 31b and the second throttle valve 31a are formed integrally. By rotating a screw mechanism <NUM>, the flow rate of the second throttle valve 31a is capable of being changed. Further, the check valve 31b is equipped with an elastic valve member <NUM>, and allows passage of the air flowing from an internal flow path 30a to an internal flow path 30b, and prevents the flow of the air in the opposite direction.

The shuttle valve <NUM> includes a shuttle valve installation hole <NUM> having an inclined portion 61a, a distal end of which is reduced in diameter in a tapered shape. The first inlet 32a of the shuttle valve <NUM> is formed on the inclined portion 61a, on a side portion of the shuttle valve installation hole <NUM>. Further, the second inlet 32b of the shuttle valve <NUM> is formed at a position higher than the first inlet 32a, on a side portion of the shuttle valve installation hole <NUM>. Further, the outlet 32c of the shuttle valve <NUM> is formed at a lower end part of the shuttle valve installation hole <NUM>.

The shuttle valve <NUM> further includes a flow path member <NUM> that is inserted into the shuttle valve installation hole <NUM>, and a valve element <NUM> disposed between the flow path member <NUM> and the inclined portion 61a. The flow path member <NUM> includes, at an upper end thereof, a sealing portion <NUM> formed with an inner diameter that is substantially the same as the inner diameter of the shuttle valve installation hole <NUM>. The sealing portion <NUM> seals an upper end part of the shuttle valve installation hole <NUM>. A tube portion <NUM> extends from the sealing portion <NUM> of the flow path member <NUM> toward the lower end of the shuttle valve installation hole <NUM>.

The tube portion <NUM> is a tubular member having a diameter smaller than the inner diameter of the shuttle valve installation hole <NUM>, and a lower end part (distal end part) of the tube portion <NUM> opens in the vicinity of the outlet 32c, and further, a ventilation hole <NUM>, which penetrates through the tube portion <NUM> in a radial direction, is formed in the vicinity of a proximal end part of the tube portion <NUM>. Further, a partition member <NUM> and a gasket 65a, which are in close contact with the shuttle valve installation hole <NUM>, are provided in an outer peripheral portion of the tube portion <NUM>, at a portion between the outlet 32c and the second inlet 32b. The partition member <NUM> and the gasket 65a airtightly separate the second inlet 32b and the outlet 32c on an outer side of the tube portion <NUM>.

The valve element <NUM> is made up from an elastic member, is formed in a substantially conical plate shape that is convex downward, and has a substantially V-shaped cross section. A lower end side of the valve element <NUM> has an inclined surface that can be brought into close contact with the inclined portion 61a. A conically-shaped protruding part <NUM>, which can be inserted into the tube portion <NUM>, is formed at an upper end central portion of the valve element <NUM>. At the position shown in <FIG>, the lower end side of the valve element <NUM> is in close contact with the inclined portion 61a, and airtightly seals the first inlet 32a and the outlet 32c while allowing the second inlet 32b and the outlet 32c to communicate with each other. When a pressure on the first inlet 32a side increases, the valve element <NUM> rises, whereby the protruding part <NUM> is inserted into the tube portion <NUM> and the valve element <NUM> covers the tube portion <NUM>. In this state, the valve element <NUM> closes the inner side of the tube portion <NUM> to block communication between the second inlet 32b and the outlet 32c, and at the same time, the outer peripheral portion of the valve element <NUM> is elastically deformed along the flow direction of the air, whereby the first inlet 32a and the outlet 32c are allowed to communicate with each other. More specifically, when the valve element <NUM> is displaced upward, the shuttle valve <NUM> places the first portion 28a and the second portion 28b of the bypass flow path <NUM> in communication.

The first inlet 32a of the shuttle valve <NUM> communicates with the valve port 12a (main flow path <NUM>) shown in <FIG> through the first portion 28a of the bypass flow path <NUM>. Further, as shown in <FIG>, the second inlet 32b of the shuttle valve <NUM> communicates with the adjacent pilot air adjustment part <NUM> through the internal flow path 30b. Furthermore, the outlet 32c communicates with a cylinder port 12b (cylinder flow path <NUM>) through the second portion 28b of the bypass flow path <NUM>.

On the other hand, as shown in <FIG>, the first throttle valve <NUM> and the exhaust port 24a are configured in the form of an exhaust throttle valve in which these members are formed integrally, and the exhaust air is discharged therethrough from the upper surface 40a side shown in the drawing. By rotating a needle adjustment screw that is exposed on the upper surface 40a, the flow rate of the first throttle valve <NUM> can be changed.

The cylinder port 12b for connecting the head side pipe 20A or the rod side pipe 20B on the air cylinder <NUM> side is formed on a rear surface 40d of the housing <NUM>. The valve port 12a for connecting the third pipe 27A or the fourth pipe 27B is formed on a front surface 40b (see <FIG>) of the housing <NUM>. Further, a spool guide hole <NUM> is formed so as to penetrate from one side surface 40c to another side surface 40e of the housing <NUM>. The switching valve <NUM> is disposed in the spool guide hole <NUM>.

As shown in <FIG>, the switching valve <NUM> is configured in the form of a spool valve equipped with the spool guide hole <NUM>, and a spool <NUM> that is accommodated in the spool guide hole <NUM>. The spool guide hole <NUM> includes a spool guide portion 42a formed with a relatively small inner diameter, and a piston accommodating portion 42b formed with an inner diameter larger than that of the spool guide portion 42a. The spool guide hole <NUM> is sealed by a cap <NUM> that closes an end part on the spool guide portion 42a side, and a cap <NUM> that closes an end part on the piston accommodating portion 42b side. The cap <NUM> and the cap <NUM> are each fixed in the spool guide hole <NUM> by retaining clips 58a.

A first communication groove <NUM>, a second communication groove <NUM>, and a third communication groove <NUM>, which are formed by expanding the entire circumference of the inner diameter in groove-like shapes, are formed in the spool guide portion 42a. The first communication groove <NUM> is formed closest to the cap <NUM>, and communicates with the valve port 12a via the internal flow path 50a. The second communication groove <NUM> is a groove that is formed at a portion closer to the piston member <NUM>, and communicates with the first throttle valve <NUM> and the exhaust port 24a via an internal flow path 52a. The third communication groove <NUM> is a groove that is formed between the first communication groove <NUM> and the second communication groove <NUM>, and communicates with the cylinder port 12b via an internal flow path 54a.

The piston accommodating portion 42b is formed with a diameter larger than that of the spool guide portion 42a, and a piston chamber <NUM> is formed in the interior thereof. The piston chamber <NUM> accommodates the piston member <NUM> of the spool <NUM>. The return spring 26a that biases the piston member <NUM> toward the side surface 40c side and returns the piston member <NUM> to the first position is provided on the side surface 40e side of the piston chamber <NUM>. The internal flow path 30a opens on the side surface 40c side of the piston chamber <NUM>. The internal flow path 30a communicates with the pilot air adjustment part <NUM>.

The spool <NUM> is arranged to be capable of sliding in the spool guide hole <NUM> in an axial direction perpendicular to the side surfaces 40c and 40e. On the side surface 40e side of the spool <NUM>, there is provided a spool portion 46a that is inserted inside the spool guide hole <NUM>, and on the side surface 40c side of the spool <NUM>, there is provided the piston member <NUM> that drives the spool <NUM>. The piston member <NUM> has a diameter that is larger than that of the spool portion 46a, and is accommodated in the piston chamber <NUM>. A packing <NUM> is installed on an outer peripheral portion of the piston member <NUM>, and the packing <NUM> partitions the piston chamber <NUM> in an airtight manner into a vacant chamber on the side surface 40c side, and a vacant chamber on the side surface 40e side.

The spool portion 46a includes guide end parts 46e and 46f at both ends thereof in the axial direction. The guide end parts 46e and 46f are formed with an outer diameter that is slightly smaller than the inner diameter of the spool guide portion 42a, and guide the movement of the spool <NUM> in the axial direction. Packings <NUM> are provided respectively on the guide end parts 46e and 46f, in order to prevent air from leaking along the axial direction. Between the above-described guide end parts 46e and 46f, there are formed a first sealing wall 46c, a second sealing wall 46d, and recesses 47a, 47b, and 47c.

The first sealing wall 46c and the second sealing wall 46d are formed with outer diameters that are slightly smaller than the inner diameter of the spool guide portion 42a, and include the packings <NUM> on the outer peripheral portion thereof. At the first position shown in <FIG>, the first sealing wall 46c is formed at a position in close contact with the inner wall of the spool guide portion 42a between the second communication groove <NUM> and the third communication groove <NUM>, and blocks communication between the second communication groove <NUM> and the third communication groove <NUM>. On the other hand, the second sealing wall 46d is provided so as to be separated away from the first sealing wall 46c toward the side surface 40e side, and at the first position, is positioned inside the third communication groove <NUM>, and allows communication between the third communication groove <NUM> and the first communication groove <NUM>.

At the second position of the spool <NUM>, the second sealing wall 46d is in close contact with the inner peripheral surface of the spool guide portion 42a between the third communication groove <NUM> and the first communication groove <NUM>, and blocks communication between the third communication groove <NUM> and the first communication groove <NUM>. Moreover, the first sealing wall 46c is positioned inside the third communication groove <NUM> at the second position, and allows communication between the third communication groove <NUM> and the second communication groove <NUM>.

The recess 47a is formed between the second sealing wall 46d and the guide end part 46e, and at the first position of the spool <NUM>, forms a flow path having a large cross-sectional area in order to facilitate the passage of air between the first communication groove <NUM> and the third communication groove <NUM>. The recess 47b is formed between the first sealing wall 46c and the second sealing wall 46d. Further, the recess 47c is formed between the first sealing wall 46c and the guide end part 46f, and at the second position of the spool <NUM>, forms a flow path having a large cross-sectional area between the second communication groove <NUM> and the third communication groove <NUM>.

The specific structure of the flow rate controller <NUM> is configured in the manner described above. Hereinafter, a description will be given concerning actions of the drive device <NUM> of the present embodiment together with operations thereof. In this instance, with reference to <FIG> and <FIG>, a description will be given as an example of an operating stroke for moving the piston <NUM> toward the rod side port 78a.

As shown in <FIG>, in the operating stroke, the operation switching valve <NUM> is switched to the first position, and the high pressure air supply source <NUM> communicates with the third pipe 27A. The high pressure air flows into the head side flow rate controller <NUM> through the valve port 12a. In the flow rate controller <NUM>, the high pressure air flows into the main flow path <NUM> and the bypass flow path <NUM>. The switching valve <NUM> is placed in the first position, which is an initial position, and as shown by the arrow A1, the high pressure air in the main flow path <NUM> flows into the cylinder flow path <NUM> through the switching valve <NUM>.

Further, in the bypass flow path <NUM>, the pressure in the first portion 28a becomes higher than the pressure in the second portion 28b. Therefore, the valve element <NUM> of the shuttle valve <NUM> shown in <FIG> is pushed upward toward an upper end side, whereby the first inlet 32a and the outlet 32c communicate with each other, and the first portion 28a and the second portion 28b of the bypass flow path <NUM> are placed in communication. Accordingly, as shown by the arrow A2 in <FIG>, the high pressure air flows into the cylinder flow path <NUM> via the bypass flow path <NUM>. Since there is no throttle valve in the bypass flow path <NUM>, the high pressure air is introduced in a free flowing manner into the head side port 76a of the air cylinder <NUM>.

On the other hand, the exhaust air, which is discharged from the rod side pressure chamber 18b, flows into the rod side flow rate controller <NUM> via the rod side pipe 20B. The exhaust air flows in from the cylinder port 12b of the flow rate controller <NUM>. The rod side switching valve <NUM> is in the first position, the cylinder flow path <NUM> and the main flow path <NUM> communicate with each other, and as shown by the arrow B1, the exhaust air is discharged from the exhaust port <NUM> through the main flow path <NUM>. At that time, the flow rate of the exhaust air is throttled by the third throttle valve <NUM>, and the operating speed of the piston <NUM> of the air cylinder <NUM> is regulated by the third throttle valve <NUM>. In this manner, the flow rate controller <NUM> constitutes a meter-out speed controller, which regulates the operating speed of the piston <NUM> by the exhaust air that is discharged from the air cylinder <NUM>.

Further, in the rod side flow rate controller <NUM>, as shown by the arrow P, a portion of the exhaust air flows into the second portion 28b of the bypass flow path <NUM>. At this time, in the shuttle valve <NUM>, as shown in <FIG>, the valve element <NUM> is biased downward, communication between the first inlet 32a and the outlet 32c is blocked, and the second inlet 32b and the outlet 32c communicate with each other. As shown in <FIG>, the exhaust air that has passed through the shuttle valve <NUM> passes through the pilot air adjustment part <NUM> as pilot air, and is supplied to the switching valve <NUM>. The flow rate of the pilot air is variably adjusted by the second throttle valve 31a.

Thereafter, accompanying movement of the piston <NUM>, the pressure of the pilot air in the rod side switching valve <NUM> gradually increases. Then, at a predetermined timing at which the piston <NUM> approaches the stroke end, the rod side switching valve <NUM> switches from the first position to the second position due to the pressure of the pilot air, against the elastic force of the return spring 26a.

As shown in <FIG>, at the second position of the rod side switching valve <NUM>, the cylinder flow path <NUM> and the auxiliary flow path <NUM> communicate with each other. The exhaust air from the air cylinder <NUM> flows as shown by the arrow B2, and while being regulated by the first throttle valve <NUM> of the auxiliary flow path <NUM>, is discharged from the exhaust port 24a. Since the flow rate of the first throttle valve <NUM> is less than the flow rate of the third throttle valve <NUM>, the flow rate of the exhaust air is strongly throttled at the timing at which the piston <NUM> approaches the stroke end, whereby the speed of the piston <NUM> decreases. Consequently, shocks in the air cylinder <NUM> when the piston <NUM> reaches the stroke end are mitigated.

When the piston <NUM> is stopped, inflowing of the exhaust air into the flow rate controller <NUM> on the rod side ceases, and the pilot air of the switching valve <NUM> is discharged to the cylinder flow path side through the check valve 31b of the pilot air adjustment part <NUM>. Then, the switching valve <NUM> is returned to the first position by the elastic force of the return spring 26a.

In accordance with the foregoing, the operating stroke of the drive device <NUM> of the air cylinder <NUM> comes to an end. Thereafter, by the operation switching valve <NUM> being switched from the first position to the second position, the return stroke is carried out. In the return stroke, the exhaust air flows to the head side flow rate controller <NUM>, and the high pressure air flows to the rod side flow rate controller <NUM>. The operations of the drive device <NUM> in the return stroke simply involve a switching of places in the operating stroke between the head side flow rate controller <NUM> and the rod side flow rate controller <NUM>, and since the operations in the return stroke and the operations in the operating stroke are basically the same, a description of such operations will be omitted.

The flow rate controller <NUM> and the drive device <NUM> of the present embodiment realize the following advantageous effects.

In the conventional flow rate controller, when the pressure of the pilot air in the switching valve falls below <NUM> MPa, a situation has occurred in which the flow rate of the pilot air passing through the throttle valve rapidly decreases. For this reason, release of the pilot air becomes impossible, and a problem occurs in that the switching valve cannot be switched at an intended timing.

In contrast thereto, the flow rate controller <NUM> according to the present embodiment comprises the cylinder flow path <NUM> for communicating with a port of the air cylinder <NUM>, the main flow path <NUM> configured to supply and discharge air to and from the cylinder flow path, the auxiliary flow path <NUM> disposed in parallel with the main flow path and including the first throttle valve <NUM> configured to throttle a flow rate of the air to a flow rate less than that in the main flow path, the switching valve <NUM> connected to the cylinder flow path, the main flow path, and the auxiliary flow path, and configured to be switched between the first position in which the cylinder flow path is allowed to communicate with the main flow path, and the second position in which the cylinder flow path is allowed to communicate with the auxiliary flow path, and the pilot air adjustment part <NUM> configured to guide a portion of exhaust air in the cylinder flow path to the switching valve as pilot air, wherein the pilot air adjustment part includes the second throttle valve 31a configured to regulate an inflowing speed at which the pilot air flows into the switching valve, and the switching valve is switched from the first position to the second position due to a rise in a pressure of the pilot air, wherein the bypass flow path <NUM> is configured to bypass the switching valve and connect the cylinder flow path and the main flow path, and the shuttle valve <NUM> includes the first inlet 32a, the second inlet 32b, and the outlet 32c, wherein the first portion 28a of the bypass flow path that communicates with the main flow path is connected to the first inlet, the second portion 28b of the bypass flow path that communicates with the cylinder flow path is connected to the outlet, and the pilot air adjustment part is connected to the second inlet, wherein, when a pressure in the main flow path becomes higher than a pressure in the cylinder flow path, the shuttle valve closes the second inlet to allow the first inlet and the outlet to communicate with each other, and when the pressure in the cylinder flow path becomes higher than the pressure in the main flow path, the shuttle valve closes the first inlet to allow the second inlet and the outlet to communicate with each other.

With the flow rate controller <NUM> according to the present embodiment, a portion of the exhaust air is used as pilot air, and the pilot air adjustment part <NUM> functions as a meter-in speed controller that regulates the pilot air flowing into the switching valve <NUM>. Therefore, a pressure that is greater than or equal to <NUM> MPa continuously acts on the second throttle valve 31a, and it is possible to prevent a decrease in the flow rate of the pilot air passing through the second throttle valve 31a. As a result, in the flow rate controller <NUM>, the timing at which the switching valve <NUM> is operated is stabilized.

Further, the flow rate controller <NUM> of the present embodiment is also effective when connected to an air cylinder having a shock absorbing structure such as an air cushion. In this case, the flow rate of the air can be throttled from a time before the shock absorbing structure operates, and the load acting on the shock absorbing structure can be reduced. Further, in the case of the air cylinder being operated at a high speed, it becomes difficult for a repulsive force of the shock absorbing structure such as the air cushion to be adjusted at the end of the stroke, and the piston tends to vibrate unintentionally and bound near the end of the stroke. In such a case, if the flow rate controller <NUM> is provided in the drive device <NUM>, the flow rate of the air can be throttled before the shock absorbing structure operates, whereby the shock absorbing structure operates smoothly, and the occurrence of bounding can be prevented.

In the above-described flow rate controller <NUM>, there is further provided the bypass flow path <NUM> that bypasses the switching valve <NUM> and connects the cylinder flow path <NUM> and the main flow path <NUM>, and the shuttle valve <NUM> provided between the bypass flow path <NUM> and the pilot air adjustment part <NUM>, wherein, in the case that the pressure in the main flow path <NUM> is higher than the pressure in the cylinder flow path <NUM>, the shuttle valve <NUM> allows the main flow path <NUM> and the cylinder flow path <NUM> to communicate with each other while blocking communication between the pilot air adjustment part <NUM> and the bypass flow path <NUM>, whereas in the case that the pressure in the cylinder flow path <NUM> is higher than the pressure in the main flow path <NUM>, the shuttle valve <NUM> allows the cylinder flow path <NUM> and the pilot air adjustment part <NUM> to communicate with each other while blocking communication between the main flow path <NUM> and the cylinder flow path <NUM>.

In accordance with these features, since the high pressure air is capable of flowing into the cylinder flow path <NUM> not only through the main flow path <NUM> but also through the bypass flow path <NUM>, responsiveness to high speed operation of the air cylinder <NUM> is facilitated.

In the above-described flow rate controller <NUM>, there may be included the third throttle valve <NUM> that regulates the flow rate of the air flowing in the main flow path <NUM>, and the bypass flow path <NUM> may bypass the switching valve <NUM> and the third throttle valve <NUM>, and connect the main flow path <NUM> and the cylinder flow path <NUM>. In this manner, by providing the third throttle valve <NUM>, the flow rate of the exhaust air flowing through the main flow path <NUM> can be regulated, and the operating speed of the piston <NUM> of the air cylinder <NUM> can be adjusted by the third throttle valve <NUM>. Further, since the bypass flow path <NUM> is provided so as to bypass the switching valve <NUM> and the third throttle valve <NUM>, the high pressure air is not regulated by the flow rate of the third throttle valve <NUM>, and responsiveness to high speed operation of the air cylinder <NUM> is therefore facilitated.

In the above-described flow rate controller <NUM>, there may further be provided the housing <NUM> that accommodates the switching valve <NUM>, the pilot air adjustment part <NUM>, the first throttle valve <NUM>, the bypass flow path <NUM>, and the shuttle valve <NUM>, wherein the housing <NUM> may include the valve port 12a communicating with the main flow path <NUM>, the exhaust port 24a communicating with the auxiliary flow path <NUM>, and the cylinder port 12b communicating with the cylinder flow path <NUM>. In accordance with the above-described configuration, main portions of the flow rate controller <NUM> can be provided integrally within the housing <NUM>. Further, the flow rate controller <NUM> can be attached to the air cylinder <NUM> merely by connecting the pipes to the valve port 12a and the cylinder port 12b.

In the above-described flow rate controller <NUM>, the switching valve <NUM> may include the spool guide hole <NUM> including the first communication groove <NUM> communicating with the valve port 12a, the second communication groove <NUM> communicating with the first throttle valve <NUM>, and the third communication groove <NUM> communicating with the cylinder port 12b, the spool <NUM> disposed in the spool guide hole <NUM> slidably along the axial direction, and including the first guide end part 46e and the second guide end part 46f at both ends thereof in the axial direction, the first sealing wall 46c for blocking communication between the second communication groove <NUM> and the third communication groove <NUM> at the first position, the second sealing wall 46d for blocking communication between the first communication groove <NUM> and the third communication groove <NUM> at the second position, and the first recess 47a formed between the second sealing wall 46d and the first guide end part 46e, allowing the first communication groove <NUM> and the third communication groove <NUM> to communicate with each other at the first position, and the second recess 47c formed between the first sealing wall 46c and the second guide end part 46f allowing the second communication groove <NUM> and the third communication groove <NUM> to communicate with each other at the second position, the return spring 26a that biases the spool <NUM> to the side of the first position, and the piston member <NUM> which displaces the spool <NUM> to the second position under an action of the pilot air flowing in from the cylinder port 12b.

The above-described drive device <NUM> comprises: the flow controller according to the present embodiment, the high pressure air supply source <NUM> that supplies the high pressure air to the air cylinder <NUM>; the exhaust port <NUM> that discharges the exhaust air of the air cylinder <NUM>; the operation switching valve <NUM> connected to one end of the high pressure air supply source, one end of the exhaust port, and one end of the main flow path, and configured to switch and thereby allow either the high pressure air supply source or the exhaust port to communicate with the main flow path.

In accordance with the above-described drive device <NUM>, by providing the flow rate controller <NUM>, the timing at which the switching valve <NUM> is operated can be stabilized.

Claim 1:
A flow rate controller, comprising:
a cylinder flow path (<NUM>) for communicating with a port of an air cylinder (<NUM>);
a main flow path (<NUM>) configured to supply and discharge air to and from the cylinder flow path;
an auxiliary flow path (<NUM>) disposed in parallel with the main flow path and including a first throttle valve (<NUM>) configured to throttle a flow rate of the air to a flow rate less than that in the main flow path;
a switching valve (<NUM>) connected to the cylinder flow path, the main flow path, and the auxiliary flow path, and configured to be switched between a first position in which the cylinder flow path is allowed to communicate with the main flow path, and a second position in which the cylinder flow path is allowed to communicate with the auxiliary flow path; and
a pilot air adjustment part (<NUM>) configured to guide a portion of exhaust air in the cylinder flow path to the switching valve as pilot air,
wherein the pilot air adjustment part includes a second throttle valve (31a) configured to regulate an inflowing speed at which the pilot air flows into the switching valve, and the switching valve is switched from the first position to the second position due to a rise in a pressure of the pilot air,
wherein the flow rate controller further comprises:
a bypass flow path (<NUM>) that is configured to bypass the switching valve and connect the cylinder flow path and the main flow path; and
a shuttle valve (<NUM>) that includes a first inlet (32a), a second inlet (32b), and an outlet (32c), wherein a first portion (28a) of the bypass flow path that communicates with the main flow path is connected to the first inlet, a second portion (28b) of the bypass flow path that communicates with the cylinder flow path is connected to the outlet, and the pilot air adjustment part is connected to the second inlet,
wherein, when a pressure in the main flow path becomes higher than a pressure in the cylinder flow path, the shuttle valve closes the second inlet to allow the first inlet and the outlet to communicate with each other, and when the pressure in the cylinder flow path becomes higher than the pressure in the main flow path, the shuttle valve closes the first inlet to allow the second inlet and the outlet to communicate with each other.