JP7137163B2 - hydraulic cylinder - Google Patents

Description

The present invention relates to fluid pressure cylinders.

2. Description of the Related Art In working machines such as clamping devices and locking devices, there are cases where normally a large driving force is not required in the first half of the working process and a large driving force is required in the latter half of the working process. For this reason, as a fluid pressure cylinder used in these working machines, there has been proposed a fluid pressure cylinder with a power boosting mechanism that increases thrust in the latter half of the forward stroke of the piston rod.

For example, in the fluid pressure cylinder disclosed in Japanese Patent Application Laid-Open No. 2018-17269, a force-increasing piston is provided as a force-increasing mechanism, and the thrust is increased by locking the force-increasing piston to the piston rod during the stroke.

In order to reduce the energy consumption of fluid pressure cylinders with power boosting mechanisms, there is a demand for further reductions in the consumption of working fluid.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fluid pressure cylinder with a power boosting function that can reduce the consumption of working fluid without complicating the structure.

One aspect of the present invention includes a cylinder body having a sliding hole extending in the axial direction, a partition wall separating the sliding hole into a head-side working cylinder chamber and an end-side boosting cylinder chamber, and an actuating piston disposed in an actuating cylinder chamber and partitioning the actuating cylinder chamber into a first pressure chamber on the head side and a second pressure chamber on the end side; a boosting piston partitioned into a third pressure chamber and a fourth pressure chamber on the end side; and a piston rod connected to the working piston and the boosting piston and extending to the end side through the partition wall. A high-pressure fluid is sealed in two adjacent pressure chambers among the first pressure chamber, the second pressure chamber, the third pressure chamber, and the fourth pressure chamber, and the operating piston is positioned closer to the head than the predetermined position. while allowing passage of high-pressure fluid between the two pressure chambers, when the actuating piston moves to the end side from the predetermined position, the high pressure between the two pressure chambers The fluid pressure cylinder is provided with a boost switching mechanism that blocks fluid conduction and exhausts high-pressure fluid in one of the two pressure chambers.

According to the fluid pressure cylinder of the present invention, high-pressure fluid is enclosed in two adjacent pressure chambers among the first to fourth pressure chambers. When the actuating piston is positioned closer to the head than the predetermined position, it allows high-pressure fluid to flow between two adjacent pressure chambers. In this case, no pressure difference occurs between the two adjacent pressure chambers, and the thrust does not increase. On the other hand, when the actuating piston moves near the end of its stroke, it blocks communication between the two adjacent pressure chambers and exhausts the high pressure fluid in one of the pressure chambers. As a result, a thrust corresponding to the pressure difference between the two adjacent pressure chambers is generated, and the thrust of the piston rod can be increased near the stroke end. Since the high-pressure fluid is exhausted at the end of the stroke, the amount of fluid used to increase thrust can be suppressed.

It is a sectional view of a fluid pressure cylinder concerning a 1st embodiment. In addition, the partial enlarged view in the figure is a cross-sectional view in which the third check valve 56 is enlarged. FIG. 2 is a side view of the end side of the fluid pressure cylinder of FIG. 1; 3A is an enlarged cross-sectional view of the vicinity of the partition wall of the fluid pressure cylinder of FIG. 1, and FIG. 3B is an enlarged cross-sectional view of the vicinity of the partition wall of FIG. 3A with the operating piston approaching. 4A is a fluid circuit diagram showing a connection state in the operation process of the fluid pressure cylinder according to the embodiment, and FIG. 4B is a fluid circuit diagram showing a connection state in the return process of the fluid pressure cylinder of FIG. 4A. FIG. 2 is a cross-sectional view of the fluid pressure cylinder of FIG. 1 in an operation process; FIG. 2 is a cross-sectional view of the fluid pressure cylinder of FIG. 1 in a force increasing process; 1. It is sectional drawing (1) in the return process of the fluid pressure cylinder of FIG. FIG. 2 is a cross-sectional view (No. 2) in the return process of the fluid pressure cylinder of FIG. 1 ; 9A is a plan view of the fluid pressure cylinder according to the second embodiment, and FIG. 9B is a side view of the fluid pressure cylinder of FIG. 9A. FIG. 10 is a cross-sectional view of the fluid pressure cylinder of FIG. 9A at the stroke start position. FIG. 11A is a hydraulic circuit diagram of the drive device of the hydraulic cylinder of FIG. 9A, showing the connection state in the first position of the switching valve, and FIG. is a fluid circuit diagram showing the connection state of the . FIG. 12 is a cross-sectional view of the fluid pressure cylinder of FIG. 9A in the step of increasing force.

Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Note that the dimensional ratios in the drawings may be exaggerated for convenience of explanation and may differ from the actual ratios. In this specification, the direction toward the terminal end of the stroke is called "end direction" or "end side", and the direction of the starting end of the stroke is called "head direction" or "head side". Moreover, in this specification, "air" means a gaseous working fluid, and is not particularly limited to air.

(First embodiment)
The fluid pressure cylinder 10 according to this embodiment includes a cylinder body 12 and a drive device 120, as shown in FIGS. 4A and 4B.

As shown in FIG. 1, the fluid pressure cylinder 10 has a cylinder body 12 elongated in the axial direction. As shown in FIG. 2, the cylinder body 12 can be rectangular and made of a metal material such as an aluminum alloy.

As shown in FIG. 1, inside the cylinder body 12, a circular slide hole 12a (cylinder chamber) extending in the axial direction is formed. The cylinder body 12 includes a head-side body portion 14 provided on the head side, an end-side body portion 16 provided on the end side, and partition walls provided between the head-side body portion 14 and the end-side body portion 16. 26 and. As shown in FIG. 2, the head-side body portion 14, the partition wall 26, and the end-side body portion 16 are axially fastened by connecting rods or bolts 16b.

As shown in FIG. 1, inside the head-side body portion 14, a circular working cylinder chamber 14a is formed, and inside the end-side body portion 16, a circular boosting cylinder chamber 16a is formed. The working cylinder chamber 14a and the boosting cylinder chamber 16a are formed to have the same inner diameter, and form a sliding hole 12a of the cylinder body 12. As shown in FIG. A partition wall 26 separates the actuating cylinder chamber 14a and the boosting cylinder chamber 16a.

An operating piston 20 is arranged in the operating cylinder chamber 14a, and a boosting piston 22 is arranged in the boosting cylinder chamber 16a. The actuating piston 20 and the boosting piston 22 are connected to a piston rod 18 extending through a diaphragm 26 and the cylinder body 12 on the end side.

The head-side body portion 14 is provided with a head-side port 28 , a head cover 46 , and an actuating piston 20 . The head cover 46 is attached to the end of the working cylinder chamber 14a on the head side, and the head side of the working cylinder chamber 14a is sealed by the head cover 46. As shown in FIG.

A head-side port 28 is formed near the head cover 46 . The head-side port 28 is formed through the head-side body portion 14 . The head-side port 28 is provided near the head-side end of the working cylinder chamber 14a and communicates with the working cylinder chamber 14a (first pressure chamber 38) through an opening 28a.

The operating piston 20 is housed in the operating cylinder chamber 14a so as to be slidable in the axial direction. An annular packing mounting groove 21a is formed in the outer peripheral surface of the operating piston 20, and a packing 21 is mounted in the packing mounting groove 21a. The packing 21 adheres to the inner peripheral surface of the working cylinder chamber 14a while elastically deforming, thereby airtightly partitioning the working cylinder chamber 14a into a first pressure chamber 38 and a second pressure chamber 40. As shown in FIG. The first pressure chamber 38 is an empty chamber formed between the working piston 20 and the head cover 46 and is formed on the head side of the working piston 20 . Also, the second pressure chamber 40 is an empty chamber formed between the working piston 20 and the partition wall 26 and is formed on the end side of the working piston 20 . The first pressure chamber 38 communicates with the head-side port 28 through an opening 28a.

The actuating piston 20 is connected to the piston rod 18 at a head-side connecting portion 18 a of the piston rod 18 and is configured to be displaced integrally with the piston rod 18 .

On the other hand, the end-side main body portion 16 is provided with a boosting piston 22 , a rod cover 48 , an end-side port 30 , and an auxiliary flow path 76 .

The power boosting piston 22 is arranged in the power boosting cylinder chamber 16a of the end-side body portion 16 so as to be slidable in the axial direction. An annular packing mounting groove 23 a and an annular magnet mounting groove 24 a are provided on the outer peripheral surface of the boosting piston 22 . An annular packing 23 made of an elastic material such as rubber is mounted in the packing mounting groove 23a. A circular ring-shaped magnet 24 is mounted in the magnet mounting groove 24a. A wear ring (not shown) is attached to the outer peripheral portion of the magnet 24 .

The booster piston 22 airtightly partitions the booster cylinder chamber 16 a into a third pressure chamber 42 and a fourth pressure chamber 44 via a packing 23 . The third pressure chamber 42 is an empty chamber on the head side of the booster piston 22 and is formed between the booster piston 22 and the partition wall 26 . Also, the fourth pressure chamber 44 is an empty chamber on the end side of the booster piston 22 and is formed between the booster piston 22 and the rod cover 48 . The fourth pressure chamber 44 communicates with the end port 30 .

An annular damper mounting groove 25a is formed in the end face of the boosting piston 22 on the head side, and a damper 25 is mounted in the damper mounting groove 25a. The damper 25 is made of an elastic material such as rubber, and is configured to prevent collision between the booster piston 22 and the partition wall 26 . The boosting piston 22 is connected to a piston mounting portion 18b provided in the central portion of the piston rod 18, and configured to be displaced integrally with the piston rod 18 in the axial direction.

The rod cover 48 is attached to the end side of the power boosting cylinder chamber 16a. The rod cover 48 is formed in a disk shape, and an annular packing mounting groove 48d is formed in the outer peripheral portion thereof. A circular ring-shaped packing 48c is mounted in the packing mounting groove 48d. The packing 48c hermetically seals the packing mounting groove 48d.

An insertion hole 48a for inserting the piston rod 18 is formed in the vicinity of the radial center of the rod cover 48 so as to extend in the axial direction. A rod packing 48b that prevents air from leaking along the piston rod 18 is provided in the insertion hole 48a. An annular damper mounting groove 47a is formed in the end face of the rod cover 48 on the head side, and a damper 47 is mounted in the damper mounting groove 47a. The damper 47 is made of a circular ring-shaped elastic member and protrudes toward the booster cylinder chamber 16a to prevent the booster piston 22 from colliding with the rod cover 48 .

A retainer clip 49 for fixing the rod cover 48 is attached to the end side of the rod cover 48 . The retaining clip 49 is a plate member engaged with an engaging groove 49a formed along the inner peripheral surface of the end-side body portion 16. As shown in FIG. The retainer clip 49 is an annular plate member with a portion notched in the circumferential direction. To prevent the cover 48 from coming off.

The end-side port 30 is formed in the vicinity of the end-side end of the end-side body portion 16 . The end-side port 30 is formed so as to penetrate from the outer periphery of the end-side body portion 16 toward the booster cylinder chamber 16a, and communicates with the fourth pressure chamber 44 at the end-side end of the booster cylinder chamber 16a. there is

The auxiliary flow path 76 is a flow path formed inside the end-side body portion 16 and extends in the axial direction. One end of the auxiliary flow path 76 communicates with the end-side port 30, and the other end communicates with an adjustment port 32 of the partition wall 26, which will be described later.

The third check valve 56 is provided in the middle of the auxiliary flow path 76 . The third check valve 56 has a hollow portion 56a having a diameter larger than that of the auxiliary flow path 76, and a valve body 56b inserted into the hollow portion 56a. It is a cylindrical cup-shaped member with a bottom, and the bottom 56c is arranged downstream in the direction of blocking the air flow. A bottom 56c of the valve body 56b is formed with an annular protrusion 56d that abuts against the end face of the hollow portion 56a and closes the auxiliary flow path 76 that communicates with the hollow portion 56a.

A notch portion 56e is formed in the side portion of the valve body 56b for allowing air to pass therethrough. The annular protrusion 56d of the valve body 56b is separated from the end surface of the hollow portion 56a to allow the air flowing from the bottom 56c side to pass through the notch 56e. Also, against the air directed in the opposite direction, the bottom 56c of the valve body 56b receives the pressure of the air, and the annular protrusion 56d comes into contact with the end face of the hollow portion 56a to block the auxiliary flow path 76. and is configured to block the flow of air.

In order to make the operation of the third check valve 56 smooth, an urging member 56f such as a spring for urging the annular protrusion 56d of the valve body 56b in a direction of abutting against the end face of the cavity 56a is provided in the cavity 56a. may be provided. Also, a first check valve 52 and a second check valve 54 , which will be described later, have the same structure as the third check valve 56 .

The partition 26 has a plate-like main body 60, as shown in FIG. 3A. The main body 60 is formed with a first connecting portion 63 that protrudes toward the head side and is inserted into the operating cylinder chamber 14a, and a second connecting portion 64 that protrudes toward the end side and is inserted into the boosting cylinder chamber 16a. The first connecting portion 63 is formed in a columnar shape with an outer diameter substantially the same as the inner diameter of the operating cylinder chamber 14a, and a packing 63a is attached to the outer peripheral portion thereof. The second connecting portion 64 is formed in a columnar shape with an outer diameter substantially the same as the inner diameter of the power boosting cylinder chamber 16a, and a packing 64a is attached to the outer peripheral portion thereof. The packing 63 a seals the gap between the operating cylinder chamber 14 a and the first connecting portion 63 , and the packing 64 a seals the gap between the boosting cylinder chamber 16 a and the second connecting portion 64 .

A through portion 61 for inserting the piston rod 18 is formed extending in the axial direction near the center in the radial direction of the partition wall 26 . The through portion 61 is provided with a packing 62 that prevents air from leaking along the piston rod 18 .

The partition wall 26 includes a communication path 34, a conduction switching valve 35 provided in the communication path 34, an exhaust path 36, and an exhaust switching valve 37 provided in the exhaust path 36, which constitute the boost switching mechanism 33. have

The communication path 34 is a flow path for circulating air between the second pressure chamber 40 and the third pressure chamber 42, and includes a through hole 65 axially penetrating the partition wall 26, and a through hole 65 inserted into the through hole 65. It is composed of the internal channel 35 e of the conduction switching pin 35 a and the hole 66 b of the stopper 66 .

The through hole 65 is formed through the partition wall 26 in the axial direction, and includes a large diameter portion 65a formed on the head side, a small diameter portion 65b formed in the axial center, and and a stopper insertion hole 65c. The large diameter portion 65a and the stopper insertion hole 65c are formed to have inner diameters larger than those of the small diameter portion 65b. The conduction switching pin 35a is inserted into the large diameter portion 65a and the small diameter portion 65b. A stopper 66 is inserted into the stopper insertion hole 65c. The stopper 66 is connected to the end side of the conduction switching pin 35a of the conduction switching valve 35, and is displaced integrally with the conduction switching pin 35a. Further, the stopper 66 stops in the stopper insertion hole 65c, thereby restricting the movement of the conduction switching pin 35a toward the head.

The conduction switching valve 35 is configured with a conduction switching pin 35a. The conduction switching pin 35a has a closed portion 35c formed on the head side and a rod portion 35d axially extending toward the end side. The rod portion 35d is formed to have substantially the same diameter as the inner diameter of the small diameter portion 65b of the through hole 65, and is axially slidably inserted into the small diameter portion 65b. The closing portion 35c is formed to have substantially the same diameter as the inner diameter of the large-diameter portion 65a of the through-hole 65, and is configured to be insertable into the large-diameter portion 65a. A ring-shaped packing 35b is attached to the outer peripheral portion of the closing portion 35c. The packing 35b is configured to adhere to the large diameter portion 65a to seal the communication passage 34 when the closing portion 35c is pushed into the large diameter portion 65a.

A biasing member 35f is mounted on the end side of the closing portion 35c of the conduction switching pin 35a. The biasing member 35f is made of, for example, a spring, and is inserted into the gap between the large diameter portion 65a and the conduction switching pin 35a. The urging member 35f urges the conduction switching pin 35a toward the head to separate the closing portion 35c from the through hole 65 and protrude toward the second pressure chamber 40 side. In other words, the conduction switching valve 35 is configured so as not to block the conduction of the communication path 34 in a state where the conduction switching pin 35a is not pressed toward the head side by the actuating piston 20 .

On the other hand, the exhaust path 36 is open at the end face of the partition wall 26 on the side of the first connection portion 63 and extends in the axial direction. 71. Among them, the detection pin accommodation hole 67 has a large diameter portion 67a formed on the head side, a small diameter portion 67b formed on the end side of the large diameter portion 67a, and a stopper insertion hole 67c. A stopper 68 is inserted into the stopper insertion hole 67c. The stopper 68 is connected to the detection pin 37a and displaces together with the detection pin 37a. The stopper 68 restricts the movement range of the detection pin 37a toward the head by stopping at the end of the small diameter portion 67b.

The connection channel 71 communicates with the detection pin housing hole 67 at an opening 71a formed on the side of the small diameter portion 67b. The small-diameter portion 67 b is enlarged in a predetermined range around the opening 71 a to form a gap with the exhaust switching valve 37 .

The connection channel 71 is provided with a first check valve 52 that allows air to pass only in the direction from the opening 71 a to the adjustment port 32 . The first check valve 52 is arranged in an orientation that allows air to be exhausted from the second pressure chamber 40 .

The exhaust switching valve 37 has a detection pin 37a. The detection pin 37a includes a pin main body portion 37b extending in the axial direction in a cylindrical shape and a flange portion 37c extending radially outward from the head-side end portion of the pin main body portion 37b. The flange portion 37c has a diameter slightly smaller than the inner diameter of the large diameter portion 67a, and is configured to be insertable into the large diameter portion 67a. A biasing member 37f such as a spring is attached to the large diameter portion 67a. The biasing member 37f is configured to make the flange portion 37c protrude toward the second pressure chamber 40 by contacting the flange portion 37c and biasing the detection pin 37a toward the head side.

The pin body portion 37b is formed to have a diameter slightly smaller than the inner diameter of the small diameter portion 67b, and is configured to be axially slidable along the small diameter portion 67b. A packing 37d and a packing 37e are arranged axially apart from each other on the outer peripheral portion of the pin body portion 37b. The packings 37d and 37e are arranged in a position where they are in close contact with the small diameter portion 67b and block the communication between the detection pin housing hole 67 and the connecting passage 71 when the detection pin 37a is not pressed by the actuating piston 20. there is In other words, the exhaust switching valve 37 blocks the communication of the exhaust passage 36 when it is not pressed by the operating piston 20 .

A replenishment flow path 78 and a second check valve 54 are provided in the head-side body portion 14 near the adjustment port 32 . The supplementary flow path 78 communicates with the adjustment port 32 and the second pressure chamber 40 . A second check valve 54 is provided in the replenishment flow path 78 . One end of the second check valve 54 communicates with the adjustment port 32 via the replenishment flow path 78 . Also, the other end of the second check valve 54 communicates with the second pressure chamber 40 via the replenishment flow path 78 . The second check valve 54 allows passage of air only in the direction from the adjustment port 32 toward the second pressure chamber 40 and blocks passage of air in the opposite direction. That is, the second check valve 54 is configured to allow the flow of air replenished to the second pressure chamber 40 and block the air flowing in the opposite direction.

The fluid pressure cylinder 10 of this embodiment is configured as described above, and is driven by the driving device 120 as shown in FIG. 4A.

The driving device 120 includes a fourth check valve 86 , a throttle valve 88 , a switching valve 102 , a high pressure air supply source (high pressure fluid supply source) 104 and an exhaust port 106 . The driving device 120 is configured to supply high-pressure air to the first pressure chamber 38 of the operating cylinder chamber 14a in the operating process. Further, as shown in FIG. 4B , the driving device 120 supplies part of the air accumulated in the first pressure chamber 38 toward the fourth pressure chamber 44 and also supplies the air accumulated in the second pressure chamber 40 in the return process. It is configured to supply high pressure air.

The switching valve 102 is, for example, a 5-port 2-position type valve, has a first port 102a to a fifth port 102e, and switches between a first position (see FIG. 4A) and a second position (see FIG. 4B). It is possible. As shown in FIGS. 4A and 4B, the first port 102a is connected to the head side port 28 by piping. The second port 102b is connected to the adjustment port 32 by piping. The third port 102c is connected to the exhaust port 106 by piping. The fourth port 102d is connected to the high pressure air supply source 104 by piping. The fifth port 102e is connected to the exhaust port 106 via a throttle valve 88 and to the end port 30 via a fourth check valve 86 by piping.

As shown in FIG. 4A, when the switching valve 102 is in the first position, the first port 102a and the fourth port 102d are connected, and the second port 102b and the third port 102c are connected.

Also, as shown in FIG. 4B, when the switching valve 102 is in the second position, the first port 102a and the fifth port 102e are connected, and the second port 102b and the fourth port 102d are connected. The switching valve 102 is switched between the first position and the second position by pilot pressure from the high pressure air supply source 104 or by an electromagnetic valve.

The fourth check valve 86 allows air to flow from the head-side port 28 to the end-side port 30 when the switching valve 102 is in the second position. block the flow.

The throttle valve 88 is provided to limit the amount of air in the first pressure chamber 38 that is exhausted from the exhaust port 106, and is a variable throttle valve that can change the passage area so that the exhaust flow rate can be adjusted. is configured as

An air tank is provided in the middle of the pipe connecting the fourth check valve 86 and the fourth pressure chamber 44 to store the air supplied from the head side port 28 to the end side port 30 in the return process. good too. By providing the air tank, a sufficient amount of air can be accumulated to fill the fourth pressure chamber 44 during the return operation, and the return operation can be stabilized. In this case, the capacity of the air tank may be set to approximately half the maximum capacity of the first pressure chamber 38, for example. If sufficient piping capacity can be secured, an air tank is not necessary.

The fluid pressure cylinder 10 and the driving device 120 are configured as described above, and their actions and operations will be described below.

(Startup process)
In the starting step, the second pressure chamber 40 and the third pressure chamber 42 are filled with high-pressure air before the fluid pressure cylinder 10 is started to be used. The high pressure air is air having a pressure higher than the atmospheric pressure. Here, the fluid pressure cylinder 10 is set at the starting end position of the stroke as shown in FIG. Also, the switching valve 102 of the driving device 120 is set to the second position (see FIG. 4B). This connects the high pressure air supply 104 to the adjustment port 32 . As shown in FIG. 4B, high pressure air from the high pressure air supply source 104 is introduced into the second pressure chamber 40 via the second check valve 54 . The high-pressure air introduced into the second pressure chamber 40 is also introduced into the third pressure chamber 42 via the communication passage 34 . As a result, the second pressure chamber 40 and the third pressure chamber 42 are filled with high-pressure air. The activation step need only be performed once before the first stroke of hydraulic cylinder 10 .

(Operating process)
As shown in FIG. 4A, the operation process of the hydraulic cylinder 10 is performed with the switching valve 102 of the driving device 120 in the first position. High pressure air from a high pressure air supply source 104 is supplied to the head side port 28 via the first port 102 a of the switching valve 102 . The fourth check valve 86 is connected to the fifth port 102e side, and high pressure air does not flow to the fourth check valve 86 side. The fourth pressure chamber 44 is connected to the exhaust port 106 via the third check valve 56, the adjustment port 32 and the second port 102b.

As shown in FIG. 5, during an actuation step, high pressure air from high pressure air supply 104 flows into first pressure chamber 38 as indicated by arrow B. As shown in FIG. The force acting on the actuating piston by the high pressure air in the second pressure chamber 40 and the force acting on the boosting piston 22 by the high pressure air filled in the third pressure chamber 42 are the same and are balanced in opposite directions. does not contribute. Therefore, a thrust corresponding to the pressure difference between the first pressure chamber 38 adjacent to the operating piston 20 and the fourth pressure chamber 44 adjacent to the boosting piston 22 is generated in the piston rod 18, and the piston rod 18 moves to the end side. Stroke toward.

As the actuating piston 20 strokes, the hydraulic cylinder 10 is supplied with a volume of high pressure air equal to the volume of the first pressure chamber 38 from a high pressure air source 104 (see FIG. 4A). High-pressure air in the second pressure chamber 40 moves to the third pressure chamber 42 through the communication passage 34 as the actuating piston 20 and the boosting piston 22 stroke. During the operation process, the pressure of the high pressure air stored in the second pressure chamber 40 and the third pressure chamber 42 is kept constant. Further, the air in the fourth pressure chamber 44 is exhausted from the fourth pressure chamber 44 as the boost piston 22 strokes. In this case, the air in the fourth pressure chamber 44 passes through the adjustment port 32 via the third check valve 56 and the auxiliary flow path 76, and as shown in FIG. exhausted from

(Power boosting process)
As shown in FIG. 6, along with the stroke of the operating piston 20, the conduction switching pin 35a (see FIG. 3B) of the conduction switching valve 35 is pressed toward the end side, and the detection pin 37a (see FIG. 3B) of the exhaust switching valve 37 ) are also pressed toward the end.

As a result, the closed portion 35c of the conduction switching pin 35a is inserted into the large diameter portion 65a of the through hole 65, as shown in FIG. 3B. The packing 35b of the blocking portion 35c seals the gap between the large-diameter portion 65a and the blocking portion 35c, thereby blocking the communication passage 34. As shown in FIG. In other words, the conduction switching valve 35 prevents the flow of air between the second pressure chamber 40 and the third pressure chamber 42 through the communication passage 34 .

Further, the detection pin 37a of the exhaust switching valve 37 is displaced to the end side, so that the packing 37d sealing the gap between the detection pin 37a and the detection pin housing hole 67 moves to the recessed opening 71a. do. As a result, the exhaust path 36 is opened, and the adjustment port 32 and the second pressure chamber 40 communicate with each other through the exhaust path 36 . The high pressure air accumulated in the second pressure chamber 40 is exhausted from the exhaust port 106 via the first check valve 52 and the adjustment port 32 . As a result, the internal pressure of the second pressure chamber 40 decreases, and a thrust corresponding to the difference in internal pressure between the second pressure chamber 40 and the first pressure chamber 38 is generated in the operating piston 20 .

Further, in the boosting piston 22, a thrust corresponding to the pressure difference between the pressure of the high-pressure air stored in the third pressure chamber 42 and the pressure of the fourth pressure chamber 44 is generated. As a result, the fluid pressure cylinder 10 can increase thrust in the vicinity of the stroke end. An increase in thrust in the fluid pressure cylinder 10 is produced by exhausting high-pressure air from the second pressure chamber 40 within a range in which the conduction switching valve 35 and the exhaust switching valve 37 operate.

(recovery process)
As shown in FIG. 4B, the return process of the fluid pressure cylinder 10 is performed with the switching valve 102 of the driving device 120 set to the second position. High-pressure air from a high-pressure air supply source 104 is supplied to the adjustment port 32 via the second port 102b of the switching valve 102 . The first port 102a of the switching valve 102 is connected to the fifth port 102e, and the head side port 28 is connected to the end side port 30 via the fourth check valve 86. Also, the head side port 28 is connected to the exhaust port 106 via the throttle valve 88 . As a result, part of the air stored in the first pressure chamber 38 is supplied to the fourth pressure chamber 44 via the fourth check valve 86 side. Also, the remaining part of the air stored in the first pressure chamber 38 is exhausted from the exhaust port 106 .

As shown in FIG. 7, in the return process, high-pressure air is supplied from the high-pressure air supply source 104 to the adjustment port 32 of the fluid pressure cylinder 10 as indicated by an arrow B. As shown in FIG. The high-pressure air supplied to the adjustment port 32 flows into the second pressure chamber 40 through the supplementary flow path 78 and the second check valve 54 . The volume of high-pressure air supplied to the second pressure chamber 40 is equal to the volume of high-pressure air exhausted from the second pressure chamber 40 during the boosting process. That is, the high-pressure air required for the boosting process is replenished in the returning process. The amount of high-pressure air supplied at that time is small compared to the amount of high-pressure air required for the stroke of the operating piston 20, and only a small amount of high-pressure air needs to be added.

In the return process, since the internal pressure of the second pressure chamber 40 becomes equal to the internal pressure of the third pressure chamber 42, the force exerted by the second pressure chamber 40 on the operating piston 20 and the force exerted by the third pressure chamber 42 on the boost piston 22 balance and cancel each other out.

On the other hand, part of the high-pressure air exhausted from the first pressure chamber 38 flows into the fourth pressure chamber 44 as indicated by an arrow A. As the air in the first pressure chamber 38 is exhausted, the pressure difference between the fourth pressure chamber 44 and the first pressure chamber 38 increases, causing the working piston 20, boosting piston 22 and piston rod 18 to move toward the head. Start. Along with this, the conduction switching valve 35 returns to its original position, and the second pressure chamber 40 and the third pressure chamber 42 communicate with each other through the communication passage 34 . Also, the exhaust switching valve 37 seals the exhaust path 36 to prevent communication between the adjustment port 32 and the second pressure chamber 40 .

After that, as shown in FIG. 8, while air flows into the fourth pressure chamber 44, exhaustion of the first pressure chamber 38 progresses, and the operating piston 20 and the boosting piston 22 return to the starting end positions of their strokes. is completed.

The fluid pressure cylinder 10 according to this embodiment has the following effects.

In the fluid pressure cylinder 10, the fluid pressure cylinder 10 includes a communication passage 34 communicating with the second pressure chamber 40 and the third pressure chamber 42 and an exhaust passage 36 communicating with the second pressure chamber 40 as the boost switching mechanism 33. a conduction switching valve 35 that opens the communication passage 34 while the working piston 20 is positioned closer to the head than the predetermined position and closes the communication passage 34 when the working piston 20 moves toward the end side of the predetermined position; The exhaust path 36 is closed while the working piston 20 is positioned closer to the head side than the predetermined position, and the exhaust path 36 is opened to open the second pressure chamber 40 when the working piston 20 moves to the end side of the predetermined position. and an exhaust switching valve 37 for exhausting the high-pressure fluid. As a result, the second pressure chamber 40 and the third pressure chamber 42 are separated near the stroke end, and the high pressure air in the second pressure chamber 40 can be exhausted while maintaining the high pressure air in the third pressure chamber 42 . As a result, the thrust of the power boosting piston 22 is added to the thrust of the operating piston 20, and the thrust can be increased in the latter half of the stroke.

In the fluid pressure cylinder 10 , the partition 26 may have an adjustment port 32 , and the exhaust passage 36 may exhaust the high-pressure fluid in the second pressure chamber 40 via the adjustment port 32 .

In the fluid pressure cylinder 10 , the boost switching mechanism 33 may cause the exhaust switching valve 37 to open the exhaust path 36 after the conduction switching valve 35 closes the communication path 34 . As a result, it is possible to prevent the high-pressure air from flowing out of the third pressure chamber 42 via the second pressure chamber 40, thereby reducing the amount of high-pressure air used.

In the fluid pressure cylinder 10 , the conduction switching valve 35 has a conduction switching pin 35 a with one end protruding toward the second pressure chamber 40 side and the other end inserted into the communication passage 34 . The communication path 34 may be closed by being bent and displaced toward the end. As a result, the conduction switching valve 35 can be operated using the stroke motion of the actuating piston 20, and the device configuration can be simplified.

In the fluid pressure cylinder 10, the exhaust switching valve 37 seals the exhaust path 36 and has a detection pin 37a with one end protruding into the second pressure chamber 40. The detection pin 37a is pressed by the operating piston 20 to open the end. The sealing of the exhaust path 36 may be released by displacing to the side. As a result, the second pressure chamber 40 can be exhausted through the exhaust passage 36 by using the stroke motion of the actuating piston 20, thereby simplifying the device configuration.

In the fluid pressure cylinder 10, even if the exhaust path 36 is provided with a first check valve 52 that allows air to pass only in the direction from the second pressure chamber 40 to the adjustment port 32 and blocks air in the opposite direction. good. As a result, malfunction of the exhaust switching valve 37 can be prevented in the recovery process.

The fluid pressure cylinder 10 further has a replenishment passage 78 that communicates with the adjustment port 32 and the second pressure chamber 40 , and the replenishment passage 78 receives air only in the direction from the adjustment port 32 toward the second pressure chamber 40 . A second check valve 54 may be provided to allow air to pass through and block air in the opposite direction. By providing the second check valve 54, inflow of excessive high-pressure air into the second pressure chamber 40 can be suppressed in the return process.

The fluid pressure cylinder 10 described above may further include an auxiliary flow path 76 that communicates with the fourth pressure chamber 44 and the adjustment port 32 . As a result, the air in the fourth pressure chamber 44 can be exhausted through the adjustment port 32 in the actuation process and the power boosting process.

In the fluid pressure cylinder 10 described above, the auxiliary passage 76 is provided with a third check valve 56 that allows only the air flowing in the direction from the fourth pressure chamber 44 to the adjustment port 32 to pass therethrough and blocks the air in the opposite direction. may be As a result, when high pressure air is supplied to the adjustment port 32 in the return process, it is possible to prevent the high pressure air from flowing into the fourth pressure chamber 44, thereby suppressing the consumption of high pressure air.

The fluid pressure cylinder 10 further includes a drive device 120 connected to the first pressure chamber 38, the second pressure chamber 40 and the fourth pressure chamber 44 of the fluid pressure cylinder 10. The drive device 120 includes the switching valve 102 and the high pressure It has an air supply source 104, an exhaust port 106, and a fourth check valve 86. When the switching valve 102 is in the first position, the first pressure chamber 38 communicates with the high pressure air supply source 104 and the fourth pressure chamber 44 and the adjustment port 32 (power boost switching mechanism 33) communicate with the exhaust port 106, and when the switching valve 102 is in the second position, the first pressure chamber 38 communicates with the fourth pressure chamber 44 via the fourth check valve 86. In addition, the first pressure chamber 38 may communicate with the exhaust port 106 and the second pressure chamber 40 may communicate with the high pressure air supply source 104 via the adjustment port 32 . As a result, in the return process, the air accumulated in the first pressure chamber 38 can be supplied to the fourth pressure chamber 44, so the consumption of high pressure air can be suppressed.

A throttle valve 88 may be provided between the first pressure chamber 38 and the exhaust port 106 in the fluid pressure cylinder 10 described above. Thereby, the amount of air supplied to the fourth pressure chamber 44 can be appropriately adjusted.

(Second embodiment)
As shown in FIG. 9A, the fluid pressure cylinder 10A of this embodiment has a head side body portion 14A and an end side body portion 16A. In this embodiment, the end-side body portion 16A is filled with a high-pressure fluid. In order to further increase the thrust at the stroke end, the size (width and height) of the end-side body portion 16A is made larger than the size of the head-side body portion 14A.

As shown in FIG. 9B, the head-side main body portion 14A and the end-side main body portion 16A are formed to have rectangular cross sections. The head-side body portion 14A and the end-side body portion 16A are axially connected by connecting rods or bolts.

As shown in FIG. 10, the cylinder body 12A of the fluid pressure cylinder 10A includes a head-side main body portion 14A and an end-side main body portion 16A, which are axially connected via a partition wall portion 126. As shown in FIG. The head-side body portion 14A is provided with a head-side port 28A and an end-side port 30A. An adjustment port 32A is provided near the end on the end side of the end-side body portion 16A.

A stored air exhaust port 162 is formed in the vicinity of the outer periphery of the partition wall 126 to exhaust the high pressure air enclosed in the power boosting cylinder chamber 116a. The stored air exhaust port 162 communicates with the third pressure chamber 42 via the regulating valve 160 . The stored air exhaust port 162 discharges high pressure air stored in the power boosting cylinder chamber 116a during maintenance of the fluid pressure cylinder 10A, etc., and introduces high pressure air into the power boosting cylinder chamber 116a when starting. used for

A central portion of the partition wall portion 126 is formed with an insertion hole 126c through which the piston rod 18A is slidably inserted. The insertion hole 126c is provided with a packing 118 for preventing leakage of fluid in the axial direction. The partition wall portion 126 is provided with a head-side connection portion 126a that extends toward the head side and is inserted into the working cylinder chamber 14a. An end-side connecting portion 126b that is inserted into the power boosting cylinder chamber 116a is provided on the end side of the partition wall portion 126. As shown in FIG. An annular cushioning member 124 is attached to the end-side connecting portion 126b to avoid collision with the boosting piston 22A.

The end-side body portion 16A has a body portion 116 . Inside the body portion 116, a boosting cylinder chamber 116a is formed which is a circular hollow portion. The booster cylinder chamber 116a extends in the axial direction. Inside the booster cylinder chamber 116a, a booster piston 22A is arranged so as to be slidable in the axial direction. Boosting piston 22A is connected to piston rod 18A. A magnet 24 and a packing 23 are attached to the outer peripheral portion of the boosting piston 22A. The booster piston 22A divides the booster cylinder chamber 116a into a third pressure chamber 42 on the head side and a fourth pressure chamber 44 on the end side.

Further, the power boosting piston 22A is provided with a conduction switching valve 35A for switching the conduction state of the high-pressure fluid between the third pressure chamber 42 and the fourth pressure chamber 44 which are axially adjacent to each other. The conduction switching valve 35A includes a through hole 122 axially penetrating the boosting piston 22A, and a conduction switching pin 35a inserted into the through hole 122. As shown in FIG.

The through-hole 122 has an end-side enlarged diameter portion 122a, a diameter-reduced portion 122b, and a head-side enlarged diameter portion 122c. The conduction switching pin 35a of the conduction switching valve 35A is the same as the conduction switching pin 35a described with reference to FIG. 3A. The rod portion 35d of the conduction switching pin 35a is inserted into the reduced diameter portion 122b. A closing portion 35c of the conduction switching pin 35a is arranged on the side of the end-side enlarged diameter portion 122a. The conduction switching pin 35a protrudes to the end side by the biasing force of the biasing member 35f.

High pressure air can be conducted between the third pressure chamber 42 and the fourth pressure chamber 44 via the through hole 122 and the internal flow path 35e of the conduction switching pin 35a. That is, in this embodiment, the through hole 122 and the internal flow path 35e form a communication path. Further, when the boosting piston 22A moves to the end side, the conduction switching pin 35a is pressed by the rod cover 48A, and the closing portion 35c and the packing 35b on the outer periphery thereof are inserted into the through hole 122, closing the through hole 122. , and block electrical connection between the third pressure chamber 42 and the fourth pressure chamber 44 .

The rod cover 48A is provided near the end on the end side of the end-side body portion 16A, and seals the end on the end side of the booster cylinder chamber 116a. The rod cover 48A is provided with an exhaust switching valve 37A for switching exhaust of high-pressure air in the fourth pressure chamber 44. As shown in FIG. The exhaust switching valve 37A includes a through hole 139 axially penetrating the rod cover 48A and a detection pin 137 inserted into the through hole 139 .

The through-hole 139 is closed at its end by a lid member 150 , and a detection pin 137 is provided on the head side of the lid member 150 . The detection pin 137 is biased toward the head by a biasing member 140 such as a spring disposed between the lid member 150 and the detection pin 137 . Therefore, the tip of the detection pin 137 on the head side protrudes into the fourth pressure chamber 44 .

Annular packings 141 and 142 are attached to the outer peripheral portion of the base end portion 138 of the detection pin 137 so as to be separated from each other in the axial direction. The packing 141 and the packing 142 seal the gap between the through hole 139 and the detection pin 137 . A flow path 143 is provided between the packing 141 and the packing 142 . The channel 143 communicates with the through hole 139 on the inside and communicates with the ventilation groove 144 on the outside. The ventilation groove 144 is an annular groove formed over the entire circumferential direction of the outer peripheral portion of the rod cover 48A, and communicates with the adjustment port 32A. A packing 146 is provided on the head side of the ventilation groove 144, and a packing 148 is provided on the end side thereof. These packings 146 and 148 keep the ventilation groove 144 airtight. The adjustment port 32</b>A can communicate with the fourth pressure chamber 44 via the ventilation groove 144 , the flow path 143 and the through hole 139 . That is, in this embodiment, the through holes 139, the flow paths 143, and the ventilation grooves 144 constitute the exhaust path.

When the detection pin 137 is moved toward the head, the through hole 139 is closed by the packings 141 and 142, and the high pressure fluid in the fourth pressure chamber 44 is not discharged. On the other hand, when the boosting piston 22A moves toward the end side, the detection pin 137 is pushed toward the end side, and the packings 141 and 142 move toward the end side of the flow path 143 . When the packings 141 and 142 move toward the end side of the flow path 143, the fourth pressure chamber 44 communicates with the adjustment port 32A.

The fluid pressure cylinder 10A of this embodiment configured as described above is driven by a driving device 120A shown in FIGS. 11A and 11B.

As shown in FIG. 11A, the driving device 120A includes a fourth check valve 86, a throttle valve 88, a switching valve 102, a high pressure air supply source 104, an exhaust port 106, and a fifth check valve 108. there is The driving device 120A is configured to supply high-pressure air to the first pressure chamber 38 of the operating cylinder chamber 14a in the operating process. Further, as shown in FIG. 11B, the driving device 120A supplies part of the air accumulated in the first pressure chamber 38 toward the second pressure chamber 40, It is configured to supply high pressure air.

The switching valve 102 is, for example, a 5-port 2-position type valve, has a first port 102a to a fifth port 102e, and switches between a first position (see FIG. 11A) and a second position (see FIG. 11B). It is possible. As shown in FIGS. 11A and 11B, the first port 102a is connected to the head side port 28A by piping. The second port 102b is connected to the adjustment port 32A and the downstream side of the fifth check valve 108 by piping. The third port 102c is connected to the exhaust port 106 by piping. The fourth port 102d is connected to the high pressure air supply source 104 by piping. The fifth port 102e is connected by piping to the exhaust port 106 via the throttle valve 88 and to the upstream side of the end-side port 30A and the fifth check valve 108 via the fourth check valve 86. .

As shown in FIG. 11A, when the switching valve 102 is in the first position, the first port 102a and the fourth port 102d are connected, and the second port 102b and the third port 102c are connected.

Also, as shown in FIG. 11B, when the switching valve 102 is in the second position, the first port 102a and the fifth port 102e are connected, and the second port 102b and the fourth port 102d are connected. The switching valve 102 is switched between the first position and the second position by pilot pressure from the high pressure air supply source 104 or by an electromagnetic valve.

When the switching valve 102 is in the second position, the fourth check valve 86 allows air to flow from the head-side port 28A to the end-side port 30A, and allows air to flow from the end-side port 30A to the head-side port 28A. block the flow. Further, the fifth check valve 108 blocks the flow of high pressure air from the second port 102b to the end side port 30A when the switching valve 102 is in the second position.

The fluid pressure cylinder 10A and its drive device 120A according to the present embodiment are configured as described above, and their effects and operations will be described below.

(Operating process)
As shown in FIG. 11A, the operation process of the fluid pressure cylinder 10A is performed with the switching valve 102 of the driving device 120A set to the first position. High pressure air from a high pressure air supply source 104 is supplied to the head side port 28 via the first port 102 a of the switching valve 102 . The fourth check valve 86 is connected to the fifth port 102e side, and high pressure air does not flow to the fourth check valve 86 side. The second pressure chamber 40 is connected to the exhaust port 106 via the end side port 30A and the fifth check valve 108 . Also, the adjustment port 32A is connected to the exhaust port 106 .

As shown in FIG. 10, in the operating process, high pressure air from the high pressure air supply source 104 flows into the first pressure chamber 38 from the head side port 28A. As a result, a thrust toward the end side is generated in the operating piston 20 . As a result, the piston rod 18A strokes toward the end side. The high-pressure air enclosed in the third pressure chamber 42 and the fourth pressure chamber 44 is conducted through the conduction switching valve 35A, so no thrust is generated in the booster piston 22A.

High-pressure air corresponding to the volume of the first pressure chamber 38 is supplied from the high-pressure air supply source 104 (see FIG. 11A) to the fluid pressure cylinder 10A along with the stroke of the operating piston 20 . During the operation process, the pressure of the high pressure air stored in the second pressure chamber 40 and the third pressure chamber 42 is kept constant. Also, the air in the second pressure chamber 40 is exhausted from the second pressure chamber 40 as the working piston 20 strokes. In this case, the air in the second pressure chamber 40 passes through the end-side port 30A and the fifth check valve 108 and is exhausted from the exhaust port 106, as shown in FIG. 11A.

(Power boosting process)
As shown in FIG. 12, along with the stroke of the booster piston 22A, the conduction switching pin 35a of the conduction switching valve 35A is pushed toward the head side, and the detection pin 37a of the exhaust switching valve 37A is pushed toward the end side.

As a result, the closing portion 35c of the conduction switching pin 35a is inserted into the through hole 122 to close the through hole 122. As shown in FIG. As a result, conduction of high pressure air between the third pressure chamber 42 and the fourth pressure chamber 44 is blocked.

Further, the detection pin 37a of the exhaust switching valve 37A is displaced toward the end side, whereby the packings 141 and 142 sealing the gap between the detection pin 37a and the through hole 139 are removed from the flow path 143, and the adjustment port 32A and the fourth pressure chamber 44 are communicated. As a result, the high pressure air stored in the fourth pressure chamber 44 is exhausted from the exhaust port 106 . That is, while high-pressure air is retained in the third pressure chamber 42, the internal pressure of the fourth pressure chamber 44 decreases. As a result, a thrust corresponding to the difference in internal pressure between the fourth pressure chamber 44 and the third pressure chamber 42 is generated in the booster piston 22A. Since this thrust is added to the thrust of the operating piston 20, the thrust of the fluid pressure cylinder 10A increases near the stroke end. Thus, the increase in thrust of the fluid pressure cylinder 10A is produced by exhausting the high pressure air in the fourth pressure chamber 44 within the range where the conduction switching valve 35A and the exhaust switching valve 37A operate.

(recovery process)
As shown in FIG. 11B, the return process of the fluid pressure cylinder 10A is performed with the switching valve 102 of the drive device 120A set to the second position. High-pressure air from a high-pressure air supply source 104 is supplied through the second port 102b of the switching valve 102 to the adjustment port 32A. The first port 102a of the switching valve 102 is connected to the fifth port 102e, and the head side port 28A is connected through the fourth check valve 86 to the end side port 30A. Further, the head side port 28A is connected to the exhaust port 106 through the throttle valve 88. As shown in FIG. As a result, part of the air stored in the first pressure chamber 38 is supplied to the fourth pressure chamber 44 via the fourth check valve 86 side. Also, the remaining part of the air stored in the first pressure chamber 38 is exhausted from the exhaust port 106 .

In the return process, high pressure air is supplied from the high pressure air supply source 104 to the adjustment port 32A of the fluid pressure cylinder 10A. The high pressure air supplied to the adjustment port 32A flows into the fourth pressure chamber 44. As shown in FIG. As a result, the high pressure air exhausted in the power boosting process is replenished. The amount of high-pressure air replenished at that time is very small compared to the amount of high-pressure air required for the stroke of the operating piston, and only a small amount of high-pressure air needs to be added.

On the other hand, part of the high pressure air discharged from the first pressure chamber 38 flows into the second pressure chamber 40 . As the air in the first pressure chamber 38 is exhausted, the pressure difference between the fourth pressure chamber 44 and the first pressure chamber 38 increases, and the working piston 20 moves toward the head. Then, the actuating piston 20 and the boosting piston 22A return to their stroke start positions, completing the return process. In this manner, the air required for returning the operating piston 20 is supplied from the first pressure chamber 38, so there is no need to supply high pressure air to the second pressure chamber 40. FIG.

The fluid pressure cylinder 10A according to this embodiment has the following effects.

In the fluid pressure cylinder 10A of this embodiment, high-pressure fluid is sealed in the third pressure chamber 42 and the fourth pressure chamber 44, and the boost switching mechanism 33A includes a conduction switching valve 35A provided in the boost piston 22A and a rod cover. 48A is provided with an exhaust switching valve 37A. According to this fluid pressure cylinder 10A, the thrust can be increased at the stroke end without providing a complicated lock mechanism. In addition, since no mechanical locking mechanism is required to connect the piston and the piston rod, it is less likely that misfits will occur against impacts in the axial direction, resulting in excellent reliability.

Further, in the fluid pressure cylinder 10A of the present embodiment, the diameter of the power boosting piston 22A can be made larger than the diameter of the working piston 20. As shown in FIG. Therefore, by increasing the diameter of the booster piston 22A, it is possible to reduce the diameter of the operating piston 20 while maintaining the thrust at the stroke end, thereby further reducing the consumption of high-pressure air.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention. stomach.

That is, in the above-described embodiment, the drive devices 120 and 120A of the fluid pressure cylinders 10 and 10A are arranged outside the fluid pressure cylinders 10 and 10A, but the present invention is not limited to this. . A part or all of the members constituting the drive devices 120 and 120A may be built in the cylinder body 12 .

Also, high-pressure fluid is sealed in the first pressure chamber 38 and the second pressure chamber 40 of the fluid pressure cylinder 10, the boosting piston 22 performs an operating stroke, and an additional thrust is generated from the operating piston 20 in the boosting process. You may

Claims (16)

a cylinder body (12) formed with a sliding hole (12a) extending in the axial direction;
a partition wall (26) separating the sliding hole into a head-side working cylinder chamber (14a) and an end-side boosting cylinder chamber (16a);
an actuating piston (20) disposed in the actuating cylinder chamber and partitioning the actuating cylinder chamber into a head-side first pressure chamber (38) and an end-side second pressure chamber (40);
an boost piston (22) arranged in the boost cylinder chamber and dividing the boost cylinder chamber into a head-side third pressure chamber (42) and an end-side fourth pressure chamber (44);
a piston rod (18) connected to the actuating piston and the boosting piston and extending through the partition wall to the end side;
A high-pressure fluid is enclosed in two adjacent pressure chambers among the first pressure chamber, the second pressure chamber, the third pressure chamber, and the fourth pressure chamber, and
While the working piston is positioned closer to the head than the predetermined position, high-pressure fluid is allowed to pass between the two pressure chambers. A boost switching mechanism (33) for blocking conduction of high-pressure fluid between the two pressure chambers and exhausting high-pressure fluid in one of the two pressure chambers,
hydraulic cylinder. 2. The fluid pressure cylinder according to claim 1, wherein high-pressure fluid is sealed in said second pressure chamber and said third pressure chamber,
The boost switching mechanism is
a communicating passage (34) communicating with the second pressure chamber and the third pressure chamber;
an exhaust passage (36) communicating with the second pressure chamber;
a conduction switching valve (35) that opens the communication passage while the working piston is positioned closer to the head than the predetermined position, and closes the communication passage when the working piston moves toward the end side of the predetermined position; ,
While the working piston is positioned closer to the head than the predetermined position, the exhaust path is closed, and when the working piston moves to the end side of the predetermined position, the exhaust path is opened to close the second pressure chamber. an exhaust switching valve (37) for exhausting high-pressure fluid;
A hydraulic cylinder having a 3. The fluid pressure cylinder according to claim 2, wherein said communication passage, said exhaust passage, said conduction switching valve and said exhaust switching valve are provided in said partition wall. 2. The fluid pressure cylinder according to claim 1, wherein high-pressure fluid is sealed in said third pressure chamber and said fourth pressure chamber,
The boost switching mechanism is
a communicating passage (35e) communicating with the third pressure chamber and the fourth pressure chamber;
an exhaust passage communicating with the fourth pressure chamber;
a conduction switching valve that opens the communication passage while the working piston is positioned closer to the head than the predetermined position, and closes the communication passage when the working piston moves toward the end side of the predetermined position;
While the working piston is positioned closer to the head than the predetermined position, the exhaust path is closed, and when the working piston moves to the end side of the predetermined position, the exhaust path is opened to close the fourth pressure chamber. an exhaust switching valve for exhausting high-pressure fluid;
A hydraulic cylinder having a 5. A fluid pressure cylinder according to claim 4, wherein said boosting piston is provided with said communication passage and said conducting switching valve. 6. The fluid pressure cylinder according to claim 5, further comprising a rod cover (48) for sealing an end portion of the fourth pressure chamber, wherein the rod cover covers the exhaust passage and the exhaust switching valve. hydraulic cylinder. 5. A fluid pressure cylinder according to claim 2 or 4, wherein said cylinder body has an adjustment port (32) communicating with said exhaust passage, said exhaust passage exhausting high pressure fluid through said adjustment port. pressure cylinder. 5. The fluid pressure cylinder according to claim 2 or 4, wherein said power boost switching mechanism causes said exhaust switching valve to open said exhaust passage after said conduction switching valve closes said communication passage. 9. The fluid pressure cylinder according to any one of claims 2 to 8, wherein one end of said conduction switching valve protrudes toward one of said two pressure chambers and the other end is inserted into said communication passage. and a conduction switching pin (35a), wherein the conduction switching pin (35a) is axially pressed in accordance with the displacement of the operating piston to close the communication passage. 9. The fluid pressure cylinder according to any one of claims 2 to 8, wherein the exhaust switching valve has a base end portion inserted into the exhaust passage to seal the exhaust passage, and a tip portion having a head portion. A fluid pressure cylinder having a detection pin (37a) protruding to the side, wherein the detection pin is pressed by the operating piston or the boosting piston and displaced toward the end side to release the sealing of the exhaust passage. 4. The fluid pressure cylinder according to claim 2 or 3, wherein the exhaust path is provided with a first check valve (52) that allows fluid to pass only in the direction of discharge and blocks fluid in the opposite direction. Hydraulic cylinder. 4. The fluid pressure cylinder according to claim 2 or 3, further comprising a replenishment channel (78) communicating with the second pressure chamber, through which fluid directed toward the second pressure chamber passes. Hydraulic cylinder provided with a second check valve (54) to allow. 8. The fluid pressure cylinder according to claim 7, further comprising an auxiliary flow path (76) communicating with said fourth pressure chamber and said adjustment port, wherein said auxiliary flow path extends from said fourth pressure chamber to said A hydraulic cylinder provided with a third check valve (56) which allows passage of fluid only in a direction towards the regulation port and blocks fluid in the opposite direction. 3. The fluid pressure cylinder according to claim 2, further comprising a drive device (120) connected to said first pressure chamber, said second pressure chamber and said fourth pressure chamber,
said drive device having a switching valve (102), a high pressure fluid supply (104), an exhaust port (106) and a fourth check valve (86);
in the first position of the switching valve, the first pressure chamber communicates with the high-pressure fluid supply source, and the fourth pressure chamber and the boost switching mechanism communicate with the exhaust port;
In the second position of the switching valve, the first pressure chamber communicates with the fourth pressure chamber via the fourth check valve, the first pressure chamber communicates with the exhaust port, and the second pressure chamber communicates with the exhaust port. a pressure chamber in communication with the high pressure fluid supply;
hydraulic cylinder. 5. The fluid pressure cylinder according to claim 4, further comprising a drive device (120A) connected to the first pressure chamber, the second pressure chamber and the fourth pressure chamber,
The driving device has a switching valve, a high pressure fluid supply, an exhaust port, and a fourth check valve,
in the first position of the switching valve, the first pressure chamber communicates with the high-pressure fluid supply source, and the fourth pressure chamber and the second pressure chamber communicate with the exhaust port;
In the second position of the switching valve, the first pressure chamber communicates with the second pressure chamber via the fourth check valve, the first pressure chamber communicates with the exhaust port, and the fourth pressure chamber communicates with the exhaust port. a pressure chamber in communication with the high pressure fluid supply;
hydraulic cylinder. 16. The fluid pressure cylinder according to claim 14, wherein a throttle valve (88) is provided between said first pressure chamber and said exhaust port.

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