Locking device

Abstract: A locking device is mounted on a bed of a truck or within an ambulance to lock or fasten goods on the bed or a stretcher within the ambulance. The locking device includes a frame (2), an operating handle (6) rotatably mounted on the frame (2), a link mechanism (L) connected to the operating handle (6) and having a recess (24a) defined therein, a hook (8) connected to the operating handle (6) via the link mechanism (L), and a locking pin (30) slidable relative to the operating handle (6). The hook (8) is locked by introducing the locking pin (30) into the recess (24a) and is unlocked by moving the locking pin (30) apart from the recess (24a).

Description: BACKGROUND OF THE INVENTION (Field of the Invention) The present invention relates to a locking device mounted on a bed of a truck or within an ambulance that carries sick or wounded people to lock or fasten goods on the bed or a stretcher within the ambulance. (Description of the Related Art) The stretcher is generally used to transfer a sick or wounded person to the inside of an ambulance. After having been transferred into the ambulance, the stretcher is usually placed on a vibration isolator or the like and is then locked or fastened thereto by a locking device. A ratchet mechanism is generally employed in the conventional locking devices for the stretchers. When the stretcher is locked, a hook is first raised and advanced, and is then locked by the ratchet mechanism. Conversely, when the stretcher is unlocked, a pawl is first released and the hook is then backed. Accordingly, the use of both hands is inevitably required, and not only is the operation troublesome, but also the locking and the unlocking can not be carried out rapidly. Furthermore, although various locking devices for locking goods on the bed of a truck have been proposed up to this time, many of them have only a small versatility or flexibility and, hence, cannot be used to lock the stretcher or other machines or apparatuses. In GB-A-2 082 515 there is disclosed an arrangement for locating and securing stretchers in ambulances. The securing or catch device of this known arrangement comprises a hook mounted rotatably around a vertical axis on a base structure. The hook is rotated by means of a lever between a locking position and a lock-released position. Another locking device is shown in US-A-4,671,713. This prior art device is intended for securely locking a wheelchair or like device in place during transportation thereof within a vehicle. The known locking device comprises a frame, an operating handle rotatably mounted on said frame, a link mechanism connected to said operating handle and a hook connected to said operating handle via said link mechanism with the hook being movable between a locking position and a lock-release position. In this known device the hook is movable in axial direction between its two positions under the influence of a handle and an eccentric cam arrangement. The prior art devices may serve their purposes but there are still improvements desirable. SUMMARY OF THE INVENTION The present invention has been developed to overcome the above-described disadvantages. It is accordingly an objective of the present invention to provide a reliable general-purpose locking device whereby locking and unlocking can be readily and rapidly performed using only one hand. In accomplishing the above and other objectives, the locking device according to the present invention includes a frame, an operating handle rotatably mounted on the frame, a link mechanism connected to the operating handle, a hook connected to the operating handle via the link mechanism and being movable between a locking position and a lock-released position, and an eccentric cam connected to the link mechanism, wherein a center of rotation of the hook at the locking position is moved below the center of rotation of the hook at the lock-released position by rotating the eccentric cam via the link mechanism, making it possible to positively perform the locking. Some preferred embodiments are disclosed in the dependent claims. In particular and advantageously, the locking device further includes a rocking shaft connected to the operating handle via the link mechanism, wherein the hook has an elongated opening defined therein in which the rocking shaft is loosely inserted. By this construction, the hook can be rapidly moved towards the locking position. The locking device further includes a locking pin slidable relative to the operating handle, wherein the link mechanism includes an arm having a recess defined therein, and wherein the hook is locked by introducing the locking pin into the recess and is unlocked by moving the locking pin apart from the recess, making it possible to perform locking and unlocking rapidly with simple operation. The locking device also includes an elastic member connected to the hook, wherein an elastic force of the elastic member acts on the hook in a first direction when the hook is at the locking position, while the elastic force of the elastic member acts on the hook in a second direction counter to the first direction when the hook is at the lock-released position. By so doing, not only can the locking and unlocking be performed rapidly, but the hook can also be positively held at the locking position or at the lock-released position. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objectives and features of the present invention will become more apparent from the following description of preferred embodiments thereof with reference to the accompanying drawings, throughout which like parts are designated by like reference numerals, and wherein: Fig. 1 is a perspective view of a vibration isolator for a stretcher to which a locking device is applied, particularly depicting the lock-released condition; Fig. 2 is a view similar to Fig. 1, but depicting the locked condition; Fig. 3 is a perspective view of a locking device under the lock-released condition; Fig. 4 is another perspective view of the locking device of Fig. 3; Fig. 5 is a perspective view of the locking device under the locked condition; Fig. 6 is another perspective view of the locking device of Fig. 5; Fig. 7 is a top plan view of the locking device of Fig. 5; Fig. 8 is a perspective view of a locking device according to the present invention under the lock-released condition; Fig. 9 is a partially cutaway perspective view of the locking device of Fig. 8; Fig. 10 is another partially cutaway perspective view of the locking device of Fig. 8; Fig. 11 is a perspective view of the locking device under the locked condition; Fig. 12 is a partially cutaway perspective view of the locking device of Fig. 11; Fig. 13 is a top plan view of the locking device of Fig. 11; Fig. 14 is a partially cutaway side view of the locking device for explanation of the operation thereof; and Fig. 15 is another partially cutaway side view of the locking device for explanation of the operation thereof. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Several locking devices according to the present invention are discussed hereinafter with reference to the drawings, taking the case where each locking device is mounted within an ambulance to lock a stretcher that carries a sick or wounded person. Figs. 1 and 2 depict a vibration isolator for the stretcher. This vibration isolator is used to place thereon the stretcher, on which a sick or wounded person is placed, to absorb vibration inputted to the stretcher, thereby lightening a burden applied to the sick or wounded person on the stretcher. As shown in Figs. 1 and 2, the vibration isolator includes a front locking device FL and a rear locking device RL. Under the unlocked condition shown in Fig. 1, the sick or wounded person together with the stretcher is placed on the vibration isolator, and the stretcher is then locked or fastened to the vibration isolator by the front locking device FL and the rear locking device RL, as shown in Fig. 2. The locking device is used, for example, as the rear locking device RL referred to above. Figs. 3 to 7 depict a locking device L which includes a frame 2 mounted on the vibration isolator, a pair of mounts 4, 4 disposed on respective sides of the frame 2, a generally U-shaped operating handle 6 rotatably mounted on the mounts 4, 4, and a hook 8 for locking the stretcher. The hook 8 is rotatably mounted, via a rotary shaft 12, on a bracket 10 slidably mounted on the frame 2, and has a rocking shaft 14 extending therethrough at an intermediate portion thereof. The bracket 10 is connected to one end of an adjusting bolt 16, the other end of which is fastened, by a nut 20, to a fastening member 18 threaded to the vibration isolator. The rocking shaft 14 are rotatably mounted at opposite ends thereof on ends of two arms 24, 24, the other ends of which are rotatably mounted on the operating handle 6 via respective pins 26, 26. Each of the arms 24, 24 has a recess 24a defined therein at an outer periphery thereof close to the associated pin 26 so that a locking pin (described later) may be received in the recess 24a during locking. A generally U-shaped lock releasing handle 28 is disposed inside the operating handle 6 and has two elongated openings (not shown) defined therein in which the pins 26, 26 are loosely inserted, respectively. The lock releasing handle 28 also has two locking pins 30, 30 secured thereto at locations close to the elongated openings so as to protrude laterally inwardly therefrom. The lock releasing handle 28 further has two elongated openings 32, 32 defined therein, in which pins 34, 34 are loosely inserted, respectively, to allow a sliding movement of the lock releasing handle 28 relative to the operating handle 6. A grip 28a of the lock releasing handle 28 is positioned adjacent to a grip 6a of the operating handle 6 and extends substantially parallel thereto. Opposite ends (lower ends) of the lock releasing handle 28 are connected to ends of coil springs 36, 36, the other ends of which are connected to pins 38, 38 secured to lower ends of the operating handle 6, respectively. The locking device L of the above-described construction operates as follows. When the locking of the stretcher is released, as shown in Fig. 1, the whole locking device L (RL) is positioned below the upper surface of the vibration isolator so as not to impede loading or unloading of the stretcher. Under the lock-released condition, the operating handle 6 is kept depressed together with the lock releasing handle 28, and the grip 28a of the lock releasing handle 28 is located at a position closest to the grip 6a of the operating handle 6, as shown in Figs. 3 and 4. At this moment, the hook 8 is held substantially horizontally by the link mechanism including the arms 24, 24 and the like, and the arms 24, 24 are held in contact at side portions thereof with the locking pins 30, 30, respectively. When the stretcher is locked after the stretcher together with a sick or wounded person has been led in the ambulance and placed on the vibration isolator, the grip 6a of the operating handle 6 is lifted, as shown in Figs. 5 to 7. At this moment, the lock leasing handle 28 is lifted together with the operating handle 6, and the arms 24, 24 are pushed by the associated locking pins 30, 30. As a result, the rocking shaft 14 extending through the hook 8 at an intermediate portion thereof is moved frontwards and, hence, the hook 8 is rotated about the rotary shaft 12 towards the locking position (erected position). When the hook 8 has reached the locking position, the locking pins 30, 30 are received in the recesses 24a, 24a formed in the arms 24, 24 at the ends thereof close to the pins 26, 26, respectively. At this moment, the lock releasing handle 28 is moved away from the grip 6a of the operating handle 6 by means of the biasing forces of the coil springs 36, 36, and is held at the position farthest from the grip 6a of the operating handle 6. At the locking position, the stretcher is locked or fastened by the hook 8, and the locking pins 30, 30 received in the associated recesses 24a, 24a of the arms 24, 24 prevent the locking from being released, even if external vibration is inputted. When the locking of the stretcher is released, the grip 6a of the operating handle 6 and the grip 28a of the lock releasing handle 28 are both grasped to bring the grip 28a near the grip 6a against the biasing forces of the coil springs 36, 36, thereby moving the locking pins 30, 30 apart from the associated recesses 24a, 24a of the arms 24, 24. Thereafter, when the operating handle 6 together with the lock releasing handle 28 is moved downwards, the hook 8 is rotated about the rotary shaft 12 via the link mechanism until it reaches the lock-released position shown in Figs. 3 and 4. Because the above-described locking device L is threaded to the vibration isolator by bolts extending through the elongated openings 2a, 2a in the frame 2 and is positioned by the fastening member 18 with the nut 20 and the adjusting bolt 16 threaded to the nut 20, the longitudinal position of the locking device L relative to the vibration isolator can be properly adjusted by rotating the adjusting bolt 16, making it possible to absorb variations in the vibration isolator and to positively lock the stretcher. It is to be noted that although in the above-described embodiment the lock releasing handle 28 has been described as being biased towards the locking position by the tension springs 36, 36, compression springs may be disposed, in place of the tension springs 36, 36, between the grip 6a of the operating handle 6 and the grip 28a of the lock releasing handle 28. Figs. 8 to 15 depict a locking device L according to the present invention, which includes a frame 102 mounted on the vibration isolator, a pair of generally parallel mounts 104, 104 secured to the frame 102 at a central portion thereof, a generally U-shaped operating handle 106 rotatably mounted on the mounts 104, 104 via a rotary shaft 105, and a hook 108 for locking the stretcher. The hook 108 is rotatably mounted, via an eccentric cam 112, on a bracket 110 threaded to the mounts 104, 104, and has an elongated opening 108a defined therein at an intermediate portion thereof. A rocking shaft 114 is loosely inserted in the elongated opening 108a, and is pivotally connected at opposite ends thereof to ends of first arms 116, 116. The other ends of the first arms 116, 116 together with ends of second arms 118, 118 are pivotally connected to the operating handle 106 by means of mounting bolts 119, 119, respectively. The other ends of the second arms 118, 118 are pivotally connected to ends of third arms 120, 120, the other ends of which are fixed to a connecting shaft 122 connected to the eccentric cam 112. Each of the first arms 116, 116 has a recess 116a defined therein at an outer periphery thereof close to the associated mounting bolt 119 so that a locking pin (described later) may be received in the recess 116a during locking. The hook 108 has a spring holder 124 secured thereto at a location close to the eccentric cam 112. A torsion spring 126 is connected at one end thereof to the spring holder 124 and at the other end thereof to the frame 102. The torsion spring 126 biases the hook 108 at the lock-released position in the direction of an arrow A and also biases the hook 108 at the locked position in the direction counter to the direction of the arrow A. A generally U-shaped lock releasing handle 132 is disposed inside the operating handle 106 and has two elongated openings (not shown) defined therein in which the mounting bolts 119, 119 are loosely inserted, respectively. The lock releasing handle 132 also has two locking pins 134, 134 secured thereto at locations close to the elongated openings so as to protrude laterally inwardly therefrom. The lock releasing handle 132 further has two elongated openings 132a, 132a defined therein, in which pins 136, 136 are loosely inserted, respectively, to allow a sliding movement of the lock releasing handle 132 relative to the operating handle 106. The first arms 116, 116 are appropriately spaced from the lock releasing handle 132 via spacers 128, 128 and from the hook 108 via spacers 130, 130. A grip 132b of the lock releasing handle 132 is positioned close to a grip 106a of the operating handle 106 and extends substantially parallel thereto. Opposite ends (lower ends) 132c, 132c of the lock releasing handle 132 are connected to ends of coil springs (not shown), the other ends of which are connected to pins 138, 138 secured to lower ends of the operating handle 106, respectively. Two adjusting bolts 140, 140 are mounted on the frame 102 on respective sides thereof, and two elongated openings 102a, 102a are formed in the frame 102 inside the adjusting bolts 140, 140 so as to extend substantially parallel thereto. A fastening bolt 142 loosely inserted in each of the elongated openings 102a, 102a is held by a mounting tab 44, to which associated one of the adjusting bolts 140, 140 is threaded. The operation of the locking device L of the above-described construction is discussed hereinafter. Under the lock-released condition, the operating handle 106 is kept depressed together with the lock releasing handle 132, and the grip 132a of the lock releasing handle 132 is located at a position closest to the grip 106a of the operating handle 106, as shown in Figs. 8 to 10. At this moment, the hook 108 is held substantially horizontally by the link mechanism including the first arms 116, 116 and the like, and the first arms 116, 116 are held in contact at side portions thereof with the locking pins 134, 134, respectively. Furthermore, the center of rotation of the eccentric cam 112 (the center of the connecting shaft 122 (a in Fig. 15)) is positioned below the center of rotation of the hook 108 (the center of a round hole in which the eccentric cam 112 is loosely inserted (b in Fig. 15)). Under the condition in which the rocking shaft 114 is located on the upper side of the elongated opening 108a in the hook 108, the hook 108 is biased in the direction of the arrow A by means of the biasing force of the torsion spring 126 employed as an elastic member. When the stretcher is locked after the stretcher together with a sick or wounded person has been led in the ambulance and placed on the vibration isolator, the grip 106a of the operating handle 106 is lifted, as shown in Fig. 14. At this moment, the lock leasing handle 132 is lifted together with the operating handle 106, and the rocking shaft 114 loosely inserted in the hook 108 at an intermediate portion thereof is rotated in the direction of an arrow B, thus rotating the hook 108 towards the locking position (erected position). Fig. 14 depicts the condition in which the hook 108 is located immediately before a change point. The elastic force of the torsion spring 126 acts on the center of rotation of the hook 108 at the change point. When the hook 108 is located on the side of the lock releasing position relative to the change point, the elastic force of the torsion spring 126 acts in the direction of the arrow A. On the other hand, when the hook 108 is located on the side of the locking position relative to the change point, the elastic force of the torsion spring 126 acts in the direction (direction of the arrow B) counter to the direction of the arrow A. Accordingly, upon further lifting of the operating handle 106, when the hook 108 has passed the change point, the elastic force of the torsion spring 126 acts in the direction of the arrow B, as described above. In addition, because the rocking shaft 114 is loosely inserted in the elongated opening 108a in the hook 108, the hook 108 is rapidly rotated in the direction of the arrow B and the distal end (locking portion) thereof is brought into contact with a portion of the stretcher. At this moment, the rocking shaft 114 is located on the side in the elongated opening 108a closer to the grip 106a. Under such condition, when the operating handle 106 is further lifted, the rocking shaft 114 is moved along the elongated opening 108a to the locking position shown in Fig. 15, and the locking pins 134, 134 are received in the recesses 116a, 116a of the first arms 116, 116 close to the mounting bolts 119, 119, respectively. At this moment, the lock releasing handle 132 is moved to and held at the position farthest from the grip 106a of the operating handle 106 by means of the biasing forces of the coil springs connected to the lower ends thereof. While the operating handle 106 is moved from the lock-released position (the condition shown in Figs. 8 to 10) to the locking position (the condition shown in Figs. 11 to 13 or Fig. 15) by way of the condition shown in Fig. 14, the eccentric cam 112 is rotated substantially half via the second and third arms 118, 118, 120, 120. Accordingly, the center of rotation of the eccentric cam 112, which has been positioned below the center of rotation of the hook 108 at the lock-released position, is positioned above the center of rotation of the hook 108 at the locking position and, during locking, the hook 108 is gradually moved downwards by the action of the eccentric cam 112 to positively lock a portion of the stretcher. At the same time, the locking pins 134, 134 are received in the recesses 116a, 116a of the first arms 116, 116, respectively, thus preventing the locking from being released by, for example, vibration inputted from the outside. When the locking of the stretcher is released, the grip 106a of the operating handle 106 and the grip 132a of the lock releasing handle 132 are both grasped to bring the grip 132a near the grip 106a against the biasing forces of the coil springs, thereby moving the locking pins 134, 134 apart from the associated recesses 116a, 116a of the first arms 116, 116. Thereafter, when the operating handle 106 together with the lock releasing handle 132 is moved downwards, the hook 108 is rotated about the eccentric cam 112 via the link mechanism until it reaches the lock-released position. Because the above-described locking device L is threaded to the vibration isolator by the fastening bolts 142, 142 loosely inserted in the elongated openings 102a, 102a in the frame 102, the longitudinal position of the locking device L relative to the vibration isolator can be properly adjusted by rotating the adjusting bolts 140, 140, making it possible to absorb variations in the vibration isolator and to positively lock the stretcher.

Claims: A locking device (L) comprising: a frame (102); an operating handle (106) rotatably mounted on said frame (102); a link mechanism connected to said operating handle (106); and a hook (108) connected to said operating handle (106) via said link mechanism, said hook (108) being operable to move between a locking position and a lock-released position, characterized by : said hook (108) having a center of rotation (b); and by an eccentric cam (112) connected to said link mechanism and operable to move said center of rotation of said hook (108) such that said center of rotation of said hook (108) at the locking position is below said center of rotation of said hook (108) at the lock-released position by rotation of said eccentric cam (112) via said link mechanism. The locking device (L) according to claim 1, further comprising an elastic member (126) connected to said hook (108), wherein an elastic force of said elastic member (126) acts on said hook (108) in a first direction when said hook (108) is at the locking position, while the elastic force of said elastic member (126) acts on said hook (108) in a second direction counter to the first direction when said hook (108) is at the lock-released position. The locking device (L) according to claim 1, further comprising a rocking shaft (114) connected to said operating handle (106) via said link mechanism, wherein said hook (108) has an elongated opening (108a) defined therein in which said rocking shaft (114) is loosely inserted. The locking device (L) according to claim 3, further comprising a locking pin (134) slidable relative to said operating handle (106), wherein said link mechanism comprises an arm (116) having a recess (116a) defined therein, and wherein said hook (108) is locked by introducing said locking pin (134) into said recess (116a) and is unlocked by moving said locking pin (134) apart from said recess (116a). The locking device (L) according to claim 4, further comprising a lock releasing handle (132) slidable relative to said operating handle (106), wherein said locking pin (134) is secured to said lock releasing handle (132). The locking device (L) according to claim 1, further comprising: a lock releasing handle (132) slidably connected to said operating handle (106); and an elastic member (126) connected to said hook (108) for biasing said hook (108). The locking device (L) according to claim 6, wherein said lock releasing handle (132) and said operating handle (106) are arranged such that said lock releasing handle (132) is operable to slide along a longitudinal direction of said operating handle (106). The locking device (L) according to claim 6, wherein said locking pin (134) is secured to said lock releasing handle (132). The locking device (L) according to claim 1, further comprising a rocking shaft (114) connecting said hook (108) and said link mechanism. The locking device (L) according to claim 9, wherein said link mechanism comprises: a first arm (116) having a first end connected to said rocking shaft (114) and having a second end rotatably connected to said operating handle (106); a second arm (118) having a first end rotatably connected to said operating handle (106) and having a second end; a third arm (120) having a first end rotatably connected to said second end of said second arm (118) and having a second end connected to said eccentric cam (112).

Inventors: SAKAMOTO YUTAKA, SAKAMOTO, YUTAKA, Sakamoto, Yutaka, c/o Delta Tooling Co., Ltd.
Applicants: DELTA TOOLING CO LTD, DELTA TOOLING CO., LTD.
Application year: 2000
Main classification: A61G1
IPC codes: A61G1, A61G3