Patent Description:
PTL <NUM> discloses a locking device including a first coil spring arranged in a case with its terminal end fixed to the case and its front end in a free condition. A locked rod is inserted through the inside of the first coil spring in the state of being fastened and locked with the spring force of the coil spring. A first unlocking actuator is arranged in the case for pushing/pulling the other end of the first coil spring to the direction of opening the coil spring to unlock it.

PTL <NUM> and PTL <NUM> disclose known examples of the locking device for rod that locks a rectilinearly movable rod, such as a piston rod of a fluid pressure cylinder, at a stop position.

These locking devices are configured such that a rod is inserted through a metallic locking member (brake member) shaped like the letter U or the letter C and the locking member clamps and thereby locks the rod at a stop position. In releasing the rod, a lock-release piston of a cylinder unit pushes open the locking member, and the locking member releases the rod from the locked state.

In such locking devices, the clamping force (locking force) of the locking member may be increased, for example, by changing the material or the thickness of the locking member and thereby increasing the elastic force, or by increasing the friction force at the clamping surfaces (surfaces to be in contact with the rod) of the locking member, or by providing a mechanism to urge the locking member in a clamping direction.

It is relatively easy to increase the elastic force of the locking member or to increase the friction force of the clamping surfaces. These methods, however, are limited in the amount of locking force to be increased and may not be suitable for a rod with a large thrust force.

In addition, providing the mechanism of urging the locking member in the clamping direction complicates the structure of the locking device.

Also <CIT>, <CIT> and <CIT> disclose locking devices according to the prior art.

A problem is to provide a locking device for rod that is simple in structure and can exert a large locking force when a rod is locked.

This problem is solved by a locking device according to claim <NUM>. Preferred embodiments are evident from the dependent claims.

In the present invention, the lids of the locking units may be formed as the single member elongated so as to cover all the casings of the locking units, whereby the single member lid has the single release port and has all the multiple communication channels that communicate the single release port with the release pressure chambers of the multiple locking units.

It is desirable that each casing have a first end at one end in an axis direction thereof and a second end opposite to the first end, and that annular stepped recesses with the same diameter be formed concentrically with the rod at the first end and at the second end, respectively. It is also desirable that a half portion and another half portion of the connection spacer in a thickness direction of the connection spacer engage mutually opposing stepped recesses of adjacent casings, respectively.

In addition, it is desirable that the connection spacer have an annular recess that is formed at a side surface of the connection spacer so as to surround the center hole and that the recess engage a protrusion formed at a side surface of the locking member.

In the present invention, it is also desirable that a detection member be attached to the release piston so as to be detectable from outside of the lid and that a sensor that detects the detection member be attached to the lid.

In this case, it is desirable that the detection member be configured such that when the release piston is at a locked position, the detection member protrudes out of the lid and when the release piston is at an unlocked position, the detection member is withdrawn into the lid. It is also desirable that the sensor be shaped like a recess as viewed in plan and disposed so as to surround the detection member in three directions when the detection member is protruding out of the lid, and that a height of the sensor be higher than a height of the detection member when the detection member protrudes out of the lid, whereby the sensor also serves as a safety member for preventing a wrong operation on the detection member.

The locking device according to the present invention can provide locking force proportional to the number of the locking units. The locking force becomes far larger than that of a known locking device equipped with a single locking unit. In addition, it is easy to obtain a locking device having a required amount of locking force simply by determining the number of the locking units on the basis of the thrust force of a rod.

<FIG> illustrate a first embodiment of a locking device according to the present invention. As illustrated in <FIG>, this locking device 1A is to be mounted, using brackets <NUM> or the like, on a body <NUM> of an apparatus, such as a fluid pressure cylinder, equipped with a rod R that moves rectilinearly in the axis L direction. The locking device 1A locks the rod R at a stop position. <FIG> and <FIG> illustrate a locked state of the locking device 1A in which a locking member <NUM> clamps and locks the rod R. <FIG> and <FIG> illustrate an unlocked state of the locking device 1A in which the locking member <NUM> releases the rod R.

As illustrated in <FIG> and <FIG>, the locking device 1A has multiple locking units <NUM> (two locking units <NUM> in the illustrated example). The locking units <NUM> are arrayed in a row along the rod R. Collars 7A and 7B for guiding the rod are disposed at one end and the other end of the row, and holding plates 8A and 8B are also disposed at one end and the other end of the row, respectively. The locking units <NUM> are sandwiched between the holding plates 8A and 8B and connected with each other by multiple bolts <NUM> that extend from the holding plate 8A at the one end through the locking units <NUM> and are screwed into the holding plate 8B at the other end.

Also referring to <FIG>, each locking unit <NUM> includes a metal casing <NUM> with the upper side being open and a metal-plate lid <NUM> that covers the upper side of the casing <NUM>. The rod R passes through the casing <NUM>.

Each locking unit <NUM> has an individual casing <NUM>, whereas the lid <NUM> is a single member that is elongated so as to cover all of the casings <NUM> of the locking units <NUM>. The single lid <NUM> is fixed to the multiple casings <NUM> with lid screws 5a.

Note that the casings <NUM> and the lid <NUM> may be made of the same metal or may be made of different metals. For example, the casings <NUM> are made of aluminum alloy, and the lid <NUM> may be made of steel.

The locking member <NUM> is accommodated in each casing <NUM>. The locking member <NUM> is a metal member shaped like the letter U or the letter C and has a pair of locking arms 6a that opposes each other. A rod insertion hole <NUM> is formed in the locking member <NUM> at a position where the base ends of the locking arms 6a are connected. The rod R is inserted through the rod insertion hole <NUM>.

A pair of the locking arms 6a of the locking member <NUM> are self-urged in directions to get closer to each other, which causes the locking arms 6a to clamp the rod R from both sides and thereby lock the rod R as illustrated in <FIG> and <FIG>.

As illustrated in the right locking unit <NUM> of <FIG>, a spiral groove 10a is formed at the inside surface of the rod insertion hole <NUM>. The spiral groove 10a serves as a path for discharging abrasion material or grease or the like adhered to the inside surface of the rod insertion hole <NUM> or to the outside surface of the rod R, thereby allowing them to escape.

A lock-release mechanism <NUM> is also formed inside each casing <NUM>. The lock-release mechanism <NUM> serves to displace the locking member <NUM> from a locked position for clamping the rod R (see <FIG> and <FIG>) to an unlocked position for releasing the rod R (see <FIG> and <FIG>). The lock-release mechanism <NUM> has a piston chamber <NUM> formed between the casing <NUM> and the lid <NUM>. The lock-release mechanism <NUM> includes a release piston <NUM> that is accommodated inside the piston chamber <NUM> so as to be movable in the up-down direction. The lock-release mechanism <NUM> also includes a wedge-like action portion 15a formed as part of the release piston <NUM> and a pair of needle rollers <NUM> that can be displaced so as to get closer to or get further away from each other. A release pressure chamber <NUM> is formed inside the piston chamber <NUM> between the upper surface of the release piston <NUM> and the lower surface of the lid <NUM>. The release pressure chamber <NUM> communicates, through a communication channel <NUM> formed inside the lid <NUM>, with a single release port <NUM> formed at a central portion of the upper surface of the lid <NUM>.

The release port <NUM> is formed where the release pressure chambers <NUM> of the adjacent locking units <NUM> are closest to each other. Accordingly, the two adjacent release pressure chambers <NUM> can communicate with the release port <NUM> through the shortest communication channels <NUM>.

In addition, the single release port <NUM> supplies a pressurized fluid to multiple release pressure chambers <NUM> using a single pipe connected to the release port <NUM>, which can make the piping simple.

As can be seen in <FIG>, the action portion 15a of the release piston <NUM> is formed of a member that is shaped so as to have decreasing thickness toward the lower end (tip end) thereof. The action portion 15a is joined, using a connection screw 15b, to a central portion of the release piston <NUM> at the lower surface thereof. The lower end of the action portion 15a enters between a pair of the needle rollers <NUM>. One side surface of the action portion 15a is thereby brought into contact with one needle roller <NUM>, and the other side surface thereof is brought into contact with the other needle roller <NUM>. The release piston <NUM> and the action portion 15a are made of a metal. The needle rollers <NUM> are also made of a metal.

Subsequently, in the state illustrated in <FIG> and <FIG>, a pressurized fluid, such as compressed air, is supplied through the release port <NUM> to the release pressure chamber <NUM>, which thereby lowers the release piston <NUM>. As a result, as illustrated in <FIG> and <FIG>, the wedge-like action portion 15a pushes open a pair of the needle rollers <NUM> in right-left directions, and the needle rollers <NUM> push open a pair of the locking arms 6a of the locking member <NUM> in the right-left directions. Thus, the locking arms 6a release the rod R. As a result, the rod R becomes displaceable in the axis L direction. Accordingly, the position to which the release piston <NUM> is lowered is referred to as a lock-release position (unlocked position) of the release piston <NUM>.

Members denoted by reference sign <NUM> are metallic roller-support bearings that are fixed to the inside surfaces of respective upper end portions of the locking arms 6a. The roller-support bearings <NUM> are provided to prevent the locking arms 6a from being damaged or worn down due to contact with the needle rollers <NUM>.

A recovery spring <NUM> that urges the release piston <NUM> upward is disposed between the lower surface of the release piston <NUM> and the upper surface of the locking member <NUM>. The recovery spring <NUM> raises the release piston <NUM> to the locked position as illustrated in <FIG> when the pressurized fluid is discharged from the release pressure chamber <NUM> in the state in which the pressurized fluid is supplied to the release pressure chamber <NUM> and the release piston <NUM> is lowered to the lock-release position as illustrated in <FIG>. As a result, a pair of the needle rollers <NUM> cease to push open the locking arms 6a, and the locking member <NUM> returns to the locked position by itself and the locking arms 6a lock the rod R.

The two locking units <NUM> do the same operation simultaneously. Accordingly, when the locking device 1A locks the rod R, the locking force is twice as large as that of a locking device equipped with only one locking unit <NUM>.

A pair of the needle rollers <NUM> are supported by a roller holder <NUM>. The roller holder <NUM> includes a cylindrically shaped trunk portion 22a and a flange 22b formed circumferentially around the upper end of the trunk portion 22a. The roller holder <NUM> is disposed inside the casing <NUM> concentrically with the release piston <NUM> at a position below the release piston <NUM>. Upper end portions 6b of respective locking arms 6a are fitted in the trunk portion 22a, and the needle rollers <NUM> are disposed between the upper end portions 6b. Horizontally elongated support holes 22c are formed at opposing positions in the circumferential wall of the trunk portion 22a, and one end portions and the other end portions of the needle rollers <NUM> are fitted in the respective support holes 22c so as to be able to move laterally in the support holes 22c. The width of the upper end portion 6b of each locking arm 6a in the axis L direction is smaller than the width of any other part of the locking arm 6a.

Moreover, the roller holder <NUM> is also displaceable in the up-down direction, and a compression spring <NUM> is disposed between the flange 22b and a stepped portion 4a formed at the casing <NUM>. Since the roller holder <NUM> is movable in the up-down direction, the needle rollers <NUM> are slightly lowered together with the roller holder <NUM> when the release piston <NUM> is lowered and the action portion 15a pushes open a pair of the needle rollers <NUM> as illustrated in <FIG>. This enables the needle rollers <NUM> to rotate readily and push open the locking arms 6a easily.

Note that when the release piston <NUM> is raised to the locked position, the compression spring <NUM> pushes the roller holder <NUM> upward to the initial position illustrated in <FIG>.

A pin-like detection member <NUM> is attached to the upper surface of the release piston <NUM> at the center thereof. The detection member <NUM> is slidably inserted into a detection hole <NUM> formed in the lid <NUM> with a sealing member <NUM> interposed therebetween. The detection member <NUM> is configured such that the end of the detection member <NUM> protrudes above, and also withdraws from, the upper surface of the lid <NUM> as the release piston <NUM> moves up and down. The base end of the detection member <NUM> is a mounting portion 26a shaped like a disc. The mounting portion 26a engages a recess <NUM> formed at the upper surface of the release piston <NUM>, and the detection member <NUM> is thereby fixed to the release piston <NUM>.

A sensor <NUM> for detecting the detection member <NUM> is disposed at the upper surface of the lid <NUM>. The sensor <NUM> is a transmission-type photoelectric sensor that includes a sensor head <NUM> having a phototransmitter 31a and a photodetector 31b and also includes a lead <NUM> through which detection signals are sent to a control unit (not illustrated). Detection light is emitted by the phototransmitter 31a to the photodetector 31b, and the sensor <NUM> detects the presence of the detection member <NUM> on the basis of the amount of light received by the photodetector 31b. In other words, when the release piston <NUM> is raised and present at the locked position, the detection member <NUM> protrudes above the upper surface of the lid <NUM> and blocks the detection light. Due to the photodetector 31b receiving a less amount of light, the sensor <NUM> detects that the locking unit <NUM> is in the locked state. On the other hand, when the release piston <NUM> is lowered and present at the lock-release position, the detection member <NUM> is also lowered into the inside of the lid <NUM>. Due to the photodetector 31b receiving an increased amount of light, the sensor <NUM> detects that the locking unit <NUM> is in the unlocked state.

The sensor <NUM>, however, may be a reflection-type photoelectric sensor. In this case, the phototransmitter and the photodetector are disposed side by side in the sensor head <NUM>, and the phototransmitter emits detection light toward the detection member <NUM>. The photodetector receives the light reflected by the detection member <NUM>. The reflected light is converted to an electrical signal, and the electrical signal is output to the lead. When the release piston <NUM> is raised and present at the locked position, the detection member <NUM> protrudes above the upper surface of the lid <NUM> and reflects the detection light. The sensor <NUM> thereby detects that the locking unit <NUM> is in the locked state. On the other hand, when the release piston <NUM> is lowered and present at the lock-release position, the detection member <NUM> is also lowered into the inside of the lid <NUM>. In this case, the detection member <NUM> does not reflect the detection light from the phototransmitter. The sensor <NUM> thereby detects that the locking unit <NUM> is in the unlocked state.

The sensor head <NUM> of the sensor <NUM> is shaped like a recess as viewed in plan so as to surround the detection member <NUM> in three directions. The height of the sensor head <NUM> is higher than the height of the detection member <NUM> when the detection member <NUM> protrudes above the lid <NUM>. This prevents the detection member <NUM> from being pressed by a finger or a tool by mistake and from being switched to the unlocked state. Accordingly, the sensor <NUM> also serves as a safety member for preventing a wrong operation on the locking unit <NUM>.

A ring-shaped connection spacer <NUM> connects one and another locking units <NUM> with each other. As illustrated in <FIG> and <FIG>, the connection spacer <NUM> has a center hole <NUM> through which the rod R is inserted. The connection spacer <NUM> has one side surface and the other side surface in the thickness direction (in the axis L direction), and annular recesses <NUM> are formed concentrically with the center hole <NUM> at the one and the other side surfaces, respectively. The inside diameter of the center hole <NUM> is slightly larger than the outside diameter of the rod R. The recesses <NUM> at the one and the other side surfaces have the same diameter and depth.

Annular stepped recesses <NUM> are formed, in the casing <NUM> of each locking unit <NUM>, respectively at a first end 4b and a second end 4c of the casing <NUM> that are opposite to each other in the axis L direction. The stepped recesses <NUM> have the same diameter and are disposed concentrically with each other and also with the rod R. The stepped recesses <NUM> at the first end 4b and the second end 4c have the same depth, which is equal to a half of the thickness of the connection spacer <NUM>.

The casings <NUM> of adjacent locking units <NUM> are disposed such that the first end 4b of one casing <NUM> opposes the second end 4c of the other casing <NUM>. One half portion and the other half portion of the connection spacer <NUM> in the thickness direction are fitted in respective stepped recesses <NUM> that oppose the connection spacer <NUM>.

Protrusions 6c are formed at respective side surfaces of the locking member <NUM>. A protrusion 6c engages a corresponding recess <NUM> of a connection spacer <NUM>. Thus, the connection spacer <NUM> supports an end portion of the locking member <NUM>.

The connection spacer <NUM> enables adjacent casings <NUM> to be positioned accurately with respect to each other and also to the rod R. Accordingly, multiple locking units <NUM> can be connected easily with high accuracy.

Each of the collars 7A and 7B has a body 7a shaped cylindrically, a ring-like engagement portion 7b formed at an end of the body 7a, a guide hole 7c through which the rod R is inserted, and a recess 7d formed so as to surround the guide hole 7c. The outside diameter of the engagement portion 7b is the same as the outside diameter of the connection spacer <NUM>. A bushing <NUM> and a rod packing <NUM> are disposed inside the guide hole 7c so as to come into contact with the circumferential surface of the rod R. The engagement portion 7b of the collar 7A engages the stepped recess <NUM> of the first end 4b of the locking unit <NUM> disposed near the one end (left side in <FIG>) of the locking device 1A. The engagement portion 7b of the collar 7B engages the stepped recess <NUM> of the second end 4c of the locking unit <NUM> disposed near the other end (right side in <FIG>) of the locking device 1A. Protrusions 6d formed at the side surfaces of the locking members <NUM> are fitted in the corresponding recesses 7d of the collars 7A and 7B.

The holding plates 8A and 8B are rectangularly shaped plates that are disposed at the one and the other ends of the locking device 1A, respectively. The holding plates 8A and 8B have respective lead-out holes 8a through which the bodies 7a of the collars 7A and 7B pass outward.

The holding plate 8A disposed at the one end (left side in <FIG>) of the locking device 1A has throughholes through which the bolts <NUM> are inserted and counterbores for accommodating the heads of the bolts <NUM> each having a hexagonal hole. The number of the throughholes and the counterbores are the same as that of the bolts <NUM>. The holding plate 8B disposed at the other end (right side in <FIG>) of the locking device 1A has screw holes for receiving the male threads formed at respective ends of the bolts <NUM>. The number of the screw holes are the same as that of the bolts <NUM>.

Multiple casings <NUM> are connected with each other with the bolts <NUM> that are inserted from the holding plate 8A through throughholes 4d formed in the casing <NUM> of each locking unit <NUM> and screwed into the screw holes formed at the holding plate 8B.

The connection structure using the bolts <NUM> is generally known, and detailed illustration thereof is omitted.

The single lid <NUM> is fixed, using lid screws 5a, onto the upper side of the casings <NUM> that are connected with each other as described above. Thus, the locking device 1A is formed.

The lid <NUM> is detachable from the multiple casings <NUM>, and the number of the locking units <NUM> can be increased or decreased. When changing the number of locking units <NUM>, the lid <NUM> and the bolts <NUM> are replaced with ones having a length that fits the number of the locking units <NUM>.

Note that the brackets <NUM> for fixing the locking device 1A to the body of an apparatus are attached to the holding plates 8A and 8B.

As a second embodiment of the locking device 1A, <FIG> illustrates a locking device 1B that is connected directly to a fluid pressure cylinder <NUM>. In the locking device 1B according to the second embodiment, the holding plate 8B and the collar 7B attached to the right end of the locking device 1A of the first embodiment are removed. Instead, an engagement portion 53a formed at a rod cover <NUM> of the fluid pressure cylinder <NUM> is fitted in the stepped recess <NUM> of the second end 4c of the right locking unit <NUM>. The male threads formed at the ends of the bolts <NUM> (see <FIG>) are screwed into screw holes formed in the rod cover <NUM>, and the locking device 1B is thereby attached to the rod cover <NUM>. In this case, it is not necessary to use the brackets <NUM> that are used for the locking device 1A of the first embodiment.

Other configurations and advantageous effects of the locking device 1B are substantially the same as those of the locking device 1A of the first embodiment. Major elements of the locking device 1B are the same as those of the locking device 1A and are denoted by the same reference signs, and detailed descriptions thereof are omitted.

<FIG> illustrate a locking device 1C according to a third embodiment. The locking device 1C is different from the locking device 1A of the first embodiment in that the locking device 1C has three locking units <NUM>. The structure of each locking unit <NUM> and the configuration of connection, however, are the same as those of the locking unit <NUM> of the locking device 1A. Major elements of the locking device 1C are the same as those of the locking device 1A and are denoted by the same reference signs, and the descriptions thereof are omitted.

The locking force of the locking device 1C of the third embodiment is <NUM> times as large as that of the locking device 1A of the first embodiment and <NUM> times as large as that of a locking device equipped with only one locking unit <NUM>.

Note that although the single lid <NUM> is attached to multiple locking units <NUM> of each of the locking devices 1A, 1B, and 1C of the above embodiments, separate lids <NUM> may be provided for different locking units <NUM>. In this case, the release port <NUM> is formed at each one of the lids <NUM>.

Claim 1:
A locking device for a rod, that is configured to lock a rod (R) movable rectilinearly in an axis (L) direction at a stop position, the locking device (1A, 1B, 1C) comprising:
multiple locking units (<NUM>) that are configured to be arrayed along the rod (R) and connected to each other, wherein
the locking units (<NUM>) each have an individual casing (<NUM>) through which the rod (R) is insertable and a lid (<NUM>) that covers the casing (<NUM>), the casing (<NUM>) accommodates a locking member (<NUM>) that is configured to clamp and thereby lock the rod (R) and a release piston (<NUM>) that is configured to unlock the locking member (<NUM>) by receiving fluid pressure,
a release pressure chamber (<NUM>) is formed between the casings (<NUM>) and the lid (<NUM>) so as to apply the fluid pressure to the release piston (<NUM>);
wherein the lids (<NUM>) of the locking units
- are formed as a single member lid elongated so as to cover all the casings (<NUM>) of the locking units
or
- are alternatively provided as separate lids for the different locking units;
wherein
- a single release port (<NUM>) that is configured to supply and discharge a pressurized fluid and communication channels (<NUM>) that communicate the release port (<NUM>) with the respective release pressure chambers (<NUM>) are formed in the single member lid (<NUM>)
or
- alternatively a release port (<NUM>) that is configured to supply and discharge a pressurized fluid and a communication channel (<NUM>) that communicates the release port (<NUM>) with the release pressure chamber (<NUM>) are formed at each one of the separate lids (<NUM>);
and wherein
a ring-like connection spacer (<NUM>) is disposed between the casings (<NUM>) of adjacent locking units (<NUM>) and is configured to be concentric with the rod (R), the connection spacer (<NUM>) connects the casings (<NUM>) of the adjacent locking units (<NUM>) with each other, and
the rod (R) is insertable through a center hole (<NUM>) of the connection spacer (<NUM>).