Electromagnetic valve equipped with manual operation element including safety device

On an outer surface of an electromagnetic valve body, a manual operation element is provided slidably horizontally, and a slide member is provided slidably in a direction orthogonal to a sliding direction of the manual operation element. The slide member is movable to a lock position and a non-lock position. At the lock position, the slide member is retained by the manual operation element to lock the manual operation element at a non-switch position. At the non-lock position, the slide member unlocks the manual operation element to allow the manual operation element to move toward a switch position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electromagnetic valve including a manual operation element that is manually operated to switch a valve member, and a safety device that prevents erroneous operation of the manual operation element.

2. Description of the Related Art

While a typical electromagnetic valve is configured to switch a valve member for switching a flow passage of fluid by the action of electromagnetic force, it includes a manual operation mechanism that allows the valve member to be manually switched during a blackout, in an emergency, or during maintenance. There are push-in type and slide type manual operation mechanisms. In a push-in type, a switch shaft provided in an electromagnetic valve is pushed in by pressing an operating member provided on an outer surface of the electromagnetic valve, thereby switching a valve member. In contrast, in a slide type, a switch shaft is pushed in by an inclined face or the like provided on a lower face of an operating member, which is provided on an outer surface of an electromagnetic valve, by horizontally sliding the operating member along the outer surface, thereby switching the valve member, as disclosed in Patent Literature, Japanese Unexamined Patent Application Publication No. 11-22850. The slide type is easier to handle than the push-in type.

The electromagnetic valve is normally equipped with a safety device that prevents erroneous operation of the operating member. Patent Literature, Japanese Unexamined Patent Application Publication No. 11-22850, discloses a safety device that prevents erroneous operation of an operating member (operating piece) of the slide type. The safety device includes a cover covering the operating piece, and the cover is connected to an electromagnetic valve such as to be turnable about a shaft. When the operating piece is covered with the cover, it cannot be moved. The operating piece can be moved after the cover is opened.

BRIEF SUMMARY OF THE INVENTION

However, in the safety device disclosed in Patent Literature 1, one end of the cover is connected to the electromagnetic valve by the shaft, and the operating piece is covered and exposed to the outside by turning the cover about the shaft. Hence, a wide operation space is needed to turn the cover, and the operation of turning the cover is troublesome. Moreover, when the operating piece is located at an operating position, for example, the cover takes a semi-open or a semi-closed posture obliquely standing in contact with the operating piece. Therefore, the operating piece is visible or not visible according to the angle, and it is difficult to check the operating state of the operating piece.

An object of the present invention is to mount a cover for preventing erroneous operation of a slide type manual operation element included in an electromagnetic valve so that the cover can be operated even in a condition where a wide operation space is not provided, to enhance operability of the cover, and to easily check operating states of the cover and the manual operation element.

To achieve the above object, the present invention provides an electromagnetic valve in which an electromagnetic valve body including a main valve section incorporating a valve member configured to switch a flow passage of fluid, an electromagnetic operating section configured to switch the valve member by an electromagnetic force, and a manual operating section to be manually operated to switch the valve member is provided with a safety device configured to prevent erroneous operation of a manual operation element provided in the manual operating section.

The manual operation element is provided in the electromagnetic valve body to be horizontally slidable, and is movable to a non-switch position and a switch position. The safety device includes a base member fixed to the electromagnetic valve body, and a slide member held on the base member to be slidable in a direction orthogonal to a sliding direction of the manual operation element. The slide member is movable to a lock position and a non-lock position. The slide member is in contact with the manual operation element at the lock position to lock the manual operation element at the non-switch position, and the slide member is separate from the manual operation element at the non-lock position to allow the manual operation element to move toward the switch position.

In the present invention, preferably, the slide member includes a horizontal slide frame extending in the same direction as the sliding direction of the manual operation element, and a vertical slide frame continuing from the horizontal slide frame at a right angle. The horizontal slide frame has a lock face. The lock face is in contact with the manual operation element when the slide member is located at the lock position, and the lock face is separate from the manual operation element when the slide member is located at the non-lock position.

In this case, preferably, when the slide member is located at the non-lock position and the manual operation element is located at the switch position, the slide member is unable to move toward the lock position while a part of the manual operation element is placed under the horizontal slide frame, and, when the manual operation element is located at the non-switch position, the slide member is movable between the non-lock position and the lock position while the manual operation element is completely withdrawn from under the horizontal slide frame.

In the present invention, the base member includes a fitting groove in which the slide member is slidably fitted, and the fitting groove includes a horizontal groove portion in which the horizontal slide frame is fitted, and a vertical groove portion in which the vertical slide frame is fitted.

In the present invention, preferably, a positioning hole and a positioning projection to be fitted in the positioning hole are provided in one and the other of the base member and the slide member, respectively, and, when the slide member is moved from the lock position to the non-lock position, the positioning projection is caught in the positioning hole to position the slide member at the non-lock position.

Similarly, an elastic projection and an engaging portion that elastically engage with each other when the slide member is located at the lock position and the non-lock position can be provided in one and the other of the slide member and the base member, respectively.

Preferably, the positioning hole and the positioning projection, and the elastic projection and the engaging portion are provided in one and the other of a groove side wall of the vertical groove portion in the base member and a side face of the vertical slide frame in the slide member, respectively.

In the present invention, at least one of the slide member and the base member can have an identification mark that is visible from outside when the slide member is located at any one of the lock position and the non-lock position.

Preferably, the identification mark is formed by coloring a part of the slide member, is covered with the base member when the slide member is located at the lock position, and is exposed from the base member when the slide member is moved to the non-lock position.

According to the present invention, since the manual operation element can be locked at the non-switch position and unlocked to be moved to the switch position by sliding the slide member to the lock position and the non-lock position, the slide member does not need to be widely turned, unlike the related art. Therefore, a wide operation space where the slide member is turned is unnecessary, and the operation of the slide member is easier than the turning operation. Further, since the slide member is slid in the direction orthogonal to the sliding direction of the manual operation element, a positional relationship in the height direction of the slide member and the manual operation element relative to the outer surface of the electromagnetic valve is clearly different between the lock position and the non-lock position. Thus, the operating position of the slide member can be easily checked, and the operating position of the manual operation element can also be checked easily.

DETAILED DESCRIPTION OF THE INVENTION

Drawings illustrate an embodiment of an electromagnetic valve equipped with a manual operation element including a safety device according to the present invention. As illustrated inFIGS. 1,4, and5, in the electromagnetic valve, an electromagnetic valve body10is provided with a safety device50that prevents erroneous operation of manual operation elements31A and31B.

The electromagnetic valve body10includes a main valve section11incorporating a valve member16for switching a flow passage in which main fluid, such as air, flows, an electromagnetic operating section12that switches the valve member16by the action of electromagnetic force, and a manual operating section13to be manually operated to switch the valve member16. The manual operating section13includes the above-described manual operation elements31A and31B. The main valve section11, the manual operating section13, and the electromagnetic operating section12are connected in line in a direction of a center axis L of the valve member16.

The main valve section11of the electromagnetic valve body10includes a main valve section housing18shaped like a rectangular block. The valve member16of a spool type is incorporated in a valve hole19provided in the main valve section housing18in a manner such as to be slidable in the direction of the center axis L. At opposite ends of the valve member16, pilot pistons20aand20bare provided integrally with or separately from the valve member16, and pressurizing chambers21aand21bare provided to apply the pilot fluid pressure to the pilot pistons20aand20b.By moving the valve member16in a right-left direction ofFIG. 1through the operation of the pilot pistons20aand20b,flow passages connecting a plurality of ports P, A, B, EA, and EB provided in the main valve section housing18are switched. However, since such a structure of the main valve section11is well known and does not directly relate to the scope of the invention, a further detailed description of the structure is skipped.

The electromagnetic operating section12includes two electromagnetically operated pilot valves25aand25b.By alternately turning on and off the pilot valves25aand25b,pilot fluid from the port P is alternately supplied to and discharged from the pressurizing chambers21aand21bso that the pilot pistons20aand20bare alternately operated to switch the valve member16.

For example, when the upper first pilot valve25ais turned on and the lower second pilot valve25bis turned off, pilot fluid is supplied to the first pressurizing chamber21aon a left side of the valve member16, and the second pressurizing chamber21bon a right side is opened to the outside. Hence, the valve member16is driven to the right inFIG. 1by the first pilot piston20a.

Conversely, when the upper first pilot valve25ais turned off and the lower second pilot valve25bis turned on, pilot fluid is supplied to the second pressurizing chamber21bon the right side of the valve member16, and the first pressurizing chamber21aon the left side is opened to the outside. Hence, the valve member16is driven to the left by the second cam portion20b,and is brought into a switch state ofFIG. 1.

The two pilot valves25aand25bhave the same structure, are formed as three-port electromagnetic valves, and are attached to an electromagnetic section housing26.

The electromagnetic section housing26is shaped like a quadratic prism extending long vertically, and the vertical length thereof is more than the vertical length of the main valve section housing18. An upper end of the electromagnetic section housing26is nearly aligned with an upper end of the main valve section housing18, but a lower end thereof protrudes downward from a lower end of the main valve section housing18.

The electromagnetic section housing26has an inner end surface26afacing toward the main valve section11, and an outer end surface26bfacing an opposite side. The two pilot valves25aand25bare attached to the outer end surface26bwhile they are vertically aligned with their respective longitudinal ends butting against each other. A mount portion26chorizontally extends from a middle portion of the inner end surface26atoward the main valve section11. A manual operating section housing30of the manual operating section13is mounted on the mount portion26c,and the main valve section housing18is connected to the manual operating section housing30.

A lateral width (thickness) of the electromagnetic section housing26is substantially equal to lateral widths of the manual operating section housing30and the main valve section housing18, while a lateral width of the pilot valves25aand25bis slightly smaller than the lateral width of the electromagnetic section housing26.

As illustrated inFIGS. 1 to 5, the manual operating section13includes the above-described two manual operation elements31A and31B, and two switch shafts32corresponding to the manual operation elements31A and31B. Upper ends of the switch shafts32are in contact with lower surfaces of the manual operation elements31A and31B. By pressing any of the switch shafts32through the corresponding manual operation element31A or31B, a communication state of the flow passages for pilot fluid is switched, whereby the pilot fluid is directly supplied to the pressurizing chamber21aor21b,and the valve member16is switched to the right or the left.

The structure and operation of the manual operating section13are substantially the same as those adopted in a well known electromagnetic valve except that the manual operation elements31A and31B are of a slide type. Hence, structures and operations relating to the manual operation elements31A and31B and the switch shafts32will be mainly described in detail below, and descriptions of other structures and operations are skipped.

The two manual operation elements31A and31B are members shaped like a rectangle that extends long in the direction of the center axis L in plan view, and have the same structure. The manual operation elements31A and31B are arranged parallel to one side and the other side in a width direction of an outer surface, that is, an upper surface of the manual section housing30, and are able to slide horizontally (in a direction parallel to the center axis L) along the upper surface. For this reason, as illustrated inFIGS. 9 and 10, the upper surface of the manual section housing30has two parallel operation grooves33, and the manual operation elements31A and31B are slidably received in the operation grooves33. Guide rails34facing inward at upper ends of groove walls of the operation grooves33are fitted in guide grooves35provided on side surfaces of the manual operation elements31A and31B. This structure allows the manual operation elements31A and31B to be slid without falling upward off the operation grooves33.

Each of the manual operation elements31A and31B has a first end31aclose to the main valve section11and a second end31bclose to the electromagnetic operating section12. From a position on an upper surface thereof near the first end31a,a finger hook portion36projects upward for sliding operation.

As illustrated inFIGS. 3 and 10, a lower surface of each of the manual operation elements31A and31B has a groove-shaped recess37extending to a middle portion between the second end31band the first end31a.A ceiling wall of the recess37has a first operation face38, a second operation face39, and an inclined face40that allow the switch shaft32to move up and down.

The first operation face38is provided at a position closer to the second end31bthan the second operation face39, and a distance from the first operation face38to the upper surface of the manual section housing30is longer than a distance from the second operation face39to the upper surface of the manual section housing30. The inclined face40is provided between the first operation face38and the second operation face39such as to gradually slope in a direction to become closer to the upper surface of the manual section housing30as it extends from the first operation face38toward the second operation face39.

Each of the manual operation elements31A and31B can be placed at a non-switch position X shifted toward the main valve section11(FIG. 3) and a switch position Y shifted toward the electromagnetic operating section12(FIG. 10) by sliding operation. As illustrated inFIG. 3, the non-switch position X is a position where the first operation face38opposes the upper end of the switch shaft32, but does not push the switch shaft32. When the manual operation element31A or31B is slid from the non-switch position X to the switch position Y, the switch shaft32is gradually pushed down by the inclined face40. When the manual operation element31A or31B reaches the switch position Y, the upper end of the switch shaft32is brought into contact with the second operation face39, as illustrated inFIG. 10, and the switch shaft32is completely pushed down, so that the pilot flow passage is switched and the valve member16is switched.

When the manual operation element31A or31B is returned from the switch position Y to the non-switch position X, the switch shaft32is raised and returned to the position ofFIG. 3.

The switch shaft32is received slidably in the up-down direction in a shaft hole41that extends in the manual section housing30in a direction orthogonal to the center axis L, and an upper end thereof protrudes from the upper surface of the manual section housing30. The switch shaft32is constantly biased upward by a return spring42.

The first manual operation element31A, of the two manual operation elements31A and31B, and the switch shaft (not illustrated) to be operated by the first manual operation element31A correspond to the first pilot valve25a. The second manual operation element31B and the switch shaft32to be operated by the second manual operation element31B correspond to the second pilot valve25b.Therefore, when the manual operation element31A is moved to the switch position Y, pilot fluid from the port P is supplied into the first pressurizing chamber21a,and the valve member16is moved to the right inFIG. 1. When the second manual operation element31B is moved to the switch position Y, as illustrated inFIG. 10, the pilot fluid is supplied into the second pressurizing chamber21b,and the valve member16is moved to the left inFIG. 1.

Reference numeral43inFIG. 1denotes a hollow power receiving connector protruding downward from the lower surface of the manual section housing30, and pin-shaped terminals having continuity to the pilot valves25aand25bare incorporated in the power receiving connector43. By connecting a power feeding connector of a control device to the power receiving connector43, power is fed to the pilot valves25aand25b.

As illustrated inFIGS. 4 and 5and other figures, the safety device50includes a base member51and a slide member52. The base member51is fixed to the electromagnetic valve body10, and the slide member52is held on the base member51such as to be slidable in a direction (up-down direction in the figures) orthogonal to a sliding direction of the manual operation elements31A and31B.

The base member51is formed of a rigid nonmagnetic material such as synthetic resin or an aluminum alloy, and is angularly U-shaped in side view. The base member51includes a vertical base frame51ashaped like a narrow plate that vertically extends to cover the entire end faces of the two pilot valves25aand25b,an upper horizontal base frame51bshaped like a narrow plate that horizontally extends from an upper end of the vertical base frame51ato cover an upper side face of the upper pilot valve25a,and a lower horizontal base frame51cshaped like a narrow plate that horizontally extends from a lower end of the vertical base frame51ato cover a lower side face of the lower pilot valve25b. The base member51is fixed to the end face of the pilot valve25aand the upper surface of the electromagnetic section housing26at the vertical base frame51aand the upper horizontal base frame51bby fixing screws53.

Reference numeral54ain the figures denotes a positioning pin provided on a back surface of the vertical base frame51a.The positioning pin54ais fitted in a positioning hole54bto position the base member51when the base member51is fixed to the electromagnetic valve body10.

On an outer surface of an upper half of the base member51, an L-shaped fitting groove55, in which the slide member52is fitted movably in the up-down direction, extends from an upper half of the vertical base frame51ato the upper horizontal base frame51b.The fitting groove55is provided between right and left groove side walls56projecting outward from both side ends in the width direction of the vertical base frame51aand the upper horizontal base frame51b,and is formed by a vertical groove portion55aextending along the vertical base frame51a,and a horizontal groove portion55bextending along the upper horizontal base frame51b.

On inner side faces of the right and left groove side walls56of the vertical groove portion55a,guide grooves56a,in which ribs58on side faces of the slide member52are slidably fitted, extend long in the up-down direction. A rectangular engaging projection57standing upward from the upper horizontal base frame51bis provided at a distal end of the horizontal groove portion55b.The engaging projection57has a cavity inside.

As shown by chain lines inFIG. 5, the base member51may include right and left side base frames51dthat cover the entire right and left side faces of the two upper and lower pilot valves25aand25b.When the base member includes the side base frames51d,the shape of the base member is similar to the shape of a slip case that protects a book inserted therein.

The slide member52is L-shaped and is formed of a rigid nonmagnetic material such as synthetic resin or an aluminum alloy, and includes a vertical slide frame52aextending in the up-down direction and a horizontal slide frame52bcontinuing from an upper end of the vertical slide frame52aat a right angle. The horizontal slide frame52bextends in the same direction as the sliding direction of the manual operation elements31A and31B.

On right and left side faces of the vertical slide frame52a,the above-described ribs58to be fitted in the guide grooves56aof the base member51extend in the up-down direction. Upward and downward movements of the slide member52are guided by the guide grooves56aand the ribs58.

A lock face52cat a distal end of the horizontal slide frame52bfaces toward the first ends31aof the manual operation elements31A and31B, and a rectangular engaging hole59in which the engaging projection57of the base member51is to be fitted is provided in a position of the horizontal slide frame52bnear the lock face52c.As illustrated inFIG. 3, when the slide member52is located at a down position (a lock position M), the engaging projection57is fitted and caught in the engaging hole59, so that the slide member52is restricted from moving in a horizontal direction (direction along the center axis L).

Antislip members60are provided at a position of the horizontal slide frame52band a position of the vertical slide frame52aon an outer surface of the slide member52to prevent the finger from slipping when sliding the slide member52. The antislip members60are formed by a plurality of parallel ribs.

At a position on a lower surface of the horizontal slide frame52bslightly shifted rearward from the lock face52c,a stopper61extends in the width direction of the horizontal slide frame52b.As illustrated inFIG. 10, when any of the manual operation elements31A and31B is moved to the switch position Y, the second end31bof the manual operation element31A or31B is brought into contact with the stopper61, so that the manual operation element31A or31B stops at the switch position Y. Alternatively, the manual operation element31A or31B may be stopped at the switch position Y by contact with the corresponding switch shaft32.

The slide member52is movable to two positions, that is, a lock position M and a non-lock position N.

As illustrated inFIGS. 1 to 3, the lock position M is an operating position taken when the slide member52is moved down to move the horizontal slide frame52bcloser to the upper surface of the electromagnetic valve body10. At the lock position M, a lower face of the rib-shaped stopper61provided on the lower surface of the horizontal slide frame52bis in contact with the upper surface of the upper horizontal base frame51bof the base member51, whereby the slide member52is stopped and positioned at the lock position M. At the lock position M, the lock face52cof the horizontal slide frame52bis located at the same height as that of the manual operation elements31A and31B from the upper surface of the electromagnetic valve body10, and contacts with the second ends31bof the manual operation elements31A and31B to lock the manual operation elements31A and31B at the non-switch position X. For this reason, none of the two manual operation elements31A and31B can be moved toward the switch position Y.

As illustrated inFIGS. 6 to 10, the non-lock position N is an operating position taken when the slide member52is moved up to move the horizontal slide frame52baway from the upper surface of the electromagnetic valve body10. At the non-lock position N, a distal end portion52dof the horizontal slide frame52bfrom the lock face52cto the stopper61is located at a position higher than the manual operation elements31A and31B and is thereby out of contact with the manual operation elements31A and31B. Hence, the manual operation elements31A and31B are unlocked, and the two manual operation elements31A and31B are allowed to move toward the switch position Y.FIGS. 6 to 10illustrate a state in which the second manual operation element31B is slid to the switch position Y and the first manual operation element31A is held at the non-switch position X without being slid.

When the manual operation element31B is moved to the switch position Y, as illustrated inFIG. 10, a second end31bside of the manual operation element31B enters under the distal end portion52dof the horizontal slide frame52b,stops at a position in contact with the stopper61, and overlaps with the horizontal slide frame52b.At this time, a first end31aside of the manual operation element31B having the finger hook portion36remains exposed outside the horizontal slide frame52b.Since the exposed first end31aside is visible from any angle, it can be reliably determined that the manual operation element31B is located at the switch position Y.

While a length of the portion of the manual operation element31B entering under the horizontal slide frame52bat the switch position Y is preferably about 40 to 50%, it may be other lengths as long as the portion is visible from outside.

When at least one of the two manual operation elements31A and31B is thus located at the switch position Y, the distal end portion52dof the horizontal slide frame52bof the slide member52at the non-lock position N is located on the manual operation element31A or31B at the switch position Y. Hence, if the slide member52is pushed down, it contacts with the upper surface of the manual operation element31A or31B, but cannot be pushed down to the lock position M. For this reason, erroneous operation of the slide member52can be prevented reliably.

The base member51and the slide member52are provided with a positioning mechanism for stopping and positioning the slide member52at the non-lock position N and an elastic retaining mechanism for retaining the slide member52at the lock position M and the non-lock position N.

The positioning mechanism is constituted by a positioning hole62provided in the base member51and a positioning projection63provided on the slide member52. That is, as illustratedFIGS. 4,5,11, and12, the positioning hole62extending in the up-down direction is provided in any one of the right and left groove side walls56of the vertical groove portion55ain the base member51, and the positioning projection63to be fitted in the positioning hole62is provided on one side face of the vertical slide frame52ain the slide member52.

To form the positioning projection63, an arm64extending in the up-down direction is provided in a part of a side surface of a frame-shaped portion52eprovided on a back side of the vertical slide frame52a.The arm64is connected at an upper end to the frame-shaped portion52e,and is separate at side faces and a lower end from the frame-shaped portion52e.The positioning projection63is provided at the lower end of the arm64having elasticity in a position such as to project sideward from the vertical slide frame52a.An upper end face of the positioning projection63is horizontally flat, and a lower end face of the positioning projection63is an inclined face that gradually slopes in a direction to become closer to the upper end face as it extends toward a projection end of the positioning projection63.

When the slide member52is at the lock position M, the positioning projection63is located at the center of the positioning hole62, as illustrated inFIGS. 1 and 11. When the slide member52moves upward from the lock position M to the non-lock position N, the upper end face of the positioning projection63is brought into contact with and retained by an upper edge of the positioning hole62, as illustrated inFIGS. 6 and 12, so that the slide member52is stopped at the non-lock position N and positioned at that position.

As illustrated inFIGS. 4,5,11, and12, the elastic retaining mechanism is constituted by an engaging portion70provided in the groove side wall56of the vertical groove portion55ain the base member51, and elastic projections71provided on the side face of the vertical slide frame52ain the slide member52.

The engaging portion70includes two engaging holes72and two engaging recesses73. The two engaging holes72and the two engaging recesses73are alternately arranged in the up-down direction in the groove side wall56having the positioning hole62and below the positioning hole62. The engaging holes72penetrate through the groove side wall56. The engaging recesses73are provided in an inner surface of a wall portion dividing the upper engaging hole72and the positioning hole62and an inner surface of a wall portion dividing the upper and lower engaging holes72in a manner such as not to penetrate through the groove side wall56.

Two elastic projections71are provided in a part of the frame-shaped portion52eon the back side of the vertical slide frame52ain the slide member52. That is, two elastic pieces74extending in the up-down direction are formed at a position below the position of the frame-shaped portion52ewhere the positioning projection63is provided, by thinning a part of the frame-shaped portion52eand separating a side face portion, excluding upper and lower ends, from the frame-shaped portion52e.In the centers of the elastic pieces74, the elastic projections71are curved to project sideward. The center distance between the two elastic projections71is equal to the center distance between the two engaging holes72and the center distance between the two engaging recesses73.

With this structure, when the slide member52is located at the lock position M, the two elastic projections71are engaged with the two engaging holes72to hold the slide member52at the lock position M, as illustrated inFIG. 11.

When the slide member52is moved upward from the lock position M to the non-lock position N inFIG. 11, the two elastic projections71are elastically disengaged from the engaging holes72by elastic deformation of the elastic pieces74, and move to the engaging recesses73beyond edges of the engaging recesses73. When the slide member52is completely moved to the non-lock position N, the elastic projections71are fitted in the engaging recesses73to hold the slide member52at the non-lock position N, as illustrated inFIG. 12.

When the slide member52is moved downward from the non-lock position N ofFIG. 12to the lock position M ofFIG. 11, the two elastic projections71are elastically disengaged from the engaging recesses73beyond the edges by elastic deformation of the elastic pieces74. When the slide member52is completely moved to the lock position M, the elastic projections71are fitted in the engaging holes72to hold the slide member52at the lock position M, as illustrated inFIG. 11.

In this way, the slide member52is reliably held at the lock position M and the non-lock position N by the elastic retaining mechanism. When the slide member52is slid between the lock position M and the non-lock position N, the elastic projections71are elastically fitted in and disengaged from the engaging holes72and the engaging recesses73, and the feeling of fitting and disengagement is transmitted to the hand. Hence, it is possible to reliably sense that the slide member52is moved to the lock position M and the non-lock position N.

Further, since the manual operation elements31A and31B can be locked and unlocked only by sliding the slide member52to the lock position M and the non-lock position N, erroneous operation of the manual operation elements31A and31B can be reliably prevented by a simple action. Moreover, since the slide member52does not need to be turned, unlike the cover in the safety device of the related art, a wide space for turning the slide member52is unnecessary.

When the slide member52is located at the lock position M, the upper surface of the horizontal slide frame52bis substantially at the same height as the upper surfaces of the manual operation elements31A and31B, and there is no height difference between the slide member52and the manual operation elements31A and31B. When the slide member52is moved to the non-lock position N, the horizontal slide frame52bis placed at a position higher than the manual operation elements31A and31B, and a height difference is formed between the slide member52and the manual operation elements31A and31B. In this way, the positional relationship of the slide member52and the manual operation elements31A and31B relative to the outer surface of the electromagnetic valve is clearly different between the lock position M and the non-lock position N. Hence, the operating position of the slide member52can be easily and reliably checked from outside. Further, since the manual operation elements31A and31B are not entirely covered with the slide member52, regardless of where the slide member52and the manual operation elements31A and31B are located, the positions of the manual operation elements31A and31B can be checked easily.

To even more easily and clearly determine whether the slide member52is located at the lock position M or the non-lock position N, any one of the slide member52and the base member51can have identification marks65that are visible from outside only when the slide member52is moved to any one of the lock position M and the non-lock position N. In the illustrated embodiment, as illustrated inFIGS. 4 and 5, the identification marks65are formed by putting linear marks of a striking color different from the color of the slide member52, such as orange or red, on right and left side faces of the horizontal slide frame52band on the lock face52cat the distal end of the horizontal slide frame52b.When the slide member52is moved down and located at the lock position M, as illustrated inFIG. 1, the identification marks65are not visible from outside because they are completely covered with the base member51. In contrast, when the slide member52is moved up to the non-lock position N, as illustrated inFIG. 6, the identification marks65are exposed from the base member51and become visible from outside, so that it can be determined that the slide member52is located at the non-lock position N.

The identification marks65can be formed by a straight line, a curved line, a dot, a sign, or a pattern, or alternatively, can he formed by giving the above-described striking color to the entirety or a part of the right and left side faces of the horizontal slide frame52band/or the entirety or a part of the lock face52c.

Instead of being formed on the slide member52or while being formed on the slide member52, the identification marks65can be formed on the base member51. When the identification marks65are formed on the base member51, for example, they can be formed in portions of the vertical base frame51aof the base member51that are covered with the slide member52and are exposed outside when the slide member52is moved up and down to the lock position M and the non-lock position N.

While the arm64and the positioning projection63are provided on the vertical slide frame52aof the slide member52and the positioning holes62are provided in the groove side wall56of the vertical groove portion55aof the base member51in the positioning mechanism of the embodiment, conversely, the arm64and the positioning projection63can be formed in the groove side wall56of the vertical groove portion55aof the base member51and the positioning hole62can be formed in the vertical slide frame52aof the slide member52.

The arrangement of the elastic projections71and the engaging portion70in the elastic retaining mechanism in the embodiment may be reversed such that the elastic projections71are formed on the groove side wall56of the vertical groove portion55aof the base member51and the engaging portion70is formed on the vertical slide frame52aof the slide member52.

Further, the elastic retaining mechanism can be constituted by one elastic projection71, and two engaging holes72or two engaging recesses73such that the elastic projection71engages with one of the engaging holes72or engaging recesses73when the slide member52is located at the lock position M and such that the elastic projection71engages with the other engaging hole72or engaging recess73when the slide member52is located at the non-lock position N.

Conversely, the elastic retaining mechanism can be constituted by two elastic projections71, and one engaging hole72or one engaging recess73such that one of the elastic projections71engages with the engaging hole72or the engaging recess73when the slide member52is located at the lock position M and such that the other elastic projection71engages with the engaging hole72or the engaging recess73when the slide member52is located at the non-lock position N.

Further, the elastic retaining mechanism may he provided not only one of the right and left sides of the base member51and the slide member52, but also on both the right and left sides.

While the illustrated embodiment provides the double-pilot electromagnetic valve including the two pilot valves25aand25band the two manual operation elements31A and31B, the present invention is also applicable to a single-pilot electromagnetic valve including one pilot valve and one manual operation element.

In the single-pilot electromagnetic valve, the vertical length of the electromagnetic section housing26of the electromagnetic valve body10and the vertical length of the base member51of the safety device50are normally set in accordance with the size of one pilot valve. The single-pilot electromagnetic valve can be formed by utilizing the electromagnetic section housing26of the electromagnetic valve body10and the base member51in the double-pilot type and removing any one of the pilot valves, that is, the pilot valve25band any one of the manual operation elements, that is, the manual operation element31B while leaving the other pilot valve25aand the other manual operation element31A. In this case, a dummy member having a shape and a size similar to those of the removed pilot valve25bcan be attached instead of the pilot valve25b,or a cover member covering the operation groove33in the upper surface of the manual section housing30can be mounted instead of the removed manual operation element31B.

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