Patent Description:
For example, patent literatures <NUM> and <NUM> respectively disclose a rotary clamp that fixes a clamp object by turning and lowering a clamp arm. In the rotary clamp, a clamp rod (output member) provided with the clamp arm is inserted in a housing so as to be movable in a vertical direction and so as to be rotatable around an axis. The rotary clamp is provided with a motion detection device that detects an operation of the clamp rod. In the rotary clamp of patent literature <NUM>, the position of the clamp rod is detected by integrally attaching an operation unit to one end part of the clamp rod and by opening and closing inlet holes for pressure fluid supply provided at different positions in the vertical direction. In patent literature <NUM>, the up and down movement of the clamp rod is once converted into movement in a radial direction by the engaging ball, and further, a structure that converts the radial movement of the engaging ball into the up and down movement of a valve body is provided at the one end part of the clamp rod. The valve body opens and closes an opening of pressurized air passage provided toward the vertical direction. <CIT>, which forms the basis for the preamble of claim <NUM>, discloses a rod position detector for detecting a position of a clamp rod. <CIT> discloses a fluid pressure cylinder for detecting the position of a piston member via air pressure that is changed over by a valve mechanism.

In the motion detection device of the patent document <NUM>, when the operation unit opens and closes the inlet hole, the operation unit slides around the periphery of the opening of the inlet hole, so that prolonged use may affect the performance of closing the inlet hole. On the other hand, in the motion detection device of the patent document <NUM>, the opening of the pressurized air passage can be opened and closed by the up and down movement of the valve body without sliding as in the patent document <NUM>. However, the valve body is not integrated with the clamp rod, and a mechanical element that transmits the movement of the clamp rod intervenes in the middle, so that there is a problem that it does not necessarily detect the movement of the clamp rod itself. For example, in the patent literature <NUM>, when the valve body causes malfunction due to breakage of the valve body or the like, even if the clamp rod operates normally, it is erroneously detected that the valve body is abnormal.

The aim of the present invention is to directly and accurately detect the movement of the output member itself of the rotary clamp.

In the present invention, which is defined in claim <NUM>, a cylinder having an output member that is moved up and down by a pressure fluid is accommodated in a cylinder hole provided in a housing. The cylinder includes a first valve chamber provided between a lower wall of the housing and the output member, a second valve chamber with the output member hollowed out and opened to the first valve chamber side, and a valve rod protruding from the lower wall to be inserted into the second valve chamber. The valve rod is provided with a valve rod passage opened toward the second valve chamber. Between the valve rod and the second valve chamber, a seal section is provided on an outer peripheral wall side of the valve rod or on an inner peripheral wall side of the second valve chamber. When the valve rod and the second valve chamber move relative to each other, a compressed air flow passage formed between the first valve chamber and the second valve chamber is configured so as to have a close region sealed by the seal section and an open region opened from the seal. Compressed air is supplied from one end of the compressed air flow passage, and the other end of the compressed air flow passage is opened to the outside air.

The motion detection device used in the present invention is configured to avoid sliding on the inlet hole as much as possible although the point that the operation unit is integrally provided to one end part of the output member or clamp rod is the same as that shown in the patent literature <NUM>. Therefore, when the motion detection device is used for a long period of time, it is possible to reduce wear on the outer peripheral wall of the operation unit or the inner peripheral wall of the inlet hole, and the size of the sliding gap formed between the operation unit and the inlet hole can be maintained for a long time. Thus, the movement of the clamp rod can be accurately detected. In addition, in that the operation unit directly opens and closes the valve, the movement of the output member can be detected without interposing the mechanical element for transmitting the movement of the clamp rod as disclosed in the patent literature <NUM> in the middle.

The present invention includes a first valve chamber provided on a lower side of an output member, a second valve chamber with the output member hollowed out and opened to the first valve chamber side along an axis, and a valve rod protruding from a lower wall of the first valve chamber to be inserted into the second valve chamber. The valve rod is provided with a valve rod passage having one end opened to the second valve chamber. The valve rod and the second valve chamber are relatively moved by the up and down movement of the output member. In this way, a compressed air flow passage through which the compressed air passes is formed between the first valve chamber and the valve rod passage. The compressed air is supplied to one end side (the first valve chamber or the valve rod passage) of the compressed air flow passage, and is discharged to the outside air from the other end side (the valve rod passage or the first valve chamber) of the compressed air flow passage. A seal section for closing the movement of the compressed air is provided between the valve rod and the second valve chamber. A gap between the valve rod and the second valve chamber is formed so that there exist a close region sealed by the seal section and an open region released from the seal when the valve rod and the second valve chamber move relative to each other. In this embodiment, the compressed air flow passage is composed of the gap.

In the open region released from the seal, a region having a different cross-sectional area of the gap maybe provided so as to generate a different pressure loss when the compressed air passes between the valve rod and the second valve chamber in a movement process when the valve rod and the second valve chamber move relative to each other.

A bypass passage leading from the first valve chamber to the valve rod passage is provided on the close region to be sealed, and a predetermined pressure loss by the bypass passage may be generated in the up and down regions of the position where the bypass passage is provided.

When referring to "up" or "down" in this specification, it does not indicate a direction of gravity, the direction in which the output member is drawn into the housing is called "down", and the direction in which the output member is pulled out of the housing is "up".

The first embodiment will be described with reference to <FIG>.

First, the overall structure of the rotary clamp will be described with reference to <FIG>. A housing <NUM> is fixed to a table T as a fixing base by a plurality of bolts (not shown). The housing <NUM> includes an upper wall (a distal wall) 1a, a lower wall (a proximal wall) 1b, a barrel wall 1c extending in a vertical direction, and a cylinder hole <NUM> formed inside the barrel wall 1c.

A part of an output member <NUM> penetrates outside the housing <NUM> through a cylindrical hole <NUM> formed in the upper wall 1a of the housing <NUM>. The output member <NUM> is hermetically inserted into the cylindrical hole <NUM> so as to be rotatable around an axis C and so as to be movable in the vertical direction (the direction of the axis C). An arm <NUM> is fixed to an upper end portion of the output member <NUM>.

The output member <NUM> includes a rod body 5a, a piston portion 5b having a larger diameter than the rod body 5a, and a lower rod 5c, which are formed in order from the upper side. The lower rod 5c is slidably inserted into a cylindrical hole (bottomed insertion hole) 10a of a support cylinder <NUM> that forms a part of the lower wall 1b of the housing <NUM>.

A rotary mechanism <NUM> is provided between the lower rod 5c of the output member <NUM> and the upper part of the inner wall of the cylindrical hole 10a of the support cylinder <NUM>. The rotary mechanism <NUM> includes a guide groove <NUM> and a ball (engaging tool) <NUM>. The guide groove <NUM> is formed by connecting a spiral rotary groove <NUM> and a rectilinear groove <NUM> upward. The ball <NUM> is inserted into the guide groove <NUM>. The ball <NUM> is rotatably supported by a support hole <NUM> provided on the inner wall of the support cylinder <NUM>. A sleeve <NUM> is rotatably fitted around the axis. A V-shaped groove <NUM> is formed on the inner peripheral surface of the sleeve <NUM>, and the ball <NUM> can roll at two points above and below the V-shaped groove <NUM>.

The support cylinder <NUM> is prevented from rotating around the barrel wall 1c of the housing <NUM> through a positioning pin <NUM> extending in the vertical direction to adjust the circumferential position (phase) of the output member <NUM> with respect to the housing <NUM>.

A clamp chamber <NUM> is provided between the piston portion 5b and the upper wall 1a of the housing <NUM>. An unclamp chamber <NUM> is provided between the piston portion 5b and the lower wall 1b of the housing <NUM>. Pressure fluid for clamping (pressure oil, compressed air, etc.) is supplied to and discharged from the clamp chamber <NUM> through a supply / discharge path <NUM> formed in the upper wall 1a of the housing <NUM>. Further, pressure fluid for unclamping is supplied to and discharged from the unclamp chamber <NUM> through another supply / discharge path <NUM> formed in the barrel wall 1c of the housing <NUM>.

The rotary clamp illustrated in <FIG> is in an unclamp state. The pressure fluid is discharged from the clamp chamber <NUM>, and the pressure fluid is supplied to the unclamp chamber <NUM> through the supply / discharge path <NUM>. The output member <NUM> is at the upper limit position. When switching to the clamp state, the pressure fluid is discharged from the unclamp chamber <NUM> through the supply / discharge path <NUM>, and the pressure fluid is supplied to the clamp chamber <NUM> through the supply / discharge path <NUM>. When the piston portion 5b moves downward, the output member <NUM> descends while being turned clockwise in plane view along the rotary groove <NUM>. Subsequently, the output member <NUM> descends straight along the straight groove <NUM> to be in a clamp state. When switching the rotary clamp from the clamp state to the unclamp state, if the pressure fluid in the clamp chamber <NUM> is discharged and the pressure fluid is supplied to the unclamp chamber <NUM>, the output member <NUM> rises straight and then turns.

The lower wall 1b is provided with a cylindrical hole 10a into which the lower rod 5c constituting the lower side of the output member <NUM> is inserted. The cylindrical hole 10a is a bottomed hole having a bottom 10b. A motion detection device <NUM> includes a first valve chamber <NUM> provided between the bottom 10b of the cylindrical hole 10a and the undersurface 5d of the lower rod 5c, and a housing passage <NUM> provided on the lower wall 1b and supplying compressed air to the first valve chamber <NUM>, a second valve chamber <NUM> having the lower rod 5c hollowed open downward along the axis C, a valve rod 10c protruding from the bottom 10b to be inserted into the second valve chamber <NUM>, and a valve rod passage 10d leading the second valve chamber <NUM> to the outside air by penetrating through a top section of the valve rod 10c toward the second valve chamber <NUM>. It is desirable that the opening installation position of the housing passage <NUM> that opens to the first valve chamber <NUM> is a position that does not interfere with the operation of the lower rod 5c. As described above, in the present embodiment, one end of the compressed air flow passage formed between the first valve chamber <NUM> and the valve rod passage 10d is on the first valve chamber <NUM> side.

The second valve chamber <NUM> can be divided into a first region <NUM>, a second region <NUM>, and a third region <NUM> in order from bottom to top depending on the inner diameter of the inner peripheral wall 23a. The second region <NUM> has the smallest diameter, and the third region <NUM> has the largest diameter. The first region <NUM> has a diameter intermediate between the two. A seal section (O-ring) <NUM> is provided around the top section of the valve rod 10c. When the valve rod 10c and the second valve chamber <NUM> move relative to each other along the axis C, a gap (the cross-sectional area of the gap around the axis C, hereinafter simply referred to as "gap") between the outer peripheral wall 10e of the valve rod 10c at the position of the seal section <NUM> and the inner peripheral wall 23a of the second valve chamber <NUM> is changed. The outer peripheral side of the seal section <NUM> with respect to the axis C slightly protrudes radially outward from the outer peripheral wall 10e of the valve rod 10c. In the first region <NUM>, the seal section <NUM> is slightly separated from the inner peripheral wall 23a of the second valve chamber <NUM>. In the second region <NUM>, the seal section <NUM> is in contact with the inner peripheral wall 23a of the second valve chamber <NUM>, and an effect of sealing the compressed air is exhibited (validated). In the third region <NUM>, the seal section <NUM> is separated from the inner peripheral wall 23a of the second valve chamber <NUM>. On the other hand, in the first region <NUM> and the third region <NUM>, an effect of the seal section <NUM> for sealing the compressed air is invalidated.

Next, the operation of the motion detection device <NUM> will be described. The compressed air supplied from the housing passage <NUM> is guided into the first valve chamber <NUM>. In the unclamp state in <FIG>, a throttle passage (referred to as "throttle passage <NUM>") is formed between the seal section <NUM> in the first region <NUM> and the second valve chamber <NUM>, and the compressed air of the first valve chamber <NUM> is guided to the valve rod passage 10d through the throttle passage <NUM>.

<FIG> shows the rotary clamp at the time of transition from the unclamp state to the clamp state. When the lower rod 5c descends and the seal section <NUM> reaches the second region <NUM>, the flow passage between the first valve chamber <NUM> and the valve rod passage 10d is shut off.

In the clamp state shown in <FIG>, the lower rod 5c further descends, and the seal section <NUM> reaches the third region <NUM>. At this time, a flow passage <NUM> is formed between the seal section <NUM> and the second valve chamber <NUM>, and the compressed air in the housing passage <NUM> is discharged outside through the flow passage <NUM> and the valve rod passage 10d. The cross-sectional area of the gap through which the compressed air passes differs between the throttle passage <NUM> and the flow passage <NUM>, and the cross-sectional area of the flow passage <NUM> is larger than that of the throttle passage <NUM>. Therefore, the pressure loss from the housing passage <NUM> to the valve rod passage 10d is different between the case where the gas flows through the throttle passage <NUM> and the case where the gas flows through the flow passage <NUM>. In the present embodiment, in case of detecting by providing with a pressure sensor (not shown) for the housing passage <NUM>, when the detection pressure when the seal section <NUM> is present in the second region <NUM> is <NUM> MPa, the pressure is <NUM> MPa in the unclamp state of the first region <NUM> and <NUM> MPa in the clamp state of the third region <NUM> (back pressure is atmospheric pressure). The position of the output member <NUM> can be detected by detecting the pressure with the pressure sensor.

In the present embodiment, the second region <NUM> in which the second valve chamber <NUM> contacts the seal section <NUM> is provided in the middle, so that the detection value of the pressure sensor can be greatly changed when the seal section <NUM> moves from the first region <NUM> to the second region <NUM> or from the second region <NUM> to the third region <NUM>. In addition, since the second valve chamber <NUM> has no opening in the middle of the height and the seal section <NUM> does not slide through such an opening, so that the seal section <NUM> has little effect on the sealing performance. Further, since the seal section <NUM> is in contact with the inner peripheral wall 23a of the second valve chamber <NUM> only when the clamp state is changed, and is present in the first region <NUM> or the third region <NUM> during most of the normal time and not in a state of being compressed and deformed, the deterioration of the seal performance is small. In the first region <NUM>, the output member <NUM> turns around the axis C. At this time, since the seal section <NUM> is separated from the valve rod 10c, wear and breakage of the seal section <NUM> due to the rotary movement are prevented.

In the above embodiment, although the second valve chamber <NUM> is divided into the first region <NUM>, the second region <NUM>, and the third region <NUM> in order from bottom to top according to the inner diameter, the order of the inner diameter may be different. For example, if the diameter is reduced in order from bottom to top, there is an advantage that the processing of the second valve chamber <NUM> is easy.

<FIG> shows another configuration example of a motion detection device <NUM>. A second valve chamber <NUM> of the motion detection device <NUM> is divided into a first region <NUM>, a second region <NUM>, and a third region <NUM> in order from bottom to top by its inner diameter similarly to the second valve chamber <NUM> of the first embodiment. The second region <NUM> has the largest diameter, the third region <NUM> has the smallest diameter, and the first region <NUM> has an intermediate diameter. Other configurations are the same as in the first embodiment.

Next, the operation of the motion detection device <NUM> will be described. In the unclamp state of <FIG>, the compressed air in a first valve chamber <NUM> is guided to a valve rod passage 110d through a gap between a seal section <NUM> and the second valve chamber <NUM> in the first region <NUM>. As shown in <FIG>, when the lower rod 5c descends and the seal section <NUM> reaches the second region <NUM>, a gap between the first valve chamber <NUM> and the valve rod passage 110d becomes larger and the pressure loss is reduced compared to the case of the first region <NUM>.

In the clamp state of <FIG>, although the seal section <NUM> has reached the third region <NUM>, the gap between the seal section <NUM> and the second valve chamber <NUM> is closed. In this embodiment, the pressure detected by a pressure sensor (not shown) provided to the housing passage <NUM> is the highest when the position of the seal section <NUM> is in the third region <NUM>, and the next is when the seal section <NUM> is present in the first region <NUM>. When the seal section <NUM> is in the second region <NUM>, the pressure detected by the pressure sensor becomes the lowest. In this embodiment, in the second region <NUM>, since the seal section <NUM> does not contact with the inner peripheral wall 123a of the second valve chamber <NUM>, the seal section <NUM> can be prevented from being slid while the output member <NUM> is descending.

<FIG> illustrates a configuration example of a motion detection device <NUM> according to the third embodiment. A second valve chamber <NUM> of the motion detection device <NUM> is divided into a first region <NUM>, a second region <NUM>, and a third region <NUM> in order from bottom to top by its inner diameter, similarly to the second valve chamber <NUM> of the second embodiment. The second region <NUM> has the largest diameter, the third region <NUM> has the smallest diameter, and the first region <NUM> has an intermediate diameter. On the other hand, a valve rod 210c is composed of an elastic body. The valve rod 210c has a seal section <NUM> with an enormous diameter around the top of the head, and therefore, the present example differs from the examples described so far in that the seal section <NUM> is not a separate member made from an O-ring. In the unclamp state shown in <FIG>, the compressed air in the first valve chamber <NUM> is guided to the valve rod passage 210d through a gap between the seal section <NUM> and the second valve chamber <NUM> in the first region <NUM>. As shown in <FIG>, when the lower rod 5c descends and the seal section <NUM> reaches the second region <NUM>, a gap between the inner peripheral wall 223a of the second valve chamber <NUM> and the valve rod 210c becomes larger and the pressure loss is reduced compared to the case of the first region <NUM>.

In the clamp state shown in <FIG>, although the seal section <NUM> has reached the third region <NUM>, the gap between the seal section <NUM> and the second valve chamber <NUM> is closed. In this embodiment, the pressure detected by the pressure sensor is the highest when the position of the seal section <NUM> is in the third region <NUM>, and it becomes the second highest when the seal section <NUM> is in the first region <NUM>. When the seal section <NUM> is in the second region <NUM>, the pressure detected by the pressure sensor becomes the lowest.

In the first embodiment, the second valve chamber <NUM> was divided into the first region <NUM>, the second region <NUM>, the third region <NUM>, and the like in order from bottom to top according to its inner diameter, and the pressure loss was changed or the communication to the valve rod passage 10d was closed depending on the position of the seal section <NUM> of the valve rod 10c. In this embodiment, as shown in <FIG>, the outer diameter on the valve rod 310c side is changed in three steps from the bottom, namely, a first region <NUM>, a second region <NUM>, and a third region <NUM>. Here, the second region <NUM> has the smallest outer diameter, the third region <NUM> has the largest outer diameter, and the first region <NUM> has an intermediate outer diameter. A seal section <NUM> is provided on an inner peripheral wall 323a near the outlet on the second valve chamber <NUM> side.

In the unclamp state shown in <FIG>, a gap between the first valve chamber <NUM> and the second valve chamber <NUM> is closed by the third region <NUM> and the seal section <NUM>. As shown in <FIG>, when the lower rod 5c descends and the seal section <NUM> reaches the second region <NUM>, a gap is generated between the second valve chamber <NUM> and the valve rod 310c.

In the clamp state shown in <FIG>, the seal section <NUM> has reached the first region <NUM>. A gap between the seal section <NUM> and the valve rod 310c is smaller than the second region <NUM>. At the position of the second region <NUM>, the gap with the seal section <NUM> may be referred to as a simple flow passage in relation to another passage, and it is the first region <NUM> that is referred to as a throttle passage. These have different cross sections of the gap, and pressure loss is smaller in the flow passage than in the throttle passage.

The shape of the inner peripheral wall 323a of the second valve chamber <NUM> and the shape of the outer peripheral wall 310e of the valve rod 310c may be designed with an outer diameter so that the pressure loss is different depending on the position of the lower rod 5c, or may be provided with the seal section <NUM> that shuts off the gap between the first valve chamber <NUM> and the rod passage 310d on the second valve chamber <NUM> side or the valve rod 310c side.

<FIG> shows a configuration example of the motion detection device according to the fifth embodiment.

Although the first embodiment is an example wherein regions having different cross sections of the gap were provided so as to generate different pressure losses when the compressed air passes through between the valve rod 10c and the second valve chamber <NUM> when the valve rod 10c and the second valve chamber <NUM> relatively move in a region where the closing by the seal section <NUM> is invalid, the present embodiment is an example wherein a bypass passage <NUM> leading from the first valve <NUM> to the valve rod passage 410d is provided in a region where the closing by the seal section <NUM> is effective, and a predetermined pressure loss due to the bypass passage <NUM> occurs in the upper and lower regions of the position where the bypass passage <NUM> is provided.

In the present embodiment, the valve rod 410c is divided into a first region <NUM> and a second region <NUM> by its outer diameter. The first region <NUM> has a smaller outer diameter than the second region <NUM>, and a gap is formed between a seal section provided on an inner peripheral wall 423a side of a second valve chamber <NUM> and an outer periphery of a valve rod.

In the second region, an outer peripheral wall of a valve rod 410c contacts the seal section <NUM> provided on the inner peripheral wall 423a side of the second valve chamber <NUM>. In the middle of the height of the second region, there is the bypass passage <NUM> penetrating from the outer peripheral wall of the valve rod 410c to the valve rod passage 410d.

In the unclamp state shown in <FIG>, the seal section <NUM> provided on the inner peripheral wall of the second valve chamber <NUM> is located above the bypass passage <NUM> in the second region <NUM>. Although the compressed air in the first valve chamber <NUM> is prevented from entering the second valve chamber <NUM> side by the seal section <NUM>, the compressed air is guided to the valve rod passage 410d through the bypass passage <NUM>. As shown in <FIG>, when the lower rod 5c descends and the seal section <NUM> reaches the second region <NUM> below the bypass passage <NUM>, the first valve chamber <NUM> cannot be interconnected to the valve rod passage 410d through the bypass passage <NUM> to close between the first valve chamber <NUM> and the valve rod passage 410d.

In the clamp state shown in <FIG>, the seal section <NUM> reaches the first region <NUM>. In the first region <NUM>, the valve rod 410c is not in contact with the seal section <NUM>, so that the sealing performance of the seal section <NUM> is invalidated, and the first valve chamber <NUM> and the second valve chamber <NUM> communicate through the gap between the outer peripheral wall 410e and the inner peripheral walls 423a. Further, since the outer diameter of the valve rod 410c in the second region <NUM> is smaller than the inner diameter of the second valve chamber <NUM>, the compressed air in the first valve chamber <NUM> reaches the valve rod passage 410d opened at the top of the valve rod 410c. At this time, by setting the hole diameter of the bypass passage <NUM> so that the pressure loss from the first valve chamber <NUM> to the valve rod passage 410d is smaller than the pressure loss when passing through the bypass passage <NUM>, the unclamp state in <FIG> and the clamp state in <FIG> can be distinguished by the detection value of a pressure sensor (not shown).

In this embodiment, although the seal section <NUM> slides on the bypass passage <NUM>, since the hole diameter of the bypass passage <NUM> may be smaller than the opening for supplying the compressed air, the hole diameter of the bypass passage <NUM> has little effect on the performance of the seal section <NUM>. Further, by inserting the spacer 427b on the side of the seal section <NUM> that is contact with the valve rod 410c as a double structure of an elastic body 427a and a spacer 427b with a low coefficient of friction, the effect on the performance of the seal section <NUM> is further reduced.

<FIG> shows a configuration example of a motion detection device <NUM> according to the sixth embodiment, that does not fall under the scope of the claims. In the sixth embodiment, a sheath chamber <NUM> in which the lower rod 5c is opened in a hollow shape downward along the axis C does not have a function as a valve chamber through which compressed air flows. The sheath chamber <NUM> provides a bag-shaped space in which a mere valve rod 510c can be inserted and compressed air cannot leak. On the other hand, the bypass passages 40a, 40b are provided so as to lead from the first valve chamber <NUM> to the valve rod passage 510d. The bypass passages 40a, 40b are set up and down, in which a predetermined pressure loss is caused by blocking all or one of the bypass passages 40a, 40b from the communication with the first valve chamber <NUM> at the position of the seal section <NUM> by the up and down movement of the lower rod 5c.

In this embodiment, the valve rod 510c is divided into a first region <NUM>, a second region <NUM>, and a third region <NUM> from bottom to top depending on the positions of the bypass passages 40a, 40b. The first region <NUM> is below the bypass passage 40b, the second region <NUM> is between the bypass passage 40a and the bypass passage 40b, and the second region <NUM> is above the bypass passage 40a. The bypass passages 40a, 40b penetrate from the outer peripheral wall of the valve rod 510c to the valve rod passage 510d. The seal section <NUM> provided at the inlet of the sheath chamber <NUM> is to block direct communication between the first valve chamber <NUM> and the sheath chamber <NUM>. The seal section <NUM> has a double structure of an elastic body 527a and a spacer 527b with a low coefficient of friction.

In the unclamping state shown in <FIG>, the seal section <NUM> is located in a third region <NUM> above the bypass passage 40a. The compressed air in a first valve chamber <NUM> is guided to a valve rod passage 510d through the bypass passages 40a, 40b. As shown in <FIG>, when the lower rod 5c descends and the seal section <NUM> reaches the second region <NUM>, the bypass passage 40a cannot communicate with the first valve chamber <NUM> and the valve rod passage 510d, and the communication state is established only by the bypass passage 40b.

In the clamp state shown in <FIG>, the seal section <NUM> reaches the first region <NUM>. In the first region <NUM>, neither of the bypass passages 40a, 40b can communicate with the first valve chamber <NUM> and the valve rod passage 510d. By providing the bypass passages 40a, 40b above and below the valve rod 510c, the pressure loss is changed by changing the number of bypass passages 40a, 40b that communicate with the first valve chamber <NUM> and the valve rod passage 510d. This pressure change can be distinguished by a detection value of a pressure sensor (not shown). In the present embodiment, although there are two bypass passages 40a, 40b, a plurality of bypass passages may be provided. In the present embodiment, although the valve rod passage 510d provided in the length direction of the valve rod 510c opens toward the sheath chamber <NUM>, if there is another passage that leads the air in the sheath chamber <NUM> to the outside air, there is no need to open the sheath chamber <NUM> because the valve rod passage 510d does not play the role. In the present embodiment, the cross section of the bypass passage 40a and the cross section of the bypass passage 40b may be the same or different.

Each of <FIG>, <FIG> shows a configuration example of a motion detection device <NUM> according to the seventh embodiment, that does not fall under the scope of the claims. The cylinder device shown in the seventh embodiment is applicable to both a push type cylinder and a pull type cylinder. In the fifth embodiment, the first valve chamber <NUM> is used as a passage of the compressed air. However, in the present embodiment, the compressed air does not go through a space <NUM> (corresponding to the first valve chamber of the previous embodiments) provided between the bottom 10b of the lower wall 1b and the undersurface 5d of the lower rod 5c. In this embodiment, two systems of a first valve rod passage <NUM> and a second valve rod passage <NUM> are provided in the valve rod <NUM>, one of which is on the compressed air supply side and the other is on the discharge side.

<FIG> is an exploded view in which the lower wall 1b of the housing <NUM> is exploded from the upper wall 1a and the barrel wall 1c for ease of explanation. When the lower wall 1b is connected to the upper wall 1a and the barrel wall 1c, a housing passage 22a is connected to a housing passage 22b. A second valve chamber <NUM> is formed from the piston portion 5b and the rod body 5a constituting the output member <NUM>. The second valve chamber <NUM> can be divided into a first region <NUM>, a second region <NUM>, and a third region <NUM> in order from bottom to top depending on the inner diameter. The diameter of the second region <NUM> is large, and the diameters of the first region <NUM> and the third region <NUM> are small.

A first valve rod passage <NUM> and a second valve rod passage <NUM> that open toward the second valve chamber <NUM> are provided coaxially on the valve rod <NUM> protruding from the lower wall 1b. The first valve rod passage <NUM> opens toward a bottom surface 623b of the second valve chamber <NUM>, and the second valve rod passage <NUM> opens toward an inner peripheral wall 623a of the second valve chamber <NUM>. The valve rod <NUM> has a double structure that the outer rod <NUM> inserts the inner rod <NUM>, and a gap between the outer rod <NUM> and the inner rod <NUM> forms the second valve rod passage <NUM>. A leading edge of the inner rod <NUM> is out of surrounding of the outer rod <NUM> and exposed in an enormous shape to form a head end 51a of the valve rod <NUM>.

Apair of seal sections (O-rings) <NUM>, <NUM> are provided around the head end 51a of the valve rod <NUM> so as to have different heights, respectively. Between the seal section <NUM> and the seal section <NUM>, a bypass passage 40c penetrating from the first valve rod passage <NUM> toward the inner peripheral wall 623a of the second valve chamber is provided. A seal section <NUM> provided around the inlet of the second valve chamber <NUM> contacts on an outer peripheral wall <NUM> e of the outer rod <NUM> to seal the second valve chamber <NUM> from the space <NUM>.

<FIG> shows a movement when the valve rod <NUM> and the second valve chamber <NUM> relatively move along the axis C. In an up-advance state of the output member <NUM> shown in <FIG>, the seal section <NUM> is located at a position corresponding to the first region <NUM>, and the second valve rod passage <NUM> is prevented from communication with the second valve chamber <NUM> and the first valve rod passage <NUM> when the seal section <NUM> is blocked. In the state of the output member <NUM> in the middle of descending, which is shown in <FIG>, when the seal section <NUM> and the seal section <NUM> reach the second region <NUM>, the second valve rod passage <NUM> leads to the valve chamber <NUM> side without being blocked by the seal sections <NUM>, <NUM>. Since the first valve rod passage <NUM> is open to the second valve chamber <NUM>, the first valve rod passage <NUM> and the second valve rod passage <NUM> are in communication.

In the state of the descending and retreating output member <NUM> shown in <FIG>, the seal section <NUM> reaches the third region <NUM>. In the third region <NUM>, the second valve rod passage <NUM> is prevented from leading to the second valve chamber <NUM> by blocking the seal section <NUM>. On the other hand, since the bypass passage 40c is located between the seal sections <NUM>, <NUM> and not closed by the seal section <NUM>, the first valve rod passage <NUM> and the second valve rod passage <NUM> are communicated by the bypass passage 40c in a state where the passage is throttled. The throttle of the bypass passage 40c causes a predetermined pressure loss. In this way, the close state is created in the first region <NUM>, the communicating state is created in the second region <NUM>, and the throttled state is created in the third area <NUM>, and this pressure change can be distinguished by a detection valve of a pressure sensor (not shown).

In the present embodiment, when the bypass passage is not provided, the compressed air passage is blocked in the above-mentioned up-advance state or down-retreat state, and is opened halfway. In this case, the seal sections <NUM>, <NUM> are not one pair, and only one of the seal sections <NUM>, <NUM> may be provided.

<FIG> shows a configuration example of a motion detection device <NUM> according to the eighth embodiment.

In this embodiment, when an outer diameter of a valve rod 710c side is changed in two steps from the bottom and a first region <NUM> and a second region <NUM> are respectively set, the outer diameter of the first region <NUM> is the smallest, and the second region <NUM> has the largest outer diameter. A seal section <NUM> is provided on an inner peripheral wall 723a near an outlet on a second valve chamber <NUM> side. The seal section <NUM> has a double structure including an elastic body and a spacer having a small friction coefficient.

In an extended state shown in <FIG>, a space between a first valve chamber <NUM> and the second valve chamber <NUM> is closed by the second region <NUM> and the seal section <NUM>. As shown in <FIG>, when the lower rod 5c descends and the seal section <NUM> reaches the first region <NUM>, a gap is generated between the second valve chamber <NUM> and the valve rod 710c. There is a gap between the second region <NUM> of the valve rod 710c and the second valve chamber <NUM>, and the first valve chamber <NUM> and the second valve chamber are in communication.

Each embodiment and each modification can be further changed as follows. In the above embodiments, one end sides of the compressed air flow passages formed between the first valve chambers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and the valve rod passages 10d, 110d, 210d, 310d, 410d, 510d side are on the first valve chamber <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> sides, respectively, or vice versa. In the seventh embodiment, one of the first valve rod passage <NUM> and the second valve rod passage <NUM> may be set to one end of the compressed air flow passage, and the other may be set to the other end side. In the seventh embodiment, the first valve rod passage <NUM> and the second valve rod passage <NUM> are provided coaxially, but need not be coaxial. For example, the first valve rod passage <NUM> and the second valve rod passage <NUM> may be long holes formed in the inside of the valve rod <NUM> in the longitudinal direction, and these long holes may not be parallel.

In the above embodiments, the output member <NUM> may be turned in the counterclockwise direction in plane view instead of turning in the clockwise direction in plane view in driving the clamp. Further, it is needless to say that the turning angle of the output member <NUM> can be set to a desired angle such as <NUM> degrees. Although the output member <NUM> has the piston portion 5b integrally, as disclosed in the patent literature <NUM>, the piston portion 5b may be provided separately and may be configured to move up and down so as not to follow the turning movement of the output member <NUM>.

Further, the guide groove <NUM> is constituted by the illustrated spiral rotary groove <NUM> and the straight rectilinear groove <NUM>, but the rectilinear groove <NUM> may be omitted. Further, although the double-acting type for supplying the pressurized fluid to the unclamp chamber and the clamp chamber is shown, a single-acting type may be used instead. In addition, although the output member is driven by the pressure fluid, it may be an electric actuator. In addition, it goes without saying that various changes can be made within a range that can be assumed by those skilled in the art.

Claim 1:
A cylinder having an output member (<NUM>) accommodated in a cylinder hole (<NUM>) provided in a housing (<NUM>) and moved up and down by a pressure fluid, comprising:
a first valve chamber (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) provided between a lower wall (1b) of the housing (<NUM>) and the output member (<NUM>);
a second valve chamber (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) being hollowed out of the output member (<NUM>) so as to be provided open toward the first valve chamber (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>);
a valve rod (10c, 110c, 210c, 310c, 410c, 710c) protruding from the lower wall (1b) to be inserted into the second valve chamber (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>),
said valve rod (10c, 110c, 210c, 310c, 410c, 710c) comprising:
a valve rod passage (10d, 110d, 210d, 310d, 410d) provided open toward the second valve chamber (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>); and
a seal section (<NUM>, <NUM>, <NUM>, <NUM>,<NUM>, <NUM>) provided on an outer peripheral wall side of the valve rod (10c, 110c, 210c, 310c, 410c, 710c) or an inner peripheral wall side (10e, 110e, 210e, 310e, 410e) of the second valve chamber (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) between the valve rod (10c, 110c, 210c, 310c, 410c, 710c) and the second valve chamber (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>),
characterized in that
a compressed air flow passage formed between the first valve chamber (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and the second valve chamber (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) is configured so as to have a close region sealed by the seal section (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and an open region released from sealing when the valve rod (10c, 110c, 210c, 310c, 410c, 710c) and the second valve chamber (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) move relative to each other,
wherein compressed air is supplied from one end of the compressed air flow passage, and the other end of the compressed air flow passage is open to an outside air.