Telescopic support arm

Abstract: In a telescopic support arm having a slidable outside arm (1) and inside arm (2), a first slot (3) is formed in the outside arm (1), and an abutting piece (8) is disposed inside the outside arm, while a second slot (7) is formed in the inside arm, and a rotatable stopping piece (4) is disposed inside the inside arm. The stopping piece (4) is rotated as the end portion of the slots (3,7) and the abutting piece (8) are engaged with each other, so as to be projected out of and into the slot (3,7) respectively, and as the stopping piece (4) rotates, the outside arm and inside arm are slidable in the extending direction and contracting direction. The stopping piece (4) is furnished with a buffer mechanism (14), and this buffer mechanism is preferably composed of a holding piece (10) of the stopping piece (4), a spring (13) for pulling this holding piece in the contracting direction of the telescopic support arm, and a further slot (12) for supporting slidably a support shaft (11) of the stopping piece (4). A rack (5) may be disposed along the longitudinal direction of the outside arm, and a locking piece (6) can be disposed in the inside arm, with the tooth part (5a) of the rack (5) and the pawl part (6a) of the locking piece (6) are engaged with each other, so that the telescopic support arm is arrested at a desired position, thereby adjusting the length.

Description: The present invention relates to a telescopic support arm used in windows, inspection ports, doors of various devices and other similar constructions. Various telescopic support arms have been hitherto invented. For example, a support arm is designed in a telescopic structure by moving a piston rod reciprocally within a cylinder. Such a telescopic support arm is used by attaching one end to the door and the other end to the door support frame. In such conventional telescopic support arms, however, when the door is forcefully opened until the telescopic support arm is fully expanded, an impact acts directly on the junction of the cylinder and piston rod, and therefore the durability of the arm is poor. Alternatively when the telescopic support arms are used at both sides, and where the door is attached to the support frame in a distorted state or if a gap is formed in mounting of the door on the support frame, either one or both of the telescopic support arms may not be fully expanded, and the door cannot be opened or closed smoothly. Furthermore, in such a conventional telescopic support arm, the door cannot be stopped at an arbitrary position, but can be stopped only at the fully open position or at a preset position of a specific opening width of the door. Therefore, if it is desired to stop the door at a slightly open position or when frequently varying the opening width of the door, it is very inconvenient with such telescopic support arm. In US-A-2001507 there is disclosed a telescopic support arm which illustrates the disadvantages described above. The precharacterising part of claim 1 is based upon this disclosure. It is an object of the invention to solve the problems of the conventional telescopic support arm. In a first aspect of the invention there is provided a telescopic support arm comprising an outside arm and an inside arm, the inside arm being arranged to slide within the outside arm between a contracted state and an extended state, the inside arm having a stopping piece for releasably securing the outside arm at its extended state, characterised in that the outside arm has a first slot, and an abutting piece and the inside arm has a second slot; in that the stopping piece is rotatable by end portions of the first and second slots and the abutting piece and is disposed such that it engages with the end portion of the slots in the extended state to resist movement of the arms; and in that there is provided a buffer mechanism which slidably supports the stopping piece and which resiliently urges the stopping piece in a contracting direction of the support arm. Preferably, the arm comprises a holding piece of the stopping piece, a spring for pulling the holding piece in the contracting direction of the telescopic support arm, and a further slot for slidably supporting a support shaft of the stopping piece. The buffer mechanism is preferably disposed in the stopping piece, and is advantageously composed of a holding piece of the stopping piece, a spring for pulling the holding piece in the contracting direction of the telescopic support arm, and a slot for slidably supporting a support shaft of the stopping piece. In this invention, moreover, a rack is preferably disposed on the outside arm along the longitudinal direction and a locking piece is provided in the inside arm, so that a tooth part of the rack is engagable with a pawl part of the locking piece. Thus when the telescopic support arm expands, the pawl part engages with each tooth of the tooth pact so that the length of the support arm is adjusted by arresting the pawl part at a desired position. Moreover, holes which align and penetrate through both the outside arm and inside arm may be provided at predetermined positions. The telescopic support arm of the invention, provided with such means as mentioned above, obtains the following actions. In the telescopic support arm having slots, the abutting piece and the stopping piece, the abutting piece and the stopping piece are firstly engaged with each other, and the stopping piece is further engaged with the end portion of the slot in the outside arm so that the support arm may be supported securely at the extended position. Risks such as unexpected closing of a door while working thereunder are avoided. Furthermore, a 180° rotation of the stopping piece causes the once extended telescopic support arm to contract easily. If the door is opened forcefully, on the other hand, the stopping piece, being pulled in the contracting direction by the spring, slides within the range of the length of the slot of the buffer mechanism and therefore direct damage on the abutting piece or the stopping piece is not induced, so that a durable support arm may be provided. In the telescopic support arm in which the rack and the locking piece are provided, when the telescopic support arm expands, the pawl part of the locking piece moves intermittently in small strokes on the tooth part of the rack. In this expanding state, to the contrary, when pushing force in the contracting direction is applied on the support arm, the pawl part of the locking piece engages with a certain tooth of the tooth part of the rack and is arrested there, so that the movement in the contracting direction is stopped. Since the pawl part moves with engaging with each tooth of the tooth part, it is possible to provide a telescopic support arm capable of being set at a desired length. The invention will be described further by way of example with reference to the accompanying drawings in which:- Fig. 1 is a partially cutaway perspective view of a telescopic support arm of the invention; Fig. 2 is a partially cutaway perspective view of an outside arm; Fig. 3 is a partially cutaway perspective view of an inside arm; Fig. 4 is a perspective view showing the position during use of a mounted telescopic support arm of the invention; Fig. 5 is an explanatory diagram showing the position of the tooth part of the rack and pawl part of the locking piece, when extending the telescopic support arm; Fig. 6 is an explanatory diagram showing the position of tooth part of the rack and pawl part of the locking piece, when contracting the telescopic support arm; Fig. 7 is an explanatory diagram showing the position of the stopping piece of the inside arm abutting against the abutting piece of the outside arm (the state just before the stopping piece slightly projects from the slot of the arm); Fig. 8 is an explanatory diagram showing the position of the stopping piece of the inside arm slightly projecting from the slot of the outside arm; Fig. 9 is an explanatory diagram showing the position of the stopping piece of the inside arm stopped in the end portion of the slot of the outside arm; Fig. 10 is an explanatory diagram showing the position of the stopping piece rotated and disengaged from the front end (right) side end portion of the slot of the outside arm and engaged with the rear end (left) side end portion; Fig. 11 is an explanatory diagram showing the position of the stopping piece of the inside arm rotated further to locate into the outside and inside arm, after the state in Fig. 10, when the telescopic support arm is contracted; Fig. 12 is an explanatory diagram showing the position of the telescopic support arm further extended by receiving the buffer action as a force is further added in the extending direction in the state in Fig. 8; Fig. 13 is a perspective view showing the configuration of the stopping piece, abutting piece, and slot of the outside arm in the position in Fig. 10; and Fig. 14 is a perspective view having a penetrating arm penetrating through the outside and inside arms. The constitution of a telescopic support arm relating to the invention is described below while referring to an embodiment in conjunction with the accompanying drawings. As shown in Fig. 1 which is a perspective view of the telescopic support arm of the invention, and outside arm 1 and an inside arm 2 are free to slide relative to one another. As specifically described below, in this diagram, the telescopic support arm is extended, and the stopping piece 4 of the inside arm 2 is stopped in the front end side end portion of the slot 3 in the outside arm 1. In the following description, the right side in each drawing except Fig. 4 is called the front end side, and the left side is called the rear end side. As shown in Fig. 2, the outside arm 1 is formed as a quadrangular tube by joining two metal plates face to face folded in an approximately U-section, and the rack 5 is disposed inside along the longitudinal direction. A first slot 3 is disposed at the rear end side 1b of the outside arm, and an abutting piece 8 is provided inside this rear end side 1b. The inside arm 2 is made of a metal plate folded in an approximately U-section as shown in Fig. 3. At the front end side 2a of this inside arm 2, there is a locking piece 6 having a pawl part 6a to be engaged with the tooth part 5a of the rack 5 of the outside arm 1. This locking piece 6 is rotatably mounted on the inside arm 2 as shown in Fig. 3, and is linked with the spring 9 disposed at the front end side 2a of the inside arm 2. At the front end side 2a of the inside arm 2, a second slot 7 and a rotatable stopping piece 4 are provided, and the stopping piece 4 is designed to project out of the first and second slots 3 and 7 disposed in contact with the abutting piece 8 of the outside arm 1. The stopping piece 4 has a stopping part 4a projecting out of the two slots 3 and 7, and a stopping part 4b designed to securely engage with and be stopped by the end part of the first slot 3. The stopping piece 4 is provided with a buffer mechanism 14 comprising a holding piece 10 of the stopping piece 4, a spring 13 for pulling this holding piece 10 in the contracting direction of the telescopic support arm, and a further slot 12 for slidably supporting the support shaft 11 of the stopping piece 4. The state of action of the telescopic support arm relating to the aforedescribed invention is described below. The telescopic support arm of the invention is used, for example as shown in Fig. 4, with one end of a telescopic support arm attached to one side of a door 15, and the other end of the telescopic support arm is attached to a support frame 16 on the same side of the door 15. A second support arm is similarly attached to the other side of the door 15. In this diagram, in the fully open position of the door 15, the stopping piece 4 of the inside arm is stopped in the front end side end portion of the first slot 3 of the outside arm 1. When extending the telescopic support arm from the contracted state, as indicated by virtual line in Fig. 5, the pawl part 6a of the locking piece 6 moves intermittently at small intervals along the tooth part 5a of the rack 5. That is, the pawl part 6a of the locking piece 6 is extended while being sequentially engaged with each tooth of the tooth part 5a of the rack 5. At this time, in the contrary direction, when a force in the contracting direction is applied to the telescopic support arm, the pawl part 6a of the locking piece 6 is engaged with the tooth part 5a of the rack 5 and arrested, thereby no longer contracting. By thus adjusting the engaging position, the telescopic support arm is adjusted to a desired length, and therefore the door 15 may be stopped at a specified position. When the telescopic support arm is extended, as shown by solid line in Fig. 6, the pawl part 6a of the locking piece 6 rides over the tooth part 5a of the rack 5, and the engagement of the pawl part 6a and tooth part 5a is cleared, and the locking piece 6 is returned to a position approximately vertical to the longitudinal direction by the spring 9. When the telescopic support arm is contracted from its extended state, as indicated by the dotted lines in Fig. 6, the back side of the pawl part 6a is moved along the tooth pat 5a of the rack 5, and hence the pawl part 6a of the locking piece 6 and the tooth part 5a of the rack 5 are not engaged with each other, so that the telescopic support arm is contracted smoothly. When the telescopic support arm is contracted, the pawl part 6a of the locking piece 6 rides over the tooth part 5a of the rack 5, thereby returning to the original state by the spring 9 as indicated by the solid line 5. Since the locking piece 6 returns to a position approximately vertical to the longitudinal direction in the position where it rides over the rack 5, the pawl part 6a and tooth part 5a are engaged with each other in the extending direction, and are not engaged securely in the contracting direction. Fig. 7 shows the position in which the telescopic support arm is extended, and the stopping piece 4 of the inside arm 2 is abutting against the abutting piece 8 of the outside arm 1. This is the position assumed immediately before the stopping piece 4 of the inside arm 2 projects out of the slots 3 and 7. Here, when the telescopic support arm is further extended, the stopping piece 4 of the inside arm 2 is rotated, by being pushed by the abutting piece 8 of the outside arm 1, thereby to slightly projecting out of the first slot 3 (see Fig. 8). At this time, when the telescopic support arm is contracted, the stopping piece 4 is moved away from the abutting piece 8, and the stopping part 4a of the stopping piece contacts with the front end side end portion of the first slot 3 of the outside arm 1. When pushed further in the contracting direction, the stopping piece 4 slightly rotates, and is securely stopped in the front end side end portion of the first slot 3 in the stopping piece 4b (see Fig. 9). From this position, when the telescopic support arm is extended, as shown in Fig. 10, the engagement of the stopping piece 4 of the inside arm 2 and the front end side end portion of the first slot 3 of the outside arm 1 is cleared, and the stopping piece 4 abuts against the abutting piece 8 again. At this time, since the stopping piece is turning, the abutting piece 8 contacts with the side free from the stopping part 4b of the stopping part 4. When extended further, the abutting piece 8 pushes to rotate the side free from the stopping part 4b of the stopping piece 4, while the stopping piece 4 stops its side free from the stopping part 4b at the rear end side portion of the slot 3 of the outside arm. Here, when the telescopic support arm is contracted, the other side is freed from the stopping part 4b of the stopping piece 4 and abuts against the front end side portion of the first slot 3. However, since this side has not stopping part 4b, the stopping piece 4 rotates and locates into the inside arm. At this time, the stopping piece 4 is rotated by 180 degrees from the original position. This position is evident in Fig. 11. As clear from the drawings above, the shaft 11 of the stopping piece 4 is disposed slidably in the slot 12, and is provided with a spring 13 for pulling the telescopic support arm in the contracting direction. Therefore, if the door 15 is opened forcefully, or alternatively a further force is applied in the extending direction to the telescopic support arm already in a fully extended state in ordinary use, the support arm is extended more by the length of the further slot 12 (see Fig. 12), and is returned to the ordinary maximum length by the spring 13, by the buffer action. In the state shown in Fig. 10, too, the telescopic support arm can be extended more by the length of the further slot 12, from the ordinary maximum length, by the buffer mechanism 14. Therefore, without giving direct damage to the members of the support arm, if the door 15 is distorted in its mounted state on the support frame 16 or there is a gap is mounting of the door 15 on the support frame 16, such distortion may be adjusted by the buffer mechanism 14 in the telescopic support arms at both sides of the door. In Fig. 14, penetration holes 17 are provided in both outside arm 1 and inside arm 2. By passing iron bars or the like into the penetration holes 17 of both outside and inside, the risk of sudden contraction of the telescopic support arm may be further reduced. In this embodiment, the penetration hole 17 is disposed at a specified position of the ordinary maximum length of the telescopic support arm, but it is not limitative, and it may be located at any position or at plural positions. It is also possible, needless to say, that the door can be locked by inserting a locking key or the like. A telescopic support arm of the invention according to the above construction brings about the following benefits. The specified arrangement of the slots, abutting piece and stopping piece, allows the support arm to be securely maintained at the position of an extended length,a nd by rotation of the stopping piece, the telescopic support arm once extended may be easily contracted. Furthermore, the construction of the buffer mechanism prevents, if the door is opened forcefully, or if the telescopic support arms are mounted with a distortion on both sides of the door, direct damage being induced on the abutting piece or stopping piece, so that the durability is excellent. The construction which permits the engagement of the tooth part of the rack and the pawl part of the locking piece, also permits the telescopic support arm to be set to a desired length. Therefore, it may be used in various doors, in a desired length, which is very convenient. By forming penetration holes, the support arm may have a higher safety, and it is also possible to secure by locking with a key.

Claims: A telescopic support arm comprising an outside arm (1) and an inside arm (2), the inside arm (2) being arranged to slide within the outside arm (1) between a contracted state and an extended state, the inside arm (2) having a stopping piece (4) for releasably securing the outside arm (1) at its extended state, characterised in that the outside arm (1) has a first slot (3), and an abutting piece (8) and the inside arm (2) has a second slot (7); in that the stopping piece (4) is rotatable by end portions of the first and second slots (3,7) and the abutting piece (8) and is disposed such that it engages with the end portions of the slots (3,7) in the extended state to resist movement of the arms; and in that there is provided a buffer mechanism which slidably supports the stopping piece (4) and which resiliently urges the stopping piece (4) in a contracting direction of the support arm. A telescopic support arm as claimed in claim 1, wherein the buffer mechanism (14) comprises a holding piece (10) of the stopping piece (4), a spring (13) for pulling the holding piece (10) in the contracting direction of the telescopic support arm, and a further slot (12) for slidably supporting a support shaft (11) of the stopping piece (4). A telescopic support arm as claimed in claim 1 or claim 2, wherein the outside arm (1) has a rack (5) possessing a tooth part (5a) disposed along the longitudinal direction, the inside arm (2) has a locking piece (6) possessing a pawl part (6a) for engagement with the tooth part (5a), the pawl part (6a) being arranged to move into engagement with the tooth part (5a) and thereby be arrested at a desired tooth of the tooth part (5a) to adjust the length of the telescopic support arm. A telescopic support arm as claimed in any preceding claim, wherein penetration holes (17) penetrating into both outside arm (1) and inside arm (2) are provided.

Inventors: YAGI KATUMI, YAGI, KATUMI
Applicants: YAGI & CO LTD, KABUSHIKI KAISHA YAGI
Application year: 1992
Main classification: E05C17
IPC codes: E05C17